vxEPA
United States
Environmental Protection
Agency
Environmental Monitoring and
Support Laboratory
Cincinnati OH 45268
Research and Development
EPA-600/S4-81 -064 May 1982
Project Summary
The Continuous Flow
Analyzer Automation System
Jonathan E. Kopke
This paper details the development
of a computer automation system for
continuous flow analyzers. The instru-
ments involved are commercially avail-
able Technicon AutoAnalyzers. The
computer system employed is a Data
General Nova 840 minicomputer with
an extended BASIC language which is
modified to allow for real-time data
acquisition in a multi-user, timeshar-
ing environment.
The automation system can collect,
and process data from up to three
detectors per user. An elaborate set of
original peak height determination and
timing synchronization algorithms is
incorporated into the system. The
system also provides for: (1) correction
for baseline drift; (2) calibration using
regression or interpolation; (3) plotting
of calibration curves; (4) determination
of concentrations; (5) quality control
assessments in real-time for spiked
samples, duplicate samples, laboratory
control standards, instrument check
standards, and reagent blanks; (6) com-
pensation for dilution; (7) reagent
blank subtraction; (8) remeasurement
of questionable samples; (9) printing
of progress and final reports; (10)
bidirectional communication with the
EPA national data base. Sample File
Control; (11) checking of the instru-
ment and interface hardware; and (12)
plotting of raw data. Most of these
features can be used in an
unattended mode.
This Project Summary was develop-
ed by EPA's Environmental Monitoring
and Support Laboratory. Cincinnati,
OH. to announce key findings of the
research project that is fully docu-
mented in a separate report of the
same title (see Project Report ordering
information at back).
Introduction
The history of this project can be
traced to 1974 when the Lawrence
Livermore Laboratory of the University
of California was first contracted by the
EPA to automate the continuous flow
analyzers manufactured under the trade
name "Technicon AutoAnalyzer." Much
pioneer work in laboratory automation
was done at Livermore, and a set of
automation programs written there for
the continuous flow analyzer has been
in use in EPA laboratories for several
years.
Recent advances in quality control
procedures and laboratory data basing,
however, mandated that the automation
system be revamped for the 1980s.
Furthermore, as the possibility of cre-
ating a new system was explored, it was
decided that more general peak height
determination and timing synchroniza-
tion algorithms should also be develop-
ed.
The Continuous Flow Analyzer (CFA)
automation system consists of 21 major
computer programs. It is written in Data
General Extended BASIC, Revision 4.3,
as enhanced for real-time data acqui-
sition by Lawrence Livermore Labora-
tory. It runs in a Data General Nova 840
minicomputer, under the Real-Time Disk
Operating System (RDOS), Revision 6.2.
The system is as self-explanatory and
mistake-proof as possible. To protect its
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own integrity, the system makes it im-
possible for any user to alter any pro-
gram or to even reach the BASIC
language command level.
This system is part of a large labora-
tory automation effort. There are parallel
systems using consistent procedures
and algorithms for flame and furnace
atomic absorption units, ultraviolet/
visible light spectrometers, and gas chro-
matographs.
Features of the
Automation System
Raw Data Acquisition
The system acquires raw data from
the instruments in real-time through
specially designed interface boxes incor-
porating differential amplifiers. The
analogue signals are digitized and col-
lected by the automation system during
"data acquisition windows," as shown
in Figure 1.
Peak Height Determination
An elaborate peak height determina-
tion algorithm essentially locates the
highest level position on each peak and
provides a smoothed reading from that
position. The heights of shoulder peaks
are determined by a second algorithm
which calculates the smoothed reading
at the expected position of the most
valid reading. Abnormally contorted
peaks are rejected, and the samples
which caused them are automatically
assigned to remeasurement positions.
Synchronization with the
Automatic Sampler
The system automatically establishes
synchronization with any fixed-interval
automatic sampler by detecting a "tim-
ing set standard" at the beginning of a
batch of samples. It maintains timing
synchronization by automatically length-
ening or shortening the dead time
between data acquisition windows
when necessary to keep the peaks in the
center third of the windows.
