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DEC-CP-GAYB-D

December 1969

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Document:	GLC-8 Chromatogrphers Guide
Order Number:	DEC-CP-GAYB-D
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Pages:	62
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GLC-8
A COMPUTERIZED SYSTEM
AUTOMATING GAS-LIQUID

CHROMATOGRAPHY

For additional copies of this manual, order No.

DEC-CP-GAYB-D from the Program

Libary, Digital Equipment Corporation, Maynard, hAass. 01754

DIGITAL EQUIPMENT

CORPORATION n MAYNARD

Price $2. 00

MASSACHUSETTS

1st Edition March 1969
2nd Edition (Rev) June 1969

Your attention is invited to the last two pages of this
manual. The Reader's Comments page, when filled in
and returned, is beneficial to both you and DEC. All
comments received are considered when documenting
subsequent manuals, and when assistance is required, a
knowledgeable DEC representative will contact you.
The Software Information page offers you a means of
keeping up-to-date with DEC's software.

Instruction times, operating speeds and the like are in-

cluded in this manual for reference only; they are not to
be token as specifications.

Documents Referenced (available from DEC's Program Library):

C-18
8K FORTRAN Programmer's Reference Manual, DEC-08-KFXB-D

Introduction To Programming,

P DP -8/1 System User's Guide,

DEC-08-NGCB-D

The following are registered trademarks of Digital
Equipment Corporation, Maynard, Massachusetts:

DEC

PDP

FLIP CHIP

FOCAL
COMPUTER LAB

DIGITAL

CONTENTS
Page

CHAPTER

INTRODUCTION
1.1

Monitor System

1-1

An Overview

1-2

System Configuration

-5

1.3.1

Local Operator's Console

1-6

1.3.2

Hardware Options

1-8

System Software

-8

System Initialization

1-8

Using The Teletype Console

1-9

1.7

Modes Of Operation

1-10

1.8

Error Messages

1-10

1.5
1

CHAPTER 2

MONITOR COMMANDS
2.1

ASSIGN Command

2-2

2.2

ENTER Command (Building a Method)

2-3

2.3

ANALYZE Command

2-12

2.4

CALIBRATE Command

2-14

2.5

MODIFY Command

2-14

2.6

DUMP Command

2-15

2.7

DELETE Command

2-16

CHAPTER 3
USING GLC-8
3.1

ASSIGN Chromatogroph And Teletype

3-1

3.2

ENTER Method

3-1

3.3

DUMP Method

3-2

3.4

ANALYZE With Method

3-2

3.5

ENTER Method 23

3-3

3.6

CALIBRATE Method 23

3-6

3.7

DUMP Method 23

3-6

3.8

ANALYZE With Method 23

3-8

CONTENTS (Cont)
Page

APPENDIX A

LOADING AND STARTING PROCEDURES
APPENDIX B

SUMMARY OF COMMANDS, QUESTIONS, AND RESPONSES
APPENDIX C
ERROR MESSAGES
APPENDIX D
ANALYSIS SEQUENCE
INDEX

ILLUSTRATIONS

A GLC-8 Method (top) and Analysis Report (bottom)
G LC-8 System Configuration

Local Operator's Console

1-7

Method

3-2

Chromatogram Recording

3-4

Area Normalization Analysis Report

3-5

Method 23 Before Calibration

3-6

Calibration Report of Method 23

3-7

Method 23 After Calibration

3-7

Actual Analysis Report Using Method 23

3-8

System Operation

3-9

1-3

-6

TABLES
1

2-7

Functions

PREFACE

GLC-8 is dec's computerizecl system for automating the gas-liquid chromatography laboratory.

This

manual covers the use of GLC-8 from the chromatographer's viewpoint (the scientist, engineer, or
laboratory technician), describing the system and how to use it efficiently.

GLC-8 is compatible with virtually any gas-liquid chromatograph or detector (thermal-conductivity,
flame ionization, electron capture, etc.), therefore, the manual assumes that you are thoroughly
familiar with your chromatograph or detector.

Chapter 1 offers a "bird's eye" view of GLC-8, the system operation and configuration.

Chapter 2 is

devoted to explaining how you communicate with the system and what GLC-8 does for you when you
do.

Chapter 3 describes an actual analysis using GLC-8 with a Perkin-Elmer 900 Chromatograph, The

appendices contain summarized operating information.

The "heart" of GLC-8 is a set of programs called Monitor, which interact conversationally with the
chromatographer

The PDP-8/1 System User's Guide (DEC-08-NGCB-D), furnished with the system, is frequently
referenced for console, loading and operating instructions.

Documents referenced:

PDP-8/1 System User's Guide, DEC-08-NGCB-D

GLC-8 Maintenance Manual, DEC-08-HGAA-D

CHAPTER

INTRODUCTION

The science of gas-liquid chromal-ography has come a long way since it was discovered in
1

952

GLC-8 is another step forward

GLC-8 (Gas-Liquid Chromatography for the PDP-8/I) is a computerized system for automating
the gas-liquid chromatography laboratory.

With GLC-8, the tedious task of measuring strip-chart

recordings is eliminated, analysis becomes exceptionally reproducible, and the result of each analysis
is available

in a typed report within seconds rather than hours.

The GLC-8 system performs on-line analysis calculations on as many as 20 chromatographs*
simultaneously.

A simple dialogue between the chromatographer (using the Teletype console) and the

GLC-8 Monitor enables him to specify the manner in which the analysis is to be performed, to request
a method, run an analysis or calibration, and to receive a typed report of the analysis.

GLC-8 is designed primarily for use with gas-liquid chromatographs; however, it may be
used with other analytical instruments (e.g. , amino-acid analysers) which use the same method of
analysis as the chromatograph

The system will operate on systems utilizing thermal conductivity,

flame Ionization, and electron capture detectors, and will allow parallel operation of a strip-chart
recorder and attenuation switching.

GLC-8 is primarily a special-purpose system, dedicated to chromatographic analyses.
However, when the system isn't being used to control analyses it is available as a genera -purpose
I

computer for use with such programs as FOCAL, BASIC-8, FORTRAN, PAL III, MACRO-8, or the
Disk Monitor System.

1.1

MONITOR SYSTEM
The heart of the GLC-8 system is appropriately named Monitor since it monitors and controls
Monitor is composed of many computer prpgrams which reside in core

every phase of the analysis.

memory (PDP-8/l computer)

During each analysis. Monitor performs the following functions.

Samples each channel at the rate specified In the analysis method.

Selectively attenuates the effect of channel noise with digital signal filtering, as

specified in the method.

Detects peaks and shoulders.

* This number may vary with certain configurations.

1-1

Integrates the area under the peaks and shoulders.

Condenses all this information into a file and stores it on the disk.

When the specified time of the anal/sis run is reached or when the analysis is terminated.
Monitor takes the information accumulated during the analysis and
a.

Performs sophisticated baseline corrections.

Reallocates the area of fused peaks to give an accurate area measurement for each peak.

c .

Adjusts retention times relative to the predefined reference peak in the method.

Identifies and names each component or peak.

Applies an internal standard, if requested in the method.

Applies response factors.

Calculates component concentrations.

Types out a complete, accurate report of the analysis.

Monitor analyzes and interprets the chromatographic data according to the method specified.
In essence. Monitor automatically performs everything except sample injection;

there is no manual

data reduction or analysis after the method of analysis has been specified.

1.2

AN OVERVIEW
The brief description of an analysis that follows reveals the features and usefulness and

flexibility of GLC-8.

Questions arising will be answered as you read on.

To start an on-line chromatographic analysis, you have only to type

ANALYZE, 18, 7,

to inform Monitor that you wish to initiate an analysis on chromatograph number 7 using method

number 18.

(See Figure

Monitor makes the following checks:

method 18 written for chromatograph 7?

b.
Can the sample rate of the analysis be fitted into the schedule?
data points per second* can be processed at any one point in time.)

(No more than 240

c .

there sufficient disk storage to hold the collected chromatographic data?

chromatograph 7 available for this analysis (i .e

Thl s is true for a

60-cycle system

not busy running another analysis) ?

For a 50-cycle system, the maximum rate is 200 samples/second

1-2

ENTER, 18 »0,

W:>
TW,
TM,
TM,
TM,
TM,
TM,

RRT, TBEG, TEND
CODE, VAL
CODE, VAL
CODE, VAL
CODE, VAL
CODE, VAL
CODE, VAL
CODE, VAL
NAME, TOL, RF, CWT
NAME, TOL, RF, CWT
NAME, TOL, RF, CWT
NAME, TOL, RF, CWT
NAME, TOL, RF, CWT
NAME, TOL, RF, CWT
NAME, TOL, RF, CWT
NAME, TOL, RF, CWT

---------------------

ID,

RC YCL

ANALYZE, 18, 7,
DEMO,0 ,

INST, PK CT
IJNK, FF, SMPR
RIYP, AF
IS

TM/SCALE

RPKT,
F TM,
F TK,
F TM,
F TM,
F TM,
F TM,
F TM,
TMj.

20,

100,

224,
224,

,
:

1000,

200,

>
*

4,
5,
6,
9,
7,

500,
510,
15,

27,
57,
103,
146,
224,
320,
41 1,

250,

1,
1,
f

AIR
CLOHAN,
PENTLl
CYCHOL,
PHENOL,
CYCHON,
DICYCL,
DIC-EH,

5,
5,
5,

blZ'i,,

192,
163,

5,
5,
5,
5,

9120,
10530,
6127,
9999,
5832,
7185,

RF FACT

COMP

3963,
190,

4192,
47 1,
829,

NORM

10000:

ANALYSIS
DATE

INST

TIME

METHOD

1235

NORM

DEMO

10000

PEAK AREA* TYPE

COMPONENT

RRT

TIME

AIR

.071

9033

CLOHAN

124

13464

6785

PENTLl

.253

8478

9120

CYCHOL

.462

104

178102

10530

PHENOL

.653

147

14595

6127

CYCHON

•

999

225

198655

TOL

.000%

18%

.929%

17%

.632%

39.603%

10%

.888%

9999

41 .946% +

DICYCL

.426

321

38148

5832

4.69 7%

DIC-EH

.831

412

54715

7185

8.301%

16%

Figure

A GLC-8 Method (top) and Analysis Report (bottom)

*An exclamation mark (I) raises the typed number to the power of 3.
typed number to the power of 6.

1-3

A quote mark (") raises the

If Monitor finds a

"no" answer to any of these questions, it will type a three-character error-message

code indicating which condition cannot be met.

Monitor would then ignore your request and wait

for you to issue another.
If the analysis

can be handled. Monitor will ask you to name the analysis and state whether

you want to repeat the method of analysis using other samples.

If the analysis is

to use the internal

standard calculation technique. Monitor asks you to enter the sample and internal standard weights.
After you have answered these questions, the READY light on the local operator's console

(LOG) associated with chromatograph 7 is turned on. The system is now ready for you to infect the
sample.

