yyEPA
           United States
           Environmental Protection
           Agency
            Environmental Monitoring and
            Support Laboratory
            Cincinnati OH 45268
EPA-600/4-80-025
April 1980
           Research and Development
Performance
Tests for the
Evaluation of
Computerized Gas
Chromatography/
Mass Spectrometry
Equipment and
Laboratories

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                RESEARCH REPORTING SERIES

Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been groyped into nine series. These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology.  Eliminatipn  of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The nine series are:    .         I

      1,  Environmental  Health Effects Research
      2.  Environmental  Protection Technology
      3.  Ecological Research  i
      4.  Environmental  Monitoring
      5.  Socioeconomic Environmental Studies
      6.  Scientific and Technical  Assessment Reports (STAR)
      7.  Interagency  Energy-Environment Research and Development
      8.  "Special" Reports
      9,  Miscellaneous Reports

This report has been assigned tolthe ENVIRONMENTAL MONITORING series.
This series describes research conducted to develop new or improved methods
and  instrumentation for the identification and quantification of environmental
pollutants at the lowest conceivably significant concentrations. It also includes
studies to determine the ambient concentrations of pollutants in the environment
and/or the variance of pollutants ajs a function of time or meteorological factors.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 122161.

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                                              EPA-600/4-80-025
                                              April  1980
     PERFORMANCE TESTS FOR THE EVALUATION
               OF COMPUTERIZED
     GAS CHROMATOGRAPHY/MASS SPECTROMETRY
          EQUIPMENT AND LABORATORIES
                       by

               William L. Budde
                     and
            James W. Eichelberger
    . Physical and Chemical Methods Branch
Environmental Monitoring and Support Laboratory
            Cincinnati, Ohio 45268
ENVIRONMENTAL MONITORING AND SUPPORT LABORATORY
       OFFICE OF RESEARCH AND DEVELOPMENT
      U.S. ENVIRONMENTAL PROTECTION AGENCY
            CINCINNATI, OHIO 45268

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                                  DISCLAIMER
    This report has been reviewed by the Environmental Monitoring and
Support Laboratory, U.S. Environmental Protection Agency, and  approved for
publication.  Mention of trade names or commercial products does not
constitute endorsement or recommendation for use.

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                                   FOREWORD
    Environmental measurements are required to determine the quality of
ambient waters and the character of waste effluents.  The Environmental
Monitoring and Support Laboratory - Cincinnati, conducts research to:

    • Develop and evaluate methods to measure the presence and concentra-
      tion of physical, chemical, and radiological pollutants in water,'
      wastewater, bottom sediments, and solid waste.

    • Investigate methods for the concentration, recovery, and identifica-
      tion of viruses, bacteria and other microbiological organisms in
      water; and, to determine the responses of aquatic organisms to water
      quality.

    • Develop and operate an Agency-wide quality assurance program to assure
      standardization and quality control of systems for monitoring water
      and wastewater.

    • Develop and operate a computerized system for instrument automation
      leading to improved data collection, analysis, and quality control.

    This report was developed by the Advanced Instrumentation Section of the
Environmental Monitoring and Support Laboratory.  It describes a series of
general purpose tests to evaluate the performance of computerized gas
chromatography-mass spectrometry (GC/MS) systems.  Some of the tests go
beyond equipment performance and may be used to evaluate the performance of
laboratories using GC/MS for organics analysis.  The report will be useful
to the many Federal, State, local government, and private laboratories that
are planning to employ this powerful analytical tool.
                                     Dwight G. Ballinger
                                     Director
                                     Environmental Monitoring and Support
                                     Laboratory - Cincinnati

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                                   ABSTRACT
    A series of ten general purpose tests are described which are used to
evaluate the performance of computerized gas chromatography-mass
spectrometry systems.  All of the tests use the continuous, repetitive
measurement of spectra method of data acquisition, and no selected ion
monitoring tests are included.  Evaluation criteria are given with each
performance test.  Some of the tests go beyond equipment performance, and
may be used to evaluate the performance of laboratories using GS/MS for
organics analysis.
                                    iv