Correction for Baseline Drift
The system continually interpolates a
baseline between the heights of periodic
blanks and subtracts that baseline from
each peak height to compensate for
baseline drift.
Calibration
Calibration can be accomplished
using first, second, or third degree
BNflLYTE: 6219001
R-fi-U D-fl-T-fl P-L-O-T
BRTE: 05/02.'80
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004 005 006 007 008 009 010
UHEEL POSITION
OH 01£ 013
Figure 1. Typical raw data plot.
regression or linear interpolation. The
analyst has the options of deleting out-
lying calibration standards and changing
the type of curvefitting. Calibration curve
plots are provided, as shown in Figure 2.
Quality Control Assessments
Quality control assessments are pro-
vided seconds after the related samples
pass through the instrument. Spiked
C-fl-L-
BNBLYTE: 6210001
DE&REE: 1 FITTING ERROR:
I-B-R-fi-T-I-O-N R-E-P-0-R-T
DflTE OF CfiLIBRflTION: 05/62x30
0.30\ FORCED ORIGIN FITTING ERROR: l.ll'-s
CONC = -1.45E+08 -H.04E+00 *ECPH
100
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TCONC CONC
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60.000 59.852
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36.00 45.ee 54.ee 63.ee 72.ee si.e© 90.00 99.00
CONCENTRBTION IN ME/L
Figure 2. Typical calibration curve plot.
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samples, duplicate samples, laboratory
control standards, and reagent blanks
are all automatically evaluated against
limits provided by the Sample File
Control System (as described below) or
by the analyst. Instrument check stand-
ards are automatically assessed against
limits provided by the analyst.
Compensation for Dilution
Dilution factors are taken into account
so that the system reports true concen-
trations. Furthermore, for samples
which are offscale, the system automat-
ically prescribes an appropriate dilution
factor and instructs the analyst where to
place the diluted samples in the sample
wheel so that they can be remeasured.
Reagent Blank Subtraction
The peak heights of reagent blanks
can be subtracted from any or all of the
other samples in a batch at the discretion
of the analyst.
Reports
Sample wheel template reports, qual-
ity control limit reports, sample wheel
pattern reports, progress reports, cali-
bration reports, reagent blank reports,
final reports, subtracted results reports,
and raw data reports are all available. A
typical final report is shown in Figure 3.
Subtraction for Calculated
Results
The system can calculate subtracted
results, as in the case of the "nitrate-
nitrite minus nitrite" method for meas-
uring nitrate.
Sample File Control Interaction
This automation system can commu-
nicate bidirectionally with the EPA's
national data base. Sample File Control.
It can automatically accept from the
Sample File Control computer a "run
file," which is a list of the samples
which need to be measured, together
with the quality control limits currently
in effect for each unique combination of
parameter, method, preparation proce-
dure, and environmental source.
The system can also send back to the
Sample File Control computer a "run
results file" containing the measured
concentration of the samples and related
data.
F-I-N-A-L R-E-P-0-R-T
DATE: 05/02/80
COMMENTS: SIMULATED THREE-ANALYTE RUN
NAME OF RUN FILE: 6200001. RF
MODE OF OPERATION: ATTENDED
TINE BETWEEN PEAKS: 30 SECONDS
ADDITIONAL DILUTION FACTOR FOR OFFSCALE SAMPLES: 4
DEFAULT CONCENTRATION UNIT:
A/D CHANNEL NUMBER :
SET STANDARD THRESHOLD HEIGHT:
DATA ACQUISITION UINDOU WIDTH.
STANDARD DEVIATION DEFINING LEVELNESS:
DETECTION LIMIT:
OFFSCALE CONCENTRATION:
ALLOWABLE ERROR FOR CHECK STANDARDS:
TYPE OF FIT:
CALIBRATION FITTING ERROR:
FORCED ORIGIN FITTING ERROR:
CALIBRATION EQUATIONS:
6210001: CONC = -1.45E+00 +1.04E+00
6220001: CONC = -1.13E+00 +S.37E-01
6230001: INTERPOLATION
WHEEL SAMPLE DILUTION
POSITION TYPE FACTOR
001 (1/001) SET STANDARD PH:
002 (1/002) SET STANDARD PH:
003 (1/003) SET STANDARD PH:
004 (1/004) BLANK PH:
005 (1/005) BLANK PH:
006 (1/006) CAL STANDARD BCPH:
TCONC:
007 (1/007) CAL STANDARD BCPH:
TCONC:
008 (1/008) CAL STANDARD BCPH:
TCONC:
009 (1/009) BLANK PH:
010 (1/010) BLANK PH.