Immediately after sample injection, you should depress the START pushbutton on the LOG;

the SAMPIing light will illuminate.
If you wish to cancel

The system is now running the analysis.

the analysis, depress the CLEAR pushbutton on the LOG.

abort the run and Monitor will return to command mode.
analysis, depress the STOP pushbutton on the LOG.

If you wish

This will

to prematurely terminate the

This will generate an analysis report based on the

accumulated data.
Unless interrupted, the run will complete itself at the time specified by the method being

used.

Upon completion of the analysis the GOMPute light on the LOG turns on and Monitor performs

the fol lowing on the accumulated chromatographic data

Baseline correction

Resolution of overlapping peaks

Galculation of adjusted and relative retention time

Identification of peaks

Gomputation of internal standard

Adjustment by relative response factors

Calculates component concentrations

Types a concise, accurate report of the analysis

The typed report lists all identified components, unknown peaks, and not-found components
in the chronological order in which they eluted (or should have eluted, in the case of not-found

components).

The following data is typed for each peak (see Figure 1)

Name or UN Known

Relative retention time

Retention time

Peak area

Peak type

1-4

Response factor

Component percent

Retention tolerance

Relative retention time is based upon a stated relative retention time of the

reference peak.

reference peak is a peak on the chromatogram and is used to scale the time frame

The

(window) of the

chromatogram when the method is built.
Peak type demonstrates the basic nature of the peak by denoting how it started and how it

ended.

and

For example, in the preceding analysis report, the first three peaks were

identified as BB,

BV,

W, in the peak type column of the report; the following occurred:
a

The first peak, BB, started at a baseline and terminated at a baseline.

The second peak, BV, started at a baseline and ended in a valley.

The third peak,

W, started in fusion with the valley and ended on

its

reverse slope

by fusing with another valley.
Retention time tolerance, the rightmost column in the report, is a diagnostic feature
indicates whether a peak identified with a component had a retention time before or

ponent's expected retention time as determined by the selected method.
of 100%,

If a

which

after the com-

component has a tolerance

of
was sitting on the upper bound of its tolerance. This figure constantly reflects the state

column aging.

1.3

SYSTEM CONFIGURATION
The major hardware components of the basic GLC-8 system for simultaneous

acquisition and

analysis of data are listed below.

One PDP-8/l computer with at least 8K words of core memory and an EAE unit (KES/l)

for fast arithmetic operations

One 32K disk (DF32)

Type AF06-A interface: 64 channel multiplexer, 1 x 10 dynamic range analog-toup to 64 LOCs
digital converter, 4x line frequency clock (240 cps*), and control for
c.

At least one ASR33 Teletype (to a total of nine)

Figure 2 illustrates the GLC-8 system configuration.
of the system see the GLC-8 Maintenance Manual,

For additional technical specifications

DEC-08-HGAA-D.

*200 cps for 50-cycle systems

1-5

FROM LOC

'RELAYS OPTIONAL

H301 LOG

CaNTROL<
LOGIC

L^
1st

LOCAL

zu r

OPERATOR'S

CONSOLE

INTERFACE

DIFFERENTIAL
ISOLATION
AMPLIFIER

GAS
CHROMATO-

GRAPH

U>-\

2 HZ

FILTER

2nd

LOCAL

32K
WORD

OPERATOR'S

PROGRAMMABLE

CONSOLE

DISK

NINE GAIN

RANGE

64
CHANNEL

GAS
CHROMATOGRAPH

tit*—tP^

IrltIrI

AMPLIFIER

(OPTIONAL)

MULTIPLEXER

a CONTROL

12 BIT

PDP-8/I

ANALOG -TO-

8K
EAE

DIGITAL

CONVERTER

PT08B(C)

TELETYPE

CLOCK

4x LINE
FREQUENCY

nth

LOCAL

INTERFACE
CONTROL

OPERATOR'S

CONSOLE
L.O. C.

GAS
CHROMATO-

GRAPH

CONTROL

2HH
filter

J
TTY
(OPTIONAL)

Figure 2 GLC-8 System Configuration

1 .3 . 1

Local Operator's Console

A local operator's console (LOC) is associated with and often connected to each chromatograph.

A LOC is shown in Figure 3.
Pushbuttons are used to control the operation of the computer.

The purpose of each is as

follows.

CLEAR

Depress to cancel the anal/sis and clear the

channel .

This button can be used at any

time.

START

STOP

Depress to start the analysis.
Depress to terminate the analysis and generate the
analysis report.

1-6

The indicator lights reveal the status of the analysis, as explained below.

READY

Lights when the system is ready for sample injection.

SAMPLE

Lights when START is depressed to indicate that the

analysis is in process.

COMPute

Lights when the report is being generated and typed.

Figure 3

Local Operator's Console

1-7

1.3.2

Hardware Options
The most commonly added options to a GLC-8 system are Teletypes.

The system will support

up to nine Teletypes operating independently and simultaneously. When additional Teletypes (after the
third) with their PT08s are added, the number of chromatographs which may be operated simultaneously
is

reduced on a one-for-one basis.

1.4

SYSTEM SOFTWARE
The GLC-8 system operates under control of its Monitor.

Monitor is composed of various

programs which control the operation of the analog-to-digital (A/D) converter, multiplexer, range
amplifier, local operator's console, and interprets both Teletype input and output.

Monitor's functions

can be divided into two mafor sections:
a.
Foreground programs process the chromatographic data, forming and integrating peaks,
and storing on the disk parameters characterizing individual peaks, which include
(1)

Sampling and digital signal filtering

(2)

Threshold logic peak detection

(3)

Integration of area under peaks and shoulders

(4)

Peak and shoulder detection

(5)

Storage of peak parameters on disk

b.
Background programs are called into action by Monitor when they are needed.
are two groups of background programs: conversation and report generation

There

Conversation programs allow entering, changing, deleting, and reporting analysis
(1)
methods. Monitor's conversation programs are those which accept and respond to your
typed input. They also maintain a library of up to 100 different analysis methods and
facilitate the updating and control of stored methods (i.e., printout, entry of new
analysis methods, deletion of stored methods, changing of methods, and audit trial

dumps)
Report generator, at the end of an analysis, processes the stored chromatographic
(2)
data and produces the analysis report on the Teletype.

1.5

SYSTEM INITIALIZATION
The GLC-8 Monitor is loaded into core and activated as explained in Appendix A.

When

the system is started Monitor assumes control and automatically types

V10:
(VIO:

is the

MONTH,

DAY,

YEAR,

HOUR,

MINUTE

version number of the system program) and waits for you to type the above information in

the following format.

1-8

AA,BB,CC,DD,EE,

AA is the number of the month (1-12)

where

BB is the number of the day (1-31)

CC is the number of the year (last two digits only)
DD is the hour (in military time, i.e., 24-hour clock)
EE is the number of minutes after the hour (1-59)
For example,

2,18,69,14,30,
which is February 18, 1969 at 2:30 p.m.

Monitor examines your input for correct format, and if an

error is detected, it ignores that information and repeats the question and waits for you to

try again.

When the information has been entered correctly. Monitor sets its "calendar" and "clock'
and heads each typed report with the date and time the analysis report was started (see Figure

1).

Incidently, Monitor's calendar even recognizes leap years.

1.6

USING THE TELETYPE CONSOLE
Communication between you and Monitor is through the Teletype console.

Each Teletype

operates independently on a time-sharing basis, giving each user the feeling of having the whole

system to himself.

Monitor divides the Teletype paper into two sections: the left half is for Monitor's output

and the right half is for your input, except when Monitor is typing an analysis report.

Figure

reveals the division line.
Initially, Monitor spaces over toward the center of the paper and waits for you to give it

a command (referred to as being in command mode)

You need only specify the task and indicate

how you want it done and Monitor will either go and perform the task or it will ask a series of
questions to determine precisely how you want the task performed.

When Monitor spaces over to your side of the paper and pauses, it is in command mode and
is waiting

for you to type one of its seven commands:

ASSIGN

(allows a chromatograph to be assigned to a specific Teletype)

ENTER
CALIBRATE

(initializes a calibration)

(allows the on-line entry of a method)

ANALYZE
MODIFY
DUMP

(initializes an analysis)

DELETE

(allows the deletion of specific method(s))

(allows modification of a method)
(allows the print and/or punch of specific method (s))

Each command is discussed in detail in Chapter 2 and is summarized in Appendix B.

1-9

1.7

MODES OF OPERATION
When the system Is operating. Monitor is in any one of seven modes of operation

Monitor is waiting for you to issue a command, it is in command mode.
issued correctly,

it is

in the mode of the

When

After a command has been

command. For example, when Monitor is in command mode

and you type

MODIFY, 23 ,3,:
Monitor transfers to its modify mode.

Monitor is always in the mode of the operation it is performing

except, of course, when it is In command mode.

modes as there are Teletypes

1.8

~ each Teletype

Monitor may be operating simultaneously in as many
independent and can be operating in a different mode.

ERROR MESSAGES
Whenever you terminate a line, using the last comma when initializing or the colon for all

other lines. Monitor checks your input for proper format.

If Monitor detects an

improperly formatted

response, it either types a three-character error message, ignores your input, and returns

mode or it repeats the question.

All error messages are explained in Appendix C.

1-10

to command

CHAPTER 2

MONITOR COMMANDS
When the GLC-8 Monitor is loaded into core, activated, and initialized (see Appendix A),
Monitor spaces toward the center of the Teletype paper where you are to enter a Monitor command,

which tells Monitor what you want done (see Figure 1).

For example, if you want to build and enter a

new method , you type
ENTER,mn,:
where ENTER is the Monitor command, mn is the number to be assigned to the method you plan to build,
and the colon terminates the line, returning control to Monitor.

When entering a method using the paper tape reader, the ENTER command should always
include a second parameter:

ENTER,mn,l,:
where the second parameter (number 1) causes Monitor to suppress its questions.
pressed when entering a method from the keyboard.

suppressed, an error message is typed out.

If an error is made

Questions can be sup-

when entering with the questions

Typing a colon directly after the error message causes

Monitor to type *P0 and then type the question (the response to which contained the error) and subse^

quent questions are typed during the entering of the particular method.

A Monitor command and the parameters to a command are terminated by commas.
NOTE
Monitor always interprets no reply as a

reply.

There-

fore, since each parameter is terminated by a comma, the

following are identical.

—0,75,0,:
-,75,,:
This convention applies throughout GLC-8.

The seven Monitor commands are shown below with the required parameters (entered as decimal integers) and a concise explanation of each

In the following

examples, the parameters are coded

as follows.

Method number (decimal integer, 0-99)

Questions:

Chromatograph number (decimal integer, 1-64)

Teletype number (decimal integer, 1-9)

ENTER,mn,q:

Used to build and enter a new method into the method library
maintained in disk storage.

= type question; 1 = do not type questions*

typing a second colon restores questions.
suppressed only when entering methods using the paper tape reader.
*If this is accidently entered,

2-1

We suggest that questions be

ASSIGN, en, tn,:

Assigns subsequent reports of chromatograph en to be typed on

Teletype tn.