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                                   CONTENTS
Foreword	.. .iii
Abstract	iv
Figures	V1
Tables	vi
Acknowl edgment	'	,	v i i

    1.  Introducti on	1

    2.  Summary of Tests	3

    3.  Experimental Procedures	5

         Test I    Spectrum Validation...	5
         Test II   System Stability	8
         Test III  Instrument Detection Limit	8
         Test IV   Saturation Recovery.	11.
         Test V    Precision....	12
         Test VI   Library Search	16
         Test VII  Quantitative Analysis .with Liquid-Liquid Extraction	17
         Test VIII Quantitative Analysis with Inert Gas Purge and Trap	19
         Test IX   Qualitative Analysis with Real Samples	27
         Test X    Solid Probe Inlet System	.		30

  ^ 4.   References	32
                                      v.

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                                   FIGURES
Number
Page
  1      Control chart for nitrobenzene in reagent water	21
  2      Control chart 'for pyrene in reagent water	22

                                    TABLES
Number                                                                 Page
  1      Suggested GC Columns and Conditions	.	  7
  2      Decafluorotriphenylphosphine Key Ions and Ion Abundance	  7
         Criteria
  3      Ions Over 3% Relative Abundance Observed in the 70 ev Mass
         Spectrum of DFTPP	.	 10
  4      Common Background Ions in GC/MS Systems	 11
  5      Precision Statistics for Ten Priority Pollutants Plus
         Octadecane	 13
                                 i
  6      Precision Statistics Using an Internal Standard	 15
  7      £-Bromofluorobenzene Key Ions and Ion Abundance Criteria	 16
  8      Precision and Accuracy Data for Liquid-Liquid Extraction
         with GC/MS and an External Standard	 20
  9      Method Efficiencies for Some Priority Pollutants Plus
         £-Bromof 1 uorobenzene	 25
 10      Precision and Accuracy Data for the Purge and Trap Analysis
         with GC/MS and an External Standard	 26
 11      Precision and Accuracy Data for the Purge and Trap Analysis
         with GC/MS and the Internal Standard jD-Bromofluorobenzene	 28
 12      Precision and Accuracy Data for the Purge and Trap Analysis
         with GC/MS and the Internal Standard Dibromochloromethane	 29
                                     VI

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                                ACKNOWLEDGMENT
    The authors wish to acknowledge the careful  and  competent  technical
assistance of William Middleton, Jr., who has performed  all  of the  GC/MS
tests described in this report at  least once, and  several  of them hundreds
of times.

    A number of Environmental Protection Agency  personnel  reviewed  the first
draft of this report, and many provided written  comments which substantially
assisted the authors in the preparation of this  document.  Our deep
appreciation is due to all of the  following:
William Andrade
Region 1
Surveillance and Analysis Division
Lexington, MA  02173

Thomas A. Beliar
Environmental Monitoring and
Support Laboratory
Cincinnati, OH  45268

Robert L. Booth, Deputy Director
Environmental Monitoring and
Support Laboratory
Cincinnati, OH  45268

Aubry E. Dupuy, Jr.
Pesticides Monitoring Laboratory
Bay Saint Louis, MS  39520
Robert D. Kleopfer
Region 7
Surveillance and Analysis Division
Kansas City, KS  66115

John Logsdon
National Enforcement
Investigation Center
Denver, CO  80225
Dwight G. Ballinger, Director
Environmental Monitoring and
Support Laboratory
Cincinnati, OH  45268

Joseph N. Blazevich
Region 10
Surveillance and Analysis Division
Manchester, WA  98353

Herbert J. Brass
Division of Technical Support
Cincinnati, OH  45268  ,
Denis Foerst
Environmental Monitoring and
Support Laboratory
Cincinnati, OH  45268