Oil (1/011) ID: 00000001 1.00 BCPH:
CONC:
012 (1/012) ID: 00000002 1.00 BCPH:
CONC:
013 (1/013) SPIKE OF 012 1.00 BCPH:
LSF:
LSA:
RECV:
QC:
014 (1/014) DUPE OF 012 1.00 BCPH:
LD2:
RNG:
015 (1/015) CONTROL STND BCPH I
LCM:
LCT:
RECV:
QC:
016 (1/016) CHECK OF 007 BCPH:
017 (1/017) REAGENT BLNK BCPH'
CONC:
QC: ,
nift si smn\ m A&II/ nu .^
6210001
VALUES
MGio
50
20
0.60
20.000
90.000
10.002
1
0.302
1.112
*BCPH
tBCPH -1
6210001
RESULTS
100.013
75.092
74.700
1.671
1.572
30.302
30 . 000
58.929
60.000
87.983
90.000
0.235
0.158
59.881
60.842
fl:JB
69.468
70.815
30.000
99.672
OK
42.244
42.496
1.583
OK
44.693
45.044
45.000
100.102
OK
60.015
101.842,
O.i^^
X^
6220001
VALUES
MG/L
11
50
20
0.60
12.000
55.000
10.002
2
0.002
1.102
6230001
VALUES
10
50
20
0.60
18.000
95.000
10.002
0
0.002
1.122
41E-04 *BCPHA2
6220001
RESULTS
CBD
75.104
74.678
1.689
1.614
30.292
15.000
58.907
30.000
87.973
45.000
0.231
0.171
SEE 030
40.726
20.496
69.440
35.463
15.000
99.782
OK
42.203
21.272
0.776
OK
44.694
22.578
22.500
100.352
sr^
^
6230001
RESULTS
99.997
75.136
74.703
1.720
1.644
30.304
20.000
58.924
40.000
87.963
60.000
0 17^
SEE 030
40.724
27.282
69.444
47.245
20.000
99.8Z5!
OK
42.293
28.378
1.096
OK
44.794
30.126
30.000
^121 1
Figure 3. Typical final report.
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Instrument and Interface Check
The analyst can easily perform a test
of the instrument and interface elec-
tronics without risking actual samples.
Most of the features of this automa-
tion system can be used in an unat-
tended mode. Thus, a single analyst can
operate several instruments simulta-
neously, or even leave instruments
running during the night. The system is
currently operating reliably in one EPA
laboratory, and it is anticipated that it
will soon be installed in several more.
Jonathan £. Kopke is with the University of Cincinnati Computer Center,
Cincinnati, OH 45221.
John M. Teuschltr is the EPA Project Officer (see below).
The complete report, entitled "The Continuous Flow Analyzer Automation
System," consists of three volumes, as follows:
"Parti. Functional Specifications," (Order No. PB 82-191 081; Cost: $7.50)
"Partlf. User's Guide,"(Order No. PB82-199 951; Cost: $9.00)
"Part III. Program Documentation," (Order No. PB 82-199 969; Cost:
$19.50)
the above reports will be available only from: (costs subject to change}
National Technical Information Service
5285 Port Royal Road
Springfield, MA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Environmental Monitoring and Support Laboratory
U.S. Environmental Protection Agency
Cincinnati, OH 45268
•ft US GOVERNMENT PRINTING OFFICE, 1982 — 569-017/0729
United States
Environmental Protection
Agency
Center for Environmental Research
Information .
Cincinnati OH 45268
Postage and
Fees Paid
Environmental
Protection
Agency
EPA 335
Official Business
Penalty for Private Use $300
PS 00003?9
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