ANALYZE,mn,en,:

Method mn will be used on the analysis of chromatograph en.

MODIFY, mn,:

Method mn is transferred from disk into eore where Monitor types
a line-by-line copy of that method, pausing after typing each
line to permit you to modify

by entering new parameters.

CALIBRATE, mn, en,:

Used to perform a calibration analysis on method mn using chromatograph en.

DELETE, mn,mn,:

Deletes methods mn through mn from the method library; If only
one method is to be deleted, the second parameter is not specified.

A copy of methods mn through mn are typed on the Teletype; if
only one method is desired, the second parameter is not specified.

DUMP,mn,mn,:

Each of the above commands ore explained in detail within this chapter.

Monitor commands are sum-

marized in Appendix B.

Monitor commands may be abbreviated to the first four letters of the command because Monitor reads only the first four letters of its commands.

For example,

ENTER,

may be abbreviated to ENTE,

CALIBRATE,

may be abbreviated to CALI,

ANALYZE,

may be abbreviated to ANAL,

Thus, a Monitor command may be misspelled and still be interpreted correctly so long as the first four
letters are spelled correctly.

In other words,

ANALYSIS and ANALYSES are interpreted as ANALYZE

by Monitor,.

2.1

ASSIGN COMMAND
The ASSIGN command is used to establish Teletype/chromatograph assignments and reassign-

ments.

When a Teletype is assigned to a chromatograph the analysis reports from that chromatograph

will be typed on the assigned Teletype.

To assign or reassign chromatograph 12 to Teletype 2, you have only to type

ASSIGN, 12,2,:
Monitor accomplishes the assignment and returns to command mode.

The assignment will remain valid

until reassigned using another ASSIGN command.

A Teletype can be assigned to any number of chromatographs
be assigned to only one Teletype at any one time.

If any

However, a chromatograph can

attempt is made to assign a chromatograph to

more than one Teletype, Monitor will recognize the last Teletype number entered and ignore the others.
Unless otherwise assigned, all chromatographs are assigned to Teletype

2-2

Reassignment can be made at any time, even when the chromatograph is busy.

If, in

the

example above, chromatograph 12 had been running an analysis when the reassignment was made, the
reassignment would be accomplished and the analysis report of the analysis running on chromatograph 12

would be typed out on Teletype 2.

ENTER COMMAND (BUILDING A METHOD)

2.2

To perform an analysis you need a method.

The method has two primary functions:

To define the technique by which the sample is to be analyzed.

To specify the expected components in the sample.

Methods are built during a question and answer session between Monitor (asking questions)
and you (answering).

The method building session begins after you type the command ENTER and the

number to be assigned to the method. The ENTER command is typed when Monitor is in command mode.
To build method number 13, you may type

ENTER, 13,:
If a

method numbered 13 is already on the disk. Monitor types the error message *U2 imme-

diately after the colon.

(See Appendix C for a list of all error messages and their explanations.)

However, assuming the command is correct and a method number 13 is not already on the
disk. Monitor would return to its side of the paper and ask the following question.

INST, PK CT
and wait for you to specify the chromatograph (INST, for instrument) number (1-64) to which this method
will be assigned,

(1-200).

and the maximum number of peaks (PK CT, for peak count) expected in the analysis

Each method is assigned to a specific chromatograph, except for method

which can be used

with any chromatograph (see Chapter 3)

The peak count number is needed as a safeguard against getting page-after-page of "unknowns"
if noise

spikes start registering as peaks.

Therefore, a realistic peak count number should be used.

Monitor types two minus signs to invite you to type in parameters to its question; these two
minus signs can be considered as a question mark (?).
If the

method is to be assigned to chromatograph number 3 with a peak count of 25, you

should type

INST, PKCT
If you

—3,25,:

notice a typing error before typing the colon, for example,

INST, PK CT

—13,35,

2-3

you should type two minus signs and then type the correct parameters. When Monitor types two minus
signs it is inviting you to enter some data with which to control the analysis.

However, when you type

two minus signs (the first minus sign prints, the second minus sign is read by Monitor but not printed on
the Teletype) you are telling Monitor to ignore everything enclosed by the double minus signs.

For

example,

INST,PKCT

—13,35,-3,25,:

and Monitor ignores 13,35, and accepts 3,25,:.

When you type a colon Monitor checks your input for validity before it asks the next question.

When Monitor does not detect on error it proceeds to the question shown below.

UNK,FF,SMPR
By UNK, Monitor wants to know how to treat unknowns.

You should type 0, 1 , or 2 in re-

sponse to this question, where

= Apply a response factor of
1

= Apply a response factor of 1

2 = Apply the response factor of the last identified peak.

Since the weight percents printed in the report are calculated using the response factors of each of the

components and their peak areas, UNK =0 allows you to get a printout where unknowns are not included
in the percentages.

UNK =

or 2 both include these components in the weight percentages.

UNK = 2 is helpful

when the general response factor changes during the run as a more or less linear function of time.
By FF (filter factor). Monitor wants you to specify how much smoothing is to be done to the

chromatograph signal before testing for peak start, end, shoulders, etc.

A number from

to 7 should

be your reply, determined using the following algorithm:
SS new = (new unsmoothed signal) + (1-2

)

x (SS old)

where SS is smoothed signal and FF is filter factor (0-7).
Filter factor aids in the detection of peaks.

satisfactory.

For most analyses, a filter factor of

or 1

When very small peaks are expected, the filter factor should be raised either by raising

the filter factor value when building the method or by the use of function code 11 , which allows one to

vary the filter factor during the analysis.
tivity to small peaks.

This improves to signal to noise ratio and improves the sensi-

Filter factors of from 4 to 7 will aid the detection of slow small peaks, but

should not be used unless these are expected in the run.

A high filter factor should not be used with

sharp quick peaks.

By SMPR, Monitor wants to know the sampling rate.

The sample rate should be only as

much as is needed to achieve the desired standard of repeatibility and to detect small peaks. Usually
3.75 or 7.5 data points per second is more than ample. Therefore, to determine the correct sampling

2-4

determine the length of the
rate for a given sample and chromatograph, use the strip-chart recording to
fastest peak or shoulder of interest and divide that length into 20,

and then select the next highest sampl-

ing rate from the following table.

Sample Rate
(Samples/Second)

SMPR

50 cps
03.125
06.25
12.5
25.0
50.0

60cps
03 .75
07.5
15.0

2
3

30.0
60.0

4
5

For purposes of this discussion, we will assume your response to UNK,

FF,SMPR is as shown

below.

~1,1,2,:

UNK,FF,SMPR
Next, Monitor types

RTYP,AF
where RTYP means report type and AF means area factor. Your reply to RTYP must be one of the
following.

= Area normalization type calculation
= Internal standard type calculation
2 = External standard type calculation
1

With RTYP = 0, an internal standard peak is specified in the normalization type calculation to

one peak about which the response factor of all other peaks are scaled in calibration
factor of this peak is always

The response

.0.

Your reply to AF can be any decimal integer from

to 100.

Area factor is a control of the

Area factors of 100% mean that

degree to which GLC-8's area reallocation is used (see Appendix D) .

the full area reallocation algorithm is used; 50% means that only 50% of the area

reallocation is used;

reduces the area reallocation to the equivalent of dropping the perpendicular technique.
factor is increased (from

select

As the

to 100), the percentage of the area reallocation from the smallest peak to the

next largest adjacent peak increases.
If Monitor detects an

input error, the question is repeated

your reply to RTYP, AF, it types the next question

When Monitor is satisfied with

IS TM/SCALE

question.
Your response to this question depends on the type of calculation specified in the preceding
If the report type specified is

normalization (0) or internal standard (1), your response should be the

retention time of some peak in the chromatogram .

If all

peaks are unknowns, a dummy internal standard

peak should be set to one second, at which time, of course, no peaks wi II be seen

2-5

The time of the

internal standard peak must be identical to one of the components listed in
the compound table.

report type specified

external standard (2), the scale factor is used to scale down peak areas.

scale factor is an exponent (10

-SF
),

If the

The

and a value of 0-7 is normally sufficent.

Monitor's next question is:

RPKT, RRT, TBEG, TEND

where RPKT and RRT, respectively, represent adjusted and relative retention times

of the reference peak,

and TBEG and TEND represent the beginning and ending of the eligibility search-time

zone, respectively.

The reference peak is the largest peak found within the eligibility time zone.

Its

time should be identical to one of the components listed in the compound table

(see Chapter 3).

adjusted retention

peak is not found in the search zone, relative retention times of all peaks will be reported
If all

peaks are unknowns, a dummy reference peak can be set to one second.

If the

as zero.

This fulfills

the requirement that a reference peak be specified.

Your parameters to RPKT and RRT must be within the range 1-4095 seconds, and TBEG

and

TEND must be within the range 0-4095.
Your response could be
RPKT, RRT, TBEG, TEND
which satisfies the requirement.

__i ^000,1,1 ,:

The relative retention time, 1000, is equivalent to 1 .000.

Building a method may, from this lengthy discussion, seem complicated

However, the lengthy discussion only represents the services perfonned by Monitor

and time consuming.

and the system. Your

printout to this point might appear as follows.

ENTER, 13>
--3,25,:

INST, PK CT
UNK, FF, SMPR
RI-YP, AF
IS

--1, j^g^
--0,100,":
--1,
.

TM/SCALE

RPKT, RRT, TBEG,

TEND

--1,1000,1,1,:

This represents about one or two minutes of your time.

Conversation proceeds to the next question, below.
F TM,

CODE, VAL

where F means function and

= the time at which the function is implemented (0-4096 sec.)

CODE = a code defining the function (see Table 1)
VAL

- a numerical value applicable to most functions

2-6

Your reply to TM is faken as seconds and must be within the range 0-4095.

The function

codes and applicable values should be taken from Table 1

Table 1
Functions
Function

Allowable
Value

Explanation

Code
Terminate Run .

This is always the last function in the

Default

Value

null

method; e.g.

—2016,0,0,:
at 2,016 seconds end analysis and type report.

Maximum

run length is 4096 seconds.
Start

Peak Search

Commence searching for peaks; e.g.

nul

"2,1,0,:
start accumulating data at 2 seconds into the run.

Stop Peak Search.

Suspend search for peaks, continue

ignoring peaks until the next function code 1

nui

activated;

e.g.,

-1,1,0,:
—25,2,0,:
—50,1,0,:
This sequence sets a time window from 25 to 50 seconds

from the beginning of the run during which data is ignored.

Autobase Threshold . This controls the degree of stability
which the signal must exhibit before Monitor declares it to
be a true baseline. For a signal to be declared baseline it
must not exceed the amplitude threshold (code 4) for the
length of time specified by the autobase (code 3): e.g.