John Kopp
Environmental Monitoring and
Support Laboratory
Cincinnati, OH  45268

E. William Loy, Jr.
Region 4
Surveillance and Analysis Division
Athens, GA 30601
                                     vn

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John M. McGuire
Environmental Research Laboratory
Athens, 6A  30601

Aaron A. Rosen
Cincinnati Water Works
Cincinnati, OH  45228
D. C. Shew
R. S. Kerr Environmental
Research Laboratory
Ada, OK  74820

Alan Stevens
Municipal Environmental
Research Laboratory
Cincinnati, OH  45268
Curt Norwood
Environmental Research Laboratory
Narragansett, RI  02882

Dennis R. Seeger
Municipal Environmental
Research Laboratory
Cincinnati, OH  45268

Clois Slocum
Municipal Environmental Research
Laboratory
Cincinnati, OH  45268

Emilio Sturino
Region 5
Surveillance and Analysis Division
Chicago, IL  60606
    The second draft was reviewed by the following, and we are similarly
grateful for their very helpful written comments.
Joan T. Bursey
Research Triangle Institute
Research Triangle Park, NC  27709

Leonard F. Herzog
Nuclide Corporation
State College, PA  16801

Russell L. McAvoy
U.S. Geological Service
Denver, CO  80225

M. W. Siege!
Extranuclear Laboratories, Inc.
Pittsburgh, PA.  15238

Jim Stauffer
Arthur D. Little, Inc.
Cambridge, MA  02140
Kathy Thrun
Arthur D. Little, Inc.
Cambridge, MA  02140

John A. Winter
Environmental Monitoring
and Support Laboratory
Cincinnati, OH  45268
Edward M. Chait
E.I. DuPont DeNemours and Company
Wilmington, DE  19898

Philip L. Levins
Arthur D. Little, Inc.
Cambridge, MA  02140

David J. Munch
EPA Office of Drinking Water
Cincinnati, OH  45268

David E. Smith
Finnigan Corporation
Sunnyvale, CA  94086

Paul A. Taylor
California Analytical Laboratories,
Incorporated
Sacramento, CA  95814

Kenneth B. Tomer
Research Triangle Institute
Research Triangle Park, NC  27709
                                     vm

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                                   SECTION  1

                                  INTRODUCTION
    This report gives  a  series of performance  tests  to  evaluate computerized
gas chromatography - mass spectrometry  (GC/MS)  systems.   These tests were
designed for general use, and are applicable to all  types of GC/MS systems.
All of the tests use the continuous, repetitive measurement  of spectra
method of data acquisition, and no  selected  ion monitoring tests are
included.  Except for  the spectrum  validation  test  (Test  I),  these
performance tests are  not intended  for  routine  application in a quality
assurance program.  Test I is a required daily  quality  control test for
GC/MS systems in routine use for measurements  of organic  compounds in
environmental samples.  The other performance  tests  are intended for use in
the evaluation of new  GC/MS systems before purchase,  or after the completion
of the manufacturer's  installation. These tests are  also  useful  to evaluate
GC/MS performance after  a long period of downtime for extensive maintenance
or repair, after a long period of equipment neglect  or  non-use,  or as
general training experiments for GC/MS  operators.  Several of the tests go
beyond equipment performance and may be used to evaluate  the  performance of
laboratories using GC/MS for organics analysis.

    The performance tests described in  this report are  more  rigorous and
extensive than the typical manufacturer's installation  tests.   Indeed,  this
was intended, and the  emphasis of the tests  is  on an  evaluation  of the  total
operating system in a  rigorous way  using experiments  that closely resemble
real, day-to-day operating situations.  The performance tests should be
conducted in the order given, but several are  optional  or depend on the
availability of certain accessories, e.g., the  solid  probe inlet test.

    All the tests described in this report require an operator,  and some
depend heavily on the  skills of laboratory personnel.   Therefore,  the
results of some tests  may be limited by the skills available  in  the
laboratory.  An experienced, two-person team consisting of a  professional
scientist and a technician will require approximately three  weeks to
complete the equipment tests assuming there are no major  hardware or
software problems.  Inexperienced teams or individuals  may require anywhere
from six weeks to one year to complete  all the  tests, especially if major
hardware or software problems develop.  In these tests, the  operator and
other laboratory personnel are a crucial part of the  total operating system.