1-255

seconds

—1,3,10,:
—540,3,45,:
At 1 second the autobase time is set to a value of 10 seconds, and at 540 seconds the autobase time is reset to 45
seconds

Amplitude Threshold .
detecting peaks.

This is the first stage sensitivity for

It is a measure of the departure from

baseline that the new peak must undergo in order for the
system to consider the rise as a new peak. A threshold
factor of 1

most sensitive; e.g .,

-58,4,1,:

—125,4 4,:

2-7

0-12

Table 1 (Cont)
Functions

Function

4 (cont)

Allowable
Value

Explanation

Code

Default

Value

Increase the amplitude which a peak must exhibit to be
recognized as a peak from a value of 1 to a value of 4
125 seconds into the run.

Slope Threshold. This is analogous to amplitude threshold with regard to shoulder sensitivity. A sensitivity of
5 is very sensitive, 40 is quite insensitive.

0-255

Zero has the

special meaning of ignore shoulders; e.g.,

-1,5,10,:
—205,5,0,:
—410,5,40,:
At 1 second, set shoulder sensitivity to be quite sensitive;
at 205 seconds, ignore shoulders until 410 seconds; then
set shoulder sensitivity to be insensitive.
Time Filter Period . This isthe anti-noise spike control, pro-

1-15

tecting the system against false peaks and shoulders. When the

(1/2 sec)

signal rise penetrates the amplitude threshold, the system monitors the rise, treating it as a probationary peak. At the conclusion of the time filter period (code 6), the peak rise must be

above the basel ine by a value greater than the threshold specified by code 4 and the slope must not have gone negative. In
this time period the peak must have accumulated an area equal
to or greater than that specified by code 9. If the time between
a shoulder's two inflection points does not exceed the time filter period, the false shoulder is rejected. Therefore, the larger

the filterperiod the greater the protection. However, too large
a period will result in a loss of peaks of short duration and of

shallow shoulders. This parameter is stated in 1/2 seconds. See

Appendix D.
Peak Termination Time : This code protects the system from
being confused by a falling baseline at the end of a large
peak. With this code, one can set a time-after-crest at
which a peak is arbitrari ly terminated. This is also very useful

when applied |ust before the analysis termination func-

tion (code 0).

It assures that

a peak which is eluting at

run termination time is included in the report.

(If the peak

had not gone back into baseline at run termination, the
peak can be terminated using code 7 with a value of just
before run termination.) e.g.,

—409,7,0,:
—410,0,0,:

2-8

0-255

4095

Table 1 (Cont)
Functions

Function

Allowable
Value

Explanation

Code
8

Fix Baseline

baseline.

This function is effective against a drifting

Default

Value

nu II

When implemented, the next valley found is

called baseline.

Area Threshold Factor This is the third sensitivity control
Area threshold is the area which a peak must have within
the time period set with code 6 to be recognized. See

0-15

Appendix D.
10

This function is used when some
automatic control is desired. The value of the octal integer

Opt ional Relay Output.

0-7

(0-7) is interpreted as a 3-digit binary number in which

each digit is 1 or 0, according to whether the corresponding
digit is set or reset; e.g.,
--400,7,0,:

—401,10,1,:
—500,10,0,:
For 100 seconds, between 401 and 500, we have used relay

The value of this function is
number 1 to flush the column
interpreted in binary as shown below.
.

3--Digit Binary

Octal Value

000
1

001

010

Oil

100

101

6
7
11

111

This function is used to change the current filter factor to
the value specified ibr this function. Filter factor is used

1-4095

to control the system's sensitivity to slowly rising peaks by

improving the signal to noise ratio
amplitude rises (or falls) less than 3
.

In general , if the peak's

\N sample (on a x 10

will be
amplifier), the use of a filter factor greater than
process,
smoothing
essentially
a
necessary. Since filtering is

will tend to decrease the system's sensitivity to quick peaks
and short baseline segments. Hence, a high filter factor
it

should be used only for that portion of the run where long,
small peaks or shoulders are expected. With a filter factor of
can be
5, peaks of 100 pV high with a 200-second duration
consistently detected.

At designated times during the analysis, certain parameters are changed or
tutes a functional decision according to the function code and

2-9

its

the system insti-

corresponding value.

Monitor repeats this question until the function code
next question .

entered, it then proceeds to the

Your response to these questions might be as follows.

F TM,
F TM,

F TM,
F TM,
F TM,
F TM,
F TM,
F

TM,

CODE,
CODE,
CODE,
CODE,
CODE,
CODE,
CODE,
CODE,

VAL
VAL
VAL
VAL
VAL
VAL
VAL
VAL

--1W,0,:

^'^

--1,3,10,:
--1,4,1,
--1,5,0,
--1,6,2,
--1 ,9,

(2)

(3)

(4)
(5)

- -3999, 7, P)

(6)
,

--4000,0,0,:

(7)
(8)

The parenthesized numbers 1 through 8 are to aid you in following the discussion below.
Analysis commences upon depression of the LOG START pushbutton, and time

taken from that moment.
1

At one second into the analysis accept chromatographic data and accumulate

At one second, the autobase threshold is set to 10 seconds.

At one second, the amplitude threshold is set to 1 , i.e., very sensitive

(in seconds) is

The above analysis would perform as follows:
peaks.

At one second, the slope threshold is set to 0, i.e., ignore shoulders

At one second, the time filter (protationary) period is set to one second

(value is stated

in 1/2 seconds).

At one second, the area threshold is set at one second.

At 3999 seconds, terminate the peak.

At 4000 seconds, cease accepting chromatographic data and commence
8.
generating the
analysis report using the data accumulated.

Upon recognizing the

or null function code in the previous question. Monitor types

TM, NAME, TOL, RF, CWT
where

- adjusted retention time of the component NAME (allowable input
0-4095 seconds)

NAME

= component name (up to six characters, the first must be a letter)

TOL

= time tolerance (in seconds) for searching for the component; plus and
minus this number is the time window in seconds encompassing the TM
(1-99)

NAME

The largest peak found within this tolerance is the component

If the tolerance is greater than time, then it will be automati.
cally adjusted to equal time.

= response factor (0-32767)

CWT

= component weight percent in the calibration sample (for area normalization analyses) or component weight in the calibration sample (for internal
standard analyses) (0-32767) (see Chapter 3).

2-10

The component time tolerance

Here is where you identify and name all expected components.
is the zone on

either side of the stated retention time in which peaks are considered as potential

for the component .

matches

The largest peak is selected in the case of multiple candidates. Other peaks found

in this window are called

unknowns.

Overlapping component zones (windows) are permitted and are often very useful
must be taken because of the convention mentioned in the above paragraph

Response factors are scaled such that 10000 is equivalent to 1 ,

Caution

(underlined sentence)
.e. , there is an implied

decimal point four places from the right.
If the calibration weight is set to 0,

the system does not update the response factor of that

type of
component during a calibration run. The value assigned to C\A/T is taken according to the
calculation (RTYP) specified.

For an area normalization type method (RTYP=0), the value of CWT is

taken as the component weight percent in the calibration sample.

For internal standard (RTYP = 1) and

weight of the
external standard (RTYP =2) methods, the value of CWT is taken as the

component.

Monitor will repeat the above question until your response is a single colon.
response defines one component in the sample.

Each complete

Therefore, if you wish to identify three components in

the sample, you should respond correctly to three questions.
If you

were building a method to analyze a compound for all unknonws, you would respond

as follows.

TM,NAME,TOL,RF,CWT

—1, PEAKS,! ,0,0,:

TM,NAME,TOL,RF,CWT

—

This honors the requirement for a reference peak and an internal

standard peak, although no peak will

be found at 1 second; all peaks will be printed out as unknowns, thereby providing

exact retention

times for precise method building.

There must always be a component in the compound table whose time corresponds

exactly to

the time listed for the internal standard and reference peaks.

Upon receipt of the single colon (null input). Monitor terminates the method building
and stores the method on the disk for later use.

2-11

session

The printout of the method we've just built appears below.

ENTER, 13>
--3,25,
--1,1,2^-

INST, PK CT
IJNK, FF, SMPR
RTYP, AF
IS

-0,100,1

TM/SCALE

--1,

RPKT, RRT, TBEG, TEND
TM, CODE, VAL
TM, CODE, VAL
TM, CODE, VAL
TM, CODE, VAL
F TM, CODE, VAL
F TM, CODE, VAL
F TM, CODE, VAL
F TM, CODE, VAL
TM, NAME, TOL, RF, CWT
TM, NAME, TOL, RF, CWT
F
F
F
F

--1,1000,1,1,:
--1,1,0,:
--1,3,10,:
--1,4, 1,
--1,5,0,
--1,6,2,
--i^g^i"^

--3999,7,0,--4000,0,0,:
- - ,PEAKS,
,
1

--:

This method would be used to report all components as unknowns,

2.3

ANALYZE COMMAND
This is the command used to initiate an analysis.

As stated earlier, to perform an analysis

you need a method, and each method, except method 0, is assigned to a specific
Therefore, the method and chromatograph numbers are the parameters to the

chromatograph

ANALYZE command

For

example,

ANALYZE, 13,3,:
tells A/bnitor that you wish to analyze a sample using

method 13 on chromatograph 3

after you type the line terminator, the colon. Monitor makes the following

Immediately

checks,

a .

method 13 stored on the disk ?

method 13 assigned to chromatograph 3?

Is chromatograph

there sufficient storage avai lable on the disk to hold the chromatographic

the system able to handle this analysis (no more than 240 data points per
second can

(This check would not be made on method 0.)

3 free and available for this analysis?
data ?

be specified at any one time)*?
If Monitor gets a

"no" answer to any of the questions above, it types an error message

indicating which condition cannot be met (see Appendix C)
If all

conditions can be met. Monitor transfers method 13 from disk storage into core
memory

and asks the following question
ID, RCYCL

*200 points per second for 50 Hz power

2-12

which asks you to identify or name the analysis and to specify
core for use with subsequent samples, i.e., whether

you plan to recycle or repeat the analysis.

For ID, the first parameter, your response is

begins with an alpha character (a letter) and does not
tifier will

whether you want to hold method 13 in

completely arbitrary if your identifying name

exceed 16 alphanumeric characters. This iden-

appear in the header section of the typed analysis report;

uniquely identify each separate analysis.

It is

therefore, care should be taken to

recommended that you identify the analysis according

to your filing procedures.

For RCYCL, the second parameter, your response

must be either

or 1 , where

= single analysis; return method to disk storage after this analysis run.
1

= multiple analyses; until LOG CLEAR pushbutton is pressed, retain method in

samples are LOG controlled)
core for succeeding sample analyses (succeeding

Assume the following parameters and your printout will be as shown

ID,

ANALYZE^ 13,3;.
A GLC-8 DEMO,
10000:

RCYCL

NORM

:
1

Monitor scans method 13 to determine the type of calculation
standard, or internal standard) before asking the next
If it is normalization.

below.

(normalization, external

question.

Monitor asks NORM, to which you should specify the desired

component weight percent to be reported.

total

A response of 10000 is equal to 100%, so that the sum of

for 9000, the sum will total 90.
the reported component weight percent will total 100;

Your parameter

must be within the range 0-40959.
If it is external

standard. Monitor asks EX STD.

10000, and the resulting number is multiplied by the
reported.

A response of 10000 is normally used.
If it is internal

It then

takes your response, divides it by

actual component weight percent of each compound

Your parameter must be within the range 0-40959.

standard. Monitor asks SAMP WT, STD WT, and waits

enable scaling during the
total sample and internal standard weights to
analysis.

Your parameters must each be within the range 0-40959.

values entered for total sample and internal standard

for you to specify the

post-sampling phase of the

If the

run is a calibration, the

weights are not used in the calculation.

When Monitor is satisfied with your responses (if an error is made. Monitor
the Teletype reverts to the "free" state (to command

repeats the question),

mode, available for another command), and the

READY light on the LOG associated with chromatograph 3 is
injection.

2-13

lit.

The system is now ready for sample

As stated earlier, it is very important that you depress the LOG
after sample injection.

START pushbutton immediately

This is repeated here because a major cause of component-peak

tion is not only the proportional delay due to column aging

misidentifica-

but also the delay due to the variation of

timing between sample injection and START pushbutton depressi

ion.

CALIBRATE COMMAND

2.4

The CALIBRATE command is similar to the ANALYZE command in
questions and both commands are used to execute an analysis

that Monitor asks the same

run and to generate an analysis report.

When Monitor is in command mode the calibration run may be initiated by

typing

CALI,13,1,:
where CALI is CALIBRATE abbreviated, 13 is the method number, and

The procedures for CALIBRATE and ANALYZE are identical in that they
either

the chromatograph number.

both ask for ID,

RCYCL and

NORM, EX STD, or SAMP WT,STD WT.
A calibration calculates the response factors and updates them in the compound table

in the

method (see Chapter 3)
Response factors of components with zero calibration weights are

ponent with an assigned calibration weight is not found, the
nent response factors are not updated in the method.

If any

com-

calibration run is invalid and the compo-

This condition is indicated in the report when the

response factor and component percent columns are empty.
ard peak

not updated.

normalization analyses the internal stand-

used to scale all other component response factors.

Consequently, its response factor is

always 10000 (or 1.000).

2.5

MODIFY COMMAND
The MODIFY command allows on-line modification of a method. When
Monitor is in command

mode (i .e., when it has spaced toward the center of the Teletype paper)

it is

waiting for you to type one

of its seven commands, in this case the MODIFY command.

Assume you want to change the parameter to RTYP in method 13, which
using the ENTER command.

was built earlier

You would type,

MODIFY, 13,:
where 13 is the number of the method to be modified. When you type
the colon to terminate the line.
Monitor retrieves a copy of method 13 from the disk and types the first

line of the method:

MODIFY,13,:

INST,PKCT

"3,25,

2-14

and waits for you to either change one or more parameters or to type a colon which tells Monitor to
leave that line unaltered and type the next line,

UNK,FF,SMPR
and waits for you to type,

—1,1,2,

RTYP is on the next line so you then type another colon and Manitor types
.—0,100,

RTYP,AF
If you want to specify

an external standard calculation, instead of the present area-normalization

calculation, you then type 2,100,: Monitor would accept the change and type the next line.

The

printout to this point appears below.

M0DIFY>13^
--3,25,
--1,1,2,
--0,100,2,100,:
:

INST, PK CT
UNK, FF, SMPR
[^YP, AF
IS

--1'

TM/SCALE

Monitor will type the next line in the method and wait for you to type the line terminator.
This will continue until you have typed a colon after the last line in the method, whereupon Monitor
will return the modified method to disk storage for subsequent retrieval

However, after all modifications have been made, the typing out of the rest of the method
can be hastened by placing a punched paper tape of colons in the Teletype reader and setting the reader
switch to START .

When Monitor types a line it will accept a colon from the paper tape reader and

commence typing the next line, accepting subsequent colons from the paper tape reader until the entire
method is typed.

(Procedures for punching the paper tape of colons are in Appendix C of the PDP-8/i

System User's Guide.)

NOTE
parameter on a line is to be changed, all parameters
on the line must be re-entered In the case of function and
component entries, no entries can be added or deleted, but
If one

only changed.

2.6

DUMP COMMAND

A copy of a method or a group of methods can be obtained using the DUMP command

This

command enables you to have a copy of one or more methods typed on the teleprinter and, if desired,
simultaneously punched on paper tape using the Teletype punch .
If, for example, you want a printed copy of method 13 for your files and also a punched

paper tape copy for your method library, you would type (with Monitor in command mode and the paper
tape punch ON) the following.

2-15

DUMP, 13,:
(The Teletype operating procedures in the PDP-8/l System User's Guide instruct you on how to generate
leader/trailer tape, when to depress the Teletype punch

ON button, and why these actions are

performed.)
If you wanted to dump methods

8, 9, 10, 11, 12, and 13, you would type

DUMP, 8,13,:
and methods 8 through 13 would be copied inclusively.

When a method to be dumped is busy, e.g. , being used in an analysis. Monitor types mn

METHOD BUSY (mn is the method number) and returns to command mode.

For example if, after dump-

ing methods 8 and 9, Monitor types

10 METHOD BUSY
the dumping session stops. Monitor returns to command mode, and waits for your next command.

The method is copied exactly as it was entered onto the disk, except that Monitor will
double space between lines as it types the method.

2.7

DELETE COMMAND
The DELETE command is used to erase one or more methods from the disk.

When a method

no longer needed it can be deleted from the disk, allowing more storage for additional new methods.

DELETE requests are written in the following format:
DELETE, 13,:

when only one method is to be deleted, or
DELETE,8,13,:

when a group of methods is to be deleted.

If an attempt is

made to delete a busy method, /Vfenitor

types mn METHOD BUSY (mn is the method number) and returns to command mode, as explained in

the previous section (DUMP Command)

2-16

CHAPTER 3

USING GLC-8
Perkin-Elmer 900

This chapter Is a description of an actual analysis using GLC-8 and a

Chromatograph with a chromatogram.

Here, we will start from "scratch" by building a method 0,

this
which you need do only once. Actual Teletype output is used, and each step performed during

the chapter.
analysis is illustrated in Figure 11, System Operation, concluding

We will assume that the chromatograph and chromatogram are calibrated and ready for use,
that the system is loaded and started as described in Appendix A, and that

the date and time as explained in Section

we have initialized with

.5.

This run is to establish a calibrated method for future quality control analyses

type of sample.

has been previously analyzed manually, therefore, the components are known and

can be identified by comparing our strip-chart recording to those obtained from

3.1

of the same

the GLC-8.

ASSIGN CHROMATOGRAPH AND TELETYPE
First

we must assign the chromatograph (number 1) we intend to use to our Teletype (number 2)

This is done when we type

ASSIGN^ 1^2^

3.2

ENTER METHOD
All other methods must be assigned to a specific chromatograph; the

and numbered

reserved for use with any chromatograph

In this example we will use method

using the ENTER command.

for an area normalization analysis,

RTYP=0,

(normalization type calculation)

UNK =

1 ,

and it is built

The specified control parameters (filter factor and functions) are at your

discretion, however, we have found the following guidelines to be

method that is built

helpful

.0 response factor for unknowns)

dummy internal standard

IS TAA/SCALE = 1 ,:

RPKT, RRT, TBEG, TEND = 1, 1000, 1,1,:V. and reference peak

The last entered F

TM, NAME, TOL,

TM, CODE, VAL = 4000,0,0,:
RF,

CWT = 1, PEAKS, 1,0,0,:

(only one entered:

this is a

dummy reference and internal standard peak to correspond with c and d, above.)
This analysis will run for 4000 seconds or until the

LOC STOP pushbutton is pressed.

reported as UNK (unknowns) with their area percent listed in the report.

3-1

All peaks will be

Our method

built as follows because we want to see all components in our

ENTER, 0, 3,
--1,15,

INST^ PK CT
UNK, FF, SMPR
RTYP, AF

--1, 1,2,
--0, 100,
--1,
-- , 1000, 1,1,:
:

IS TM/SCALE

NAME,
NAME,

TOL>
TOL,

TEND

--1,1,0,:
--1,3, 10,
--1,4,1
--1,5,0,
--1,6,8,
--1,9,1 ,:
--3999, 7,0,
--4000,0,0,
--1 , PEAKS, ,0,0,
:

CWT
CWT

RF ,
RF ,

Figure 4

If any parameter is

RPKT:. RRT, TBEG,
F TM^ CODE, VAL
F TM:, CODE, VAL
F TM^ CODE, VAL
F TM:, CODE, VAL
F TM, CODE, VAL
F TM, CODE, VAL
F TM, CODE, VAL
F TM, CODE, VAL

TM,
TM,

compound.

- - :

Method

not clearly understood, refer to Chapter 2 for a thorough explanation.

DUMP METHOD

3.3

When method

has been decided upon and built it may be dumped on the Teletype

and punch for future reference and use.

printer

This is done when we type

DUMP,0,

When dumping onto paper tape, depress the Teletype punch ON button, and then type
DUMP,0,:

(see

PDP-8/t System User's Guide for additional information).

When a method is built it is stored on the disk, and a copy of the method is transferred from
disk into core memory when it is "called" with any but the ENTER
command, as when we type DUMP,

0,:

3.4

Method

is still

on the disk and available for subsequent use

ANALYZE WITH METHOD
With the chromatograph and chromatogram calibrated for use and method

on the disk, we are ready to run our analysis.
(identify) the analysis run,

First,

we call method

built and stored

into core memory,

name

and specify whether we wish to hold the method in core memory for use on

succeeding runs (recycle).

3-2

ID:.

ANALYZE>0j 1^
DEMO>]STRATION

RCYCL

1^0.,:

10000:

NORM

method
Our command and response was correct because we didn't get an error message. Therefore,
is on

universal method, available
the disk and available for use on chromatograph 1, since it's the

to any connected chromatograph .

Monitor also accepted our identification and recycle parameters

Immediately after typing the second colon, above, the READY light on the LOG
with chromatograph

associated

indicating that the system is ready for sample injection.

lit,

We inject our sample and immediately press the LOG START pushbutton to start the
analysis run.

Ghromatograph attenuation may be manually changed at any time without affecting the
chromatographic input to GLG-8.
Since method

built to run 4000 seconds, visual inspection of the chromatogram

indicates when the compound has passed through the column (Figure 5).

terminate the run by pressing the LOG STOP pushbutton.

output

At this time, we manually

This causes GLC-8 to generate and type

the analysis report (Figure 6)

Since we are looking for all components of the sample, we did not identify

expected peak, therefore, in the analysis report all component peaks

by name any

are printed as UNK for unknown.

Gompare the strip-chart recording with the analysis report and select the peaks of

interest.

We see from the report that 11 peaks (numbered in parentheses) were detected—some aren't visible
We are interested in only seven of the reported peaks, those numbered
the strip-chart recording

2,3,5,6,7,8, and 9.

We note that in this case they are all

The analysis revealed three peaks of no interest.
very small peaks.

to a value of two
Increasing the minimum peak area (code 9) from a value of one

should result in disqualification of these unwanted peaks.

3.5

ENTER METHOD 23

We now use the analysis report to build our unique method.

method already on the disk. Ours will be

method is arbitrary, as long as the number isn't assigned to a

method 23, and it is method X in the flow chart of Figure 1 1

The number we assign to this

Method 23 is shown in Figure 7 and is

explained below.

Method 23 was built from method 0, therefore, only the changes need be
itemized below correspond to the parenthesized numbers in

noted; the numbers

Figure 7.

1 .

Looking for the seven peaks of interest only.

We chose an arbitrary peak as our internal standard peak, even though this is a normal-

ization report

3-3

—

= X32 atten.

a
o
o

E
1

K 32 atten.

E
u

^X 256 Often.
1

•

—

F^^

—

^:5l2atten.

ir
-|

K 16 atten.

-T

c
E

1
1

Y Op
£."
-A
o ^*i^
ui le n. —
1
1

Figure 5

Chromatogram Recording

— X32 atten.
1

ANALYSIS
DATE

INST

DEMONSTRATION
COMPONENT

TIME

1333

METHOD

NORM

10000

RRT

TIME

COMP%

RF FACT

TOL

PEAK AREA

TYPE

0000

.006%

(1)

0000

5.608%

(2)

PEAKS
UNK

.000

8075

UNK

.000

6612

UNK

.000

107

4065748

0000

3.448%

(3)

UNK

.000

168

93367

0000

.079%

(4)

UNK

.000

192

24032

0000

20.381%

(5)

UNK

.000

235

5557

0000

4.713%

(6)

UNK

.000

304

36508

0000

30.963%

(7)

UNK

.000

349

16712

10000

14. 173%

(8)

UNK

.000

387

23769

10000

20. 159%

(9)

UNK

.000

406

547316

10000

.464%

(10)

UNK

.000

510

10000

.000%

(11)

Figure 6

Area NormalizaHon Analysis Report

Explained in Section 2.2.

Started data acquisition here.

Increased the value from one to two to eliminate

unwanted peaks.

Create baseline point.

Terminate analysis run and generate analysis report.

This is the component table .

The component weights correspond to the weight

of the components in our known sample.

Now we have built a customized method, identifying the peaks

3-5

of interest.

percents

ENTER, 23,
--1,7,
--1,1 ,2,

INST, PK CT
UNK.. FFj SMPR
RTYP., AF
IS

RPKT, RRT>

TM,
TM,
TM,
TM,
TM,
TM,
TM,

TBEG, TEND

NAME, TOL,
N/^ME, TOL,
NAME, TOL,
NAME, TOL,
NAME, TOL,
NAME, TOL,
NAME, TOL,

RF,
RF,
RF,
RF,
RF,
RF,
RF,

Figure 7

3.6

-~0, 100,
--192,
--304, 1000,280,320,
--1, 1,0,
--1,3, 10,
--1,4, 1,
--1,5,0,
--1 ,6,2,
--1 ,9,2,
--409,7,0,:
--410,0,0,
--32,A1,10, 10000, 767,:
--107,A2, 20, 10000, 471,

TM/SCALE

F TM, CODE, VAL
F TM, CODE, VAL
F TM, CODE, VAL
F TM, CODE, VAL
F TM, CODE, VAL
F TM, CODE, VAL
F TM, CODE, VAL
F TM, CODE, VAL
TM, NAME, TOL, RF,

(1)

CWT
CWT
CWT
CWT
CWT
CWT
CWT
CWT

-- 192, A3, 20, 10000,208
7,
--235,A4, 15, 10000, 5 62,:
--30 4, A 5, 18, 10000,2941,
--349,A6, 15, 10000, 1363,
--38 7, A 7, 20, 10000, 1809,

(2)
(3)
(A)

(5)
(6)
(7)

)

(8)

Method 23 Before Caltbrat ion

CALIBRATE METHOD 23

Our method must now be calibrated to update the response
the CALIBRATE command and responses as shown

ID,

This is done by typing

below.

CALIBRATE, 23,1,
CALI DEMO 3,0,
10000:

RCYCL

NORM

With our input correctly entered, the LOC READY light
our calibration analysis run.

factors.

comes on; the system is ready for

We inject our sample and immediately press the LOC START pushbutton

and the calibration analysis run commences. After
410 seconds the LOC COMP light comes on and
the calibration report shown in Figure 8 is

3.7

typed.

DUMP METHOD 23
During calibration, GLC-8 automatically updates

response factors.

method 23 to contain the reported

Method 23 is now complete and may be dumped on the Teletype

for future reference and use.

printer and punch
Method 23 is still stored on the disk and is available for future

analyses

of the same sample

3-6

Notice In the print-

We dump method 23 when we type DUMP,23,:, as shown In Figure 9.
out that the response factor parameters have

been updated

CALIBRATION
DATE

INST

TIME

METHOD

1350

NORM

10000

CALI DEMO 3

TOL

PEAK AREA

TYPE

RF FACT

COMP%

8090

16784

767

41%

4990

17839

47 1

41%

.646

201

41422

10000

2087

22%

.781

243

6632

16049

562

16%

TIME

COMPONENT

RRT

.1 18

.379

A3
A4
A5

.000

311

36425

15817

2941

.144

356

19247

14268

1363

.263

393

22503

15225

1809

14%

Figure 8

Calibration Report of Method 23

DUMP>,23,: _„
--

INST, PK CT
UNK, FF;. SMPR
RTYP, AF
IS

TM/SCALE

RRT, TBEG, TEND
CODE, VAL
CODE, VAL
F TM, CODE, VAL
F TM, CODE, VAL
F TM, CODE, VAL
F TM, CODE, VAL
F TM, CODE, VAL
F TM, CODE, VAL
TM, NAME, TOL, RF, CWT
TM, NAME, TOL, RF, CWT
TM, NAME, TOL, RF, CWT
TM, NAME, TOL, RF, CWT
TM, NAME, TOL, RF, CWT
TM, NAME, TOL, RF, CWT
TM, NAME, TOL, RF , CWT

RPKT;,
F TM,
F TM,

Figure 9

ENTER, 23, 1,
7,
1,

•

1,
1,

.._

100,

•

192,
30 4,

1000,

280,

3,
4,
5,
6,

10,

-----------

1,
1,
1

1 ,

1,
1,

__
__
-- -

409,
410,
32, Al

192, A3
235, A 4
30 4, A5
349, A6
387, A7

10 7,

10,

y
9

2,
2,
0,

320,
*

Method 23 After Calibration

3-7

20,
20,
15,
18,
15,
20,

767,
6784,
471 ,
17839,
10000, 2087,
562,
16049,
15817, 2941,
14268, 1363,
15225, 1809,

3 .8

ANALYZE WITH METHOD 23
Mefhod 23 Is now calibrated and ready to control the analysis of

this is

where you'll start when analyzing with method 23; it will always

our sample.

From now on,

be stored on the disk and

available for use merely by typing ANALYZE, 23,1,:.

To perform the analysis of our sample using the calibrated

method, we need only type the

ANALYZE command and respond as shown below.
ID,

ANALYZE, 23, 1,
ACTUAL ANALYSIS, 0,

RCYCL

NORM

10000:

The LOC READY light comes on, indicating that the system
after injecting our sample we press the

ready for sample infection.

Immediately

LOC START pushbutton and the analysis commences.

410-second run the LOC STOP light comes on and the analysis

After the

report is typed by Monitor.

ANALYSIS
DATE

INST

TIME

METHOD

1410
23

NORM

ACTUAL ANALYSIS

igggg

COMPONENT

RRT

TIME

PEAK AREA

TYPE

RF FACT

COMP%

. 1

8040

16784

7.671%

42%

.379

5522

17839

4.701%

38%

.6 48

201

41045

10000

20.872%

25%

.780

242

6687

16049

5.620%

15%

TOL

.000

310

36164

15817

29.413%

.141

354

19195

14268

13.630%

12%

.264

392

22392

15225

18.093%

12%

Figure 10

Actual Analysis Report Using Method 23

Figure 11 provides a flow chart summarizing the analysis

3-8

performed in this chapter.

)

INITIALIZE

ASSIGN

TTY
..
DENOTES
SAMPLE INJECTION

ENTER METHOD

-ANALYZE

REPORT

Jl
^..-^EAKS^^ NO
<r REPORTED J>

—

MODIFY

METHOD

—

YES
BUILD METHOD X

NAME

COMPONENTS

--CALIBRATE

METHOD X

REPORT

MODIFY METHOD X

YES

Fl NISHED

Figure 11

System Operation

3-9

•^ANALYZE

APPENDIX A

LOADING AND STARTING PROCEDURES
The GLC-8 program is furnished on a punched paper tape and

loaded into core memory

optional high-speed photoelectric reader.
using the paper tape reader, either Teletype or the

system program is loaded into core memory, optionally

The

saved on the disk, and initialized for use as

outlined below.

The Disk Bootstrap Loader is used to load GLC-8 to and from disk
The GLC-8 system program tape is punched in binary coded

and core.

format, therefore,

it is

loaded

into core using the Binary (BIN) Loader.

NOTE
For computer and Teletype console operations see
PDP-8/I System User's Guide, DEC-08-NGCB-D.

A.l

LOAD AND START
a.

Load the Read-In-Mode (RIM) Loader (see PDP-8/l System

Load the Binary (BIN) Loader (see PDP-8/l System User's

Press the STOP switch

Put the program tape into the paper tape reader.

Set the switch register (SR) to 7717. press LOAD ADD

switches.
electric reader, reset SR to 3777), and then START
the tape reader and stop when about half of the tape
f.

Guide).

(if using

Press the

the highspeed photo-

The tape will start reading in through

has been read in.
If it does,

Check the accumulator (AC), it should not have any bits lit.

has not been read in correctly and you must start
g .

User's Guide).

the program

again at step b above.

CONT switch and the tape begins reading in again

When the tape stops

GLC-8 is in core.
does, start over at step b, above.

Check the AC, it should not have any bits lit.

Press the STOP switch.

j .

press LOAD ADD and then
Set the SR to the starting address of GLC-8 (presently, 6623),

GLC-8 will type the version number of the system program and MONTH,

If it

START.

HOUR, MINUTE, and wait for your response.

A-1

DAY, YEAR,

LOAD ON DISK AND START

A. 2

The Disk Bootsfrap Loader is used to transfer GLC-8 from
a.

After performing steps a through

Put the Disk Bootstrap Loader tape in the paper tape

Set the SR to 7756, press LOAD ADD and then

in section A. 1 ,

core onto disk.

above, proceed to step b, below.
reader and set the reader to START.

START switches. Wait until the tape has

read in; then proceed to step d.

Press the STOP switch.

Set the disk write-lock switches:

be seen by removing the disk cover.
f
.

DISC

and upper 16K to OFF. These switches can

(See GLC-8 Maintenance Manual,

Set the SR to 7702, press LOAD ADD and then

from core onto disk and the PAUSE light will come

DEC-08-HGAA-D.)

START. The system will be transferred

on.

Press the STOP switch.

Set the disk write-lock switches:

DISC

and upper 16K to ON.

Set the SR to the starting address of GLC-8

(presently, 6623), press LOAD ADD and then

START.
i .

GLC-8 will type the version number of the system program and

MONTH, DAY, YEAR,

HOUR, MINUTE, and wait for your response.

LOADING FROM DISK INTO CORE

A.3

The Disk Bootstrap Loader is used to transfer GLC-8 from disk

into core.

With GLC-8 on

the disk, perform the following steps.

Load the RIM Loader.

Press the STOP switch

c
.

Put the Disk Bootstrap Loader tape in the paper

tape reader and set the reader to START

Set the SR to 7756, press LOAD ADD and then

START switches; wait until the tape has

read in, then proceed to step e.

Press the STOP switch.

Set the SR to 7700, press LOAD ADD and then

Press the STOP switch

Set the SR to the starting address of GLC-8 (presently,

START.

6623), press LOAD ADD and then

START.
i
.

GLC-8 will type the version number of the system program and MONTH,

HOUR, MINUTE, and wait for your response.

A-2

DAY, YEAR,

m
*

Load RIM
ord BIN

\
fPDP-8/I System User's Guide
Figures

RIM-l-3,BIN-ia2

LoadGLC-8 Tape
Using BIN

PDP-8/I System User s
Guide. Figures RIM-1-3
(forRIM);FigureBIN-1
for Disk Loader

YES

Press STOP

Load Disk

Set

Bootstrap Loader
Using RIM

STOP

Press

SR=SA

Presently,

SA=6623

GLC-8

Press LOAD ADD
and thenSTART

Set Disk Switches]

GLC-8 Types
Response

Initial

1
'

Set

Section A-2

SR = 7702

Enter Date
|

and Time

Press LOAD ADD

and thenSTART

System Pouses

A noticeable pause;
the failsafe facility
is recovering methods

Set Disk Switches

on the disk.

Teletype Spaces to
Center of Paper

C
Figure A-1

Enter a

Command

)

Loading and Starting Procedures

A-3

^
P DP- 8/1 System User's Guide
Figures RIM-1-3 (for RIM)

Load Disk
Bootstrap Loader
Using RIM

Figure BIN-l(for Disli Loader)

Press STOP

Set SR = 7700

SA of Disk Bootstrap Loader

Press LOAD ADD
and then START

Press STOP

Set
of

SR=SA

Presently,SA=6623

GLC-e

LOAD ADD
START

Press

and then

(GLC-8 Types >
Initio

Responsey

Enter Date

and Time

A Noticeoble Pause, the Fail

System Pause

safe Facility is Recovering

Methods on the Disk
Teletype Space to
Center of Paper

Enter a

Commond

Figure A-2

Loading GLC-8 From Disk Info Core

A-4

APPENDIX B

SUMMARY OF COMMANDS, QUESTIONS, AND RESPONSES

MONITOR COMMANDS

B.l

parameters
The seven Monitor commands with the required parameters are listed below. The
are coded as follows:

= method number (0-99)

= questions (0 = type; 1 = do not type)

= chromatograph number (1-64)

= Teletype number (1-9)

Command

Explanation

Format

ASSIGN, en, tn,:

ASSIGN

Assigns subsequent reports of chromatograph en
to be typed on Teletype tn.

ENTER, mn, q,:

ENTER

Used to build and enter a new method onto the
disk.

ANALYZE, mn, en,:

ANALYZE

Method mn will be used on the analysis of
chromatograph en

MODIFY

MODIFY, mn,:

Method mn is typed line-by-line, pausing at
the end of each line for parameter modification.

CALIBRATE

CALIBRATE, mn, en,:

Performs a calibration analysis on method mn using

chromatograph en.

DUMP

DUMP, mn, mn,:

Copies of methods mn through mn are typed on
the Teletype and/or punch; for only one method,
omit the second parameter.

DELETE

DELETE, mn, mn,:

Deletes methods mn through mn from the method
library; for only one method, omit the second

parameter.

B.2

QUESTIONS AND RESPONSES

B.2.1

ENTER

Explanation and Responses

Questions

INST, PK CT

Instrument (chromatograph) number (1-64).
number of peaks which will stop the
Peak count

—

run (1-200).

B-1

Questions

ExplgnaHon and Responses

UNK, FF, SMPR

Response factor applied to unknowns (0-2):

= apply response factor of
= apply response factor of 1
2 = apply response factor of last identified peak
1

Filter factor

~ digital smoothing (0-7):

= none; 7 is maximum;

typical

Sampling rate:

2
3

4
5

RTYP, AF

60 cps

50 c£S

03.75
07.50
15.00
30.00
60.00

03.125
06.250
12.500
25.000
50.000

Report type (0-2):

= area normalization
= internal standard
2 = external standard
Area real location factor (for fused peaks)
1

(0-100):

= dropping the perpendicular
100 = complete GLC-8 algorithm (see Appendix D),
IS TM/SCALE

Elution time of internal standard (1-4095 seconds).
Scale factor to which other components are scaled;
used for external standard (1-4095); 1 is normally
sufficient

RPKT, RRT, TBEG, TEND

Retention time of reference peak (1-4095 seconds).
Relative retention time of reference peak

(1-4095 = 0.001 to 4.095).
Beginning and ending of time window in which
reference peak will be found (1-4095 seconds).
F TM,

CODE, VAL

Time at which function is implemented
(0-4096 sec). Function code (see below).
Value applicable to function (see below).

NOTES
Time (TM) must be entered in an increasing sequence,

Code

entered last

Allowable
Value

Explanation

Terminate run and write analysis report

Null

Start peak search; monitor signal;
accumulate peaks

Null

Stop peak search but continue monitoring

Null

signals

B-2

Default

Value

Allowable
Value

Explanation

Code

Autobase threshold

Default

Value

1-255

seconds

0-12

Amplitude threshold

Slope threshold; shoulder sensitivity
= ignore shoulders

0-255

Time filter period; validates peaks;

1-15

anti-noise spike control
(value stated in 1/2 seconds)

4095

0-255

Peak termination time; time-after-crest

seconds

terminator

Null

Fix baseline

Area threshold factor

Optional relay output

0-15

0-7
(octal)

1-4095

Reset filter factor

Adjusted retention time of component
NAME (0-4095 seconds)

TM,NAME,TOL,RF,CWT

Component name (1-6 characters, the first must be
a letter)

Time tolerance; search window; +and - number in
seconds
Response factor (0-32767)
Calibration weight (0-32767)

B .2 .2

ANALYZE AND CALIBRATE
Explanation and Responses

Questions

ID,

RCYCL

Identification (name) of analysis
(1-16 characters, the first must be a letter)

Recycle for next sample (0 or 1):

= single analysis
1 = multiple analyses

NORM
EXSTD

For normalization only.
Total component weight (1-40959)
For external standard only.
10000 x actual component
Response
-5-

weight percent = comp

B-3

% reported

(1 -40959)

Questions

SAMP WT, STD WT

Explanation and Responses
For internal standard only
Total sample weight (1-40959),
Internal standard weight (1-40959)

B-4

APPENDIX C
ERROR MESSAGES

Error messages are composed of a three-character

and the next two characters are the error code.

The first character is an asterisk

In the following list, when the second error code

with the parameter number in error, i .e.,

character is shown as an n, the n is actually replaced

means the second parameter is not numeric.

code.

Error messages are printed immediately after you

line terminator, the colon.

Error Message

Meaning

*B3

Chromatograph to which method is assigned is busy

*Cn

Character string not present

*DM

Method deleted in modify since it is impossible to enter an
internal standard

method is deleted

*D0

Insufficient disk storage,

*D1

Insufficient memory to run analysis

*D2

Insufficient memory to accommodate new method

*I1

Internal standard not entered

*I2

Cannot modify function code zero in analysis method

*I3

Illegal

*M2

Method is missing

*Nn

Numeric response not present

*Pn

More then n parameters expected

*P0

Enter parameters

*S1

Statement not recognized

*S2

Sequence error, third parameter must be equal to or
than second parameter or zero

*T1

chromatograph/method pair

Component or function time not greater than last component
or function time

*T2

Insufficient memory to schedule the analysis

*U2

Method number is already entered in

*Vn

Value too large

*Zn

Zero is illegal value

mn METHOD BUSY

greater

method library

Method number mn is running an analysis

C-1

type the

APPENDIX D
ANALYSIS SEQUENCE

D.l

DURING THE ANALYSIS
During the analysis, GLC-8 accumulates and

calculates the chromatograph data as explained

below.

1 . 1

Peak Detection

When the system is actively searching for peaks, it maintains a trend

analysis not of the

filtered version of it, i .e. , the smoothed signal

digitalized chromatograph output but of a software

The smoothed signal is defined as:
SS new = (new unsmoothed signal) + (1-2

-FF
)

x SS old

where SS is smoothed signal and FF is filter factor.

A running estimate of what the baseline should be is maintained as a continuous
computed average of the current
Best estimate of baseline (BEB) is a mathematically
If the signal

this potential

(see Figure

variable.

baseline amplitude.

positively penetrates the amplitude threshold, the system tests the validity of

new peak while simultaneously integrating the potential peak as though it were valid

D-1).

The system freezes the potential new peak's start time/lieight vector at the sample

period just prior to the period in which the amplitude threshold was

accumulates the peak area.

For a defined time filter period (code 6) the signal

signal decreases during this period, the potential

monitored.

If the

peak is rejected and the system reverts to tracking

baseline, thus constituting the noise spike filter feature.
Is compared with

penetrated, and it temporarily

At the end of the filter time period, the area

the area threshold (code 9)

A = Amplitude threshold (code 4)
A'= Area threshold (code 9)
T

BEB = Best estimate of baseline

BEB

Rgure D-1

=Time filter threshold (code 6)

Peak Detection

D-1

If the area

does not exceed the area threshold, the potential

again reverts to tracking baseline (this feature discriminates

peak is rejected and the system

a true peak from baseline drift).

Peak termination is the Inverse of peak detection.

D.l .2

Shoulders
If the slope starts to decrease and if the

magnitude of the decrease is In excess of a specified

threshold value (see Figure D-2), the first inflection
point is

variable, called the slope threshold (code 5) .

established.

This threshold is a control

The slope threshold can be altered at any time by

implementing function code 5.
If the slope again

begins to rise,

if the

magnitude of the rise exceeds the slope threshold,

and if the time difference between the two inflections

exceeds the time filter period, the peak Integrated so far is designated a shoulder and terminated; a new peak
Is generated, effective from the second
inflection

However, if the elapsed time between the two Inflections does
period, the potential shoulder is rejected as being

not exceed the time filter

caused by a noise spike.

trailing shoulders.

Figure D-2

D-2

Shoulders

The reverse Is true for

. 1

Stora ge of Peak Parameters

Using the disk as a chained array, the following information
Start time

Start height

Crest time

Crest height

End time

End height

for each peak is stored:

Total Peak area
This can be envisioned as pictured below.

Inflection Point

Resolved peaks
area dow n to

Fused pecks

;

treated as 2 peaks

Figure D-3

D.2

Shoulders

;

Peak and Shoulder Detection

AFTER THE ANALYSIS
Upon completion of the chromatographic analysis, GLC-8

reconstructs the chromatogram

and performs analysis calculations as explained below.

D.2.1

Baseline Correction
This operation can be explained in five steps:

Start of the first peak and the end of the last

peak are called basepoints

2 .

A scan is made to establish basepoints as per the autobase time limit (code 3)

A scan is made to establish basepoints by fixing the baseline (code 8)

A scan is made to establish basepoints by peak termination time (code 7)

Starting from the first established basepoint , the

program successively calculates the
the next established basebasepoint and each subsequent valley until it encounters

slope between that
having the most negative (or least positive) slope is
point. The right-hand end (valley) of the line
repeated unti the end of the last peak is found
flagged as a basepoint . This double-step operation is
area
this baseline is subtracted from each peak
The basepoints are then connected and the area below
I

(see Figure D-4)

D-3

©
Numbers 1 through 5 correspond to the numbered steps in the
discussion above.
-represents the corrected baseline established in step 5

Figure D-4

D.2.2

above.

Baseline Correction

Area Reallocation

Upon completion of baseline correction, the chromatogram is again

processed for area re-

Area reallocation is the dividing of disputed peak areas when peaks are

allocation .

area is always relinquished by a smaller peak to those

fused.

adjacent peaks which are larger.

area of the smaller peak is that area which lies below a straight

Disputed

The allocatable

line between its start and end points.

The fraction of this allocatable area to be relinquished to a larger

neighbor is a function of the follow-

ing.

a .

The area allocation factor (AF) specified in the method.

The relative heights of the smaller and larger peaks (relative peak size).

c
The relative heights and positions of the peak start and end points a
degree of fusion '
(
amount of skew)
.

D-4

The function (described under c on the preceding page), is used to proportion the allocatable area

peak, and to

between the competing requirements of the two larger peaks on either side of the smaller
apply a weight factor for the relative position of a smaller peak on the tail of
If the area reallocation factor is zero,

a larger peak.

the area reallocation procedure is equivalent to the

technique of "dropping the perpendicular".

Peak Identification

D.2.3

After area reallocation, the chromatogram is compared with the method's
identify the individual peaks and to determine each peak weight or

volume fraction for analysis

calculations, or to update the component response factors in the method
is

component list to

during calibration.

A peak

peak whose crest time
identified with one of the listed components of a method, if it is the largest

tolerance zone of that comafter reference peak scaling (adjusted retention time) falls within a time

ponent

reference peak was found, the peak crest time is used for this comparison

If no

does not fall within the time tolerance zone of any component or is not

If a peak

the largest peak which falls

within the time tolerance zone of any component, it is declared an unknown.

The component time and

tolerance zone are listed in the method.

Peak identification is calculated internally using the following algorithm.
ERT

!-x ART. =CRT.

ART
r

where

= expected (adjusted) retention time of reference peak (compound table)

ERT

= actual retention time of reference peak (analysis report)

ART
r

ART.

= actual retention time of interested peak (analysis report)

CRT.

= calculated retention time of interested peak

Or, using the first peak in the analysis of Section 3.8, Figure 10:

^
304

07 _ oz
X 37 - 36

where the 36-second result (CRTj) is well within the ±10 second tolerance specified
table.

in the compound

Therefore, our first peak was properly identified.
If the calculated retention time of an interested peak is

outside the specified time tolerance,

the peak will not be properly identified, instead, it will be reported

as an unknown, as it might even

when the actual retention time (ART.) is within the specified tolerance.

D-5

For example,

if the

reference

peak had eluted ai 290 seconds (within Its specified tolerance) and our first peak at 41
its

seconds (within

specified tolerance), consider the following:

5^ X 41 - 43
where the 43-second result (CRT.) is outside the specified tolerance.

Should this happen, alter the

compound table.
Therefore, even when an interested peak is reported as being within the specified time

tolerance, the retention time of the reference peak determines whether that peak will be properly
identified

An additional convention applies such that if two peaks, the second being the larger, fall
within the tolerance zones of two components, the second peak is assigned the first component
first is

declared an unknown.

D.2.4

Peak Analysis

and the

Final analysis or calibration calculations are made using one of three analysis techniques:

normalization, internal standard, or external standard.

method.

The technique to be used is specified in the

On each identified peak, one of the following formulas applies:

Analysis

Calibration

Normal ization
.,,

Normalization

NORM

^RiAi

CW.
IS

100
i

CW.

Internal Standard

NORM

Internal Standard

WTIS

100000

100

SAMP

CW.
p
^i

_
~

IS
!_

CWT"
IS

External Standard

W
^i

= R
'^i

A
A,

External Standard

X
>«

10~^^ X
'0

^XTSD
CW. X

-pgog^
R.
r

D-6

-SF

10000

EXTSD

where
i

= Peak number

= Weight or volume fraction in percent

= Response factor of component matched to peak

= Peak

Internal standard peak

area

peak i in the
Stated weight or weight percent of component, matched to
calibration standard sample

A method-defined scale down factor

= Stated sample/internal standard weights; an internal standard for analysis

CW.
'

run.

D-7

INDEX

Component name (NAME), 2-10
Adjusted retention time (RPKT), 2-6, 2-10

Component weight, 2-10

Amplitude threshold function, 2-7, B-3
Analysis description, 1-4, D-1

DELETE Command, 2-16

ANALYZE Command, 2-12

Disk loading, A-2

ASSIGN Command, 2-2

DUMP command, 2-15, 3-2

Area factor (AF), 2-5

Dropping the perpendicular technique, 2-5, D-4

Area reallocation, D-4
E

Area threshold function, 2-7, B-3
Autobase threshold function, 2-7, B-3

ENTER Command, 2-3, B-1, -2, -3
Error messages, 1-10,

C-1

EX STD, 2-13, B-3
Background programs, 1-8
F

Baseline function, 2-9, B-3
Baseline correction,
Bootstrap loader,

D-3

A-1

Building a method, 2-3

Failsafe feature, A-3, -4
Filter factor (FF),

2-4, D-1

Flowchart, Loading and starting procedures, A-3

Adjusted retention time (RPKT), 2-6, 2-10

Flowchart, System operation, 3-9

Area factor (AF), 2-5
Filter factor (FF), 2-4, B-2
Instrument (INST), 2-3
Peak count (PK CT), 2-3

Foreground programs, 1-8

Relative retention time (RRT), 2-6

Report type (RTYP), 2-5, B-2

Sampling rate (SMPR), 2-4, B-2
Smoothed signal (SS), 2-4, D-1
Unknowns (UNK), 2-4, B-2

CALIBRATE Command, 2-14
Calibration peak, D-5

Code, function, 2-7, -8,-9, B-2, -3

F TM,

CODE, VAL, 2-6, -7, -8, -9, B-2

Functions, 2-7, -8, -9, B-2, -3

Amplitude threshold, 2-7, B-3
Area threshold, 2-9, B-3
Autobase threshold, 2-7, B-3
Baseline, 2-9, B-3
Optional relay output, 2-9, B-3
Peak search, 2-7
Peak termination, 2-8, B-3
Slope threshold, 2-8, B-3
Terminate run, 2-7, B-3
Time filter period, 2-8, B-3
Reset filter factor, 2-8, B-3

Commands, Monitor,

(See Monitor commands)

Hardware, 1-5, 1-8

INDEX (Cont)

I
ID, RCYCL, 2-13, B-3

Peak

INST, PK CT, 2-3, B-1

analysis,

Instrument number (INST), 2-3

calibration,

D-6
D-5

count (PK CT), 2-3
IS TM/SCALE,

2-5, B-2

detection, D-1
identification,

D-5

reference, 2-6

search function, 2-7

Loading and starting procedures, A-1

termination function, 2-8, B-3

Bootstrap loader, A-1, -2

Disk, A-2

Flowchart, A-3
Loading into core, A-2
Local operators console (LOC), 1-6, -7

Reference peak, 2-6
Relative retention time (RRT), 1-5, 2-6

Relay output, optional, 2-9

Messages, error, 1-10, C-1

Report type (RTYP), 2-5, B-2
examples.

Methods, examples, 3-1, -2, -3, 3-8

Response factor, 2-10

Modes of operation , 1-10

RPKT, RRT, TBEG, TEND, 2-6, B-2

MODIFY Command, 1-9, 2-2, 2-13, B-1

RTYP, AF, 2-5, B-2

Monitor commands

ANALYZE, 1-9, 2-12, 3-2, 3-8, B-1, B-3
ASSIGN, 1-9, 2-2, 3-1, B-1

SAMP WT, STD WT, B-4

CALIBRATE, 1-9, 2-2, 2-13, 3-6, B-1, B-3
DELETE, 1-10, 2-2, 2-16, B-1

Sample weight, B-4

DUMP, 1-10, 2-2, 2-15, 3-2, 3-6, B-1

Sampling rate (SMPR), 2-4, B-2

ENTER, 1-9, 2-1, -3, 3-1, B-1

Search-time zone, 2-6

MODIFY, 1-9, 2-2, 2-13, B-1
Shoulders,

D-2

Monitors/stem, 1-1
Sensitivity, 2-8, B-3

Slope threshold function, 2-8, B-3

NORM 2-13, B-3

Smoothed signal (SS), 2-4, D-1

Normalization Analysis 2-12

System
configuration, 1-5

O
Optional relay output function, 2-9, B-3

initialization, 1-8

Monitor, 1-1
operation, flowchart, 3-9

INDEX (Cont)

Software, 1-8

Background programs, 1-8
Foreground programs, 1-8

Summary of commands,
questions and responses, B-1, -2, -3

Technique, Dropping the perpendicular 2-5, D-4
Teletype console, 1-9

Terminate run function, 2-7
Threshold,

Amplitude, 2-7
Area, 2-9
Autobase, 2-7
Slope, 2-8
Time,
Adjusted retention, 2-6, 2-10
Relative retention, 1-5, 2-6

Search-time zone, 2-6
Tolerance, 2-10
Filter period function,

2-8, B-3

TM, NAME, TOL, RF, CWT, 2-10, B-3

y
UNK, FF, SMPR, 2-4, -5, B-2
Unknowns (UNK), 2-4, B-2

GLC-8 CHROMATOGRAPHERS GUIDE
DEC-CP-GAYB-D

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