    The examples given in this report reference packed  column gas chromatog-
raphy, but the tests described are equally applicable to  open tubular GC/MS

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systems.  With open tubular  (capillary)  systems  some  minor  adjustments  in
operating conditions may be  necessary.

    For all the tests  it is  assumed  that the  manufacturer has  provided
acceptable documentation of  users  instructions for  the  operation  and
maintenance of the GC/MS system.   At the very minimum this  must include
clearly written descriptions of  all  operating and test  functions,  clear
descriptions of all commands used  in the operation  of the data system,
examples of all commands,  and  intelligible  documentation of error messages.
Examples of all outputs must be  included as well as error recovery
procedures.  There must be a narrative description  of all data system files,
and the narrative should describe  the exact nature  of the algorithm used for
all the significant mass spectrometric processes.   The  maintenance manuals
must include a complete set  of hardware  engineering drawings,  and
maintenance must be described  in terms of block  diagrams, logic diagrams,
flow charts, circuit descriptions, and parts  lists.

    It is also assumed that  the  laboratory  has provided the GC/MS facility
with an appropriate environment  including air conditioning  and other
utilities as required, trained management and operating personnels needed
supplies, essential support  equipment, and  a  reasonable amount of working
space which allows access  at the sides and  rear  of  the  system  for
maintenance.

    Finally, a system  logbook  must jbe maintained throughout the evaluation
period.  This must include an  entry  for  every working day noting  the status
of the system.  This entry must  be imade  even  if  the system  is  not used  on
that day, and signed by the  responsible  person.  The  logbook must include a
complete record of the number  of gas chromatographic  injections per day, the
number of solid probe samples, all chromatographic  column changes, all
maintenance procedures, all  requirements for  service  from the  manufacturer,
and each entry must be signed  and  dated.  This information  must be
summarized in the performance  evaluation report, and  the mean  numbers of gas
chromatographic injections and solid probe  samples  before ion  source
maintenance (cleaning) must  be reported.

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                     \
I.
II.

Ill,
IV.
V.
VI.
VII,
                             SECTION 2

                   &JMMARY OF PERFORMANCE TESTS

                      V
Spectrum Validation Test* ~ Uses decafluorotriphenyl  phosphine (DFTPP)
to determine whether the'.system gives a 70 ev electron ionization
fragmentation pattern  sinn lar to that found in the historical mass
spectrometry data base,  and-the required mass resolution and natural
abundance  isotope patterns. \The spectrum of DFTPP must meet the
criteria given  in Table  2.    \
System Stability Test - Uses DFT»9P to test moderate term (20-28 hours)
system stability.  The criteria gSJven in Test I must be met.
 Instrument Detection Limit Test - Ustfs DFTPP to measure the full  and
 valid spectrum detection  limit at a defined and tolerable chemical
 noise level.  At a signal/noise = 5, t^e required instrument detection
 limits are at least 50 nanograms for systems used in the analysis of
 industrial or municipal wastes, and at  le^st 30 nanograms for systems
 used in the, analysis for  ambient or drinking water.

 Saturation Recovery Test  - Uses DFTPP and ^-bYomobiphenyl to simulate
 a frequently encountered  situation with  real  samples.   The spectrum of
 DFTPP, measured within two minutes after the  election of a 250 fold
 excess of £-bromobiphenyl, must not contain significant contributions
 from the ions attributable to £-bromobiphenyl.    \

 Precision Test - Uses a variety of typical environmental  pollutants to
 determine precision from  filling a syringe to peak integration.   The
 mean relative standard deviation for the compounds used,in the test
 which elute as narrow peaks must be 7% or less  using either peak  areas
 in arbitrary units or ratios of peak areas.  For  broad  peaks the  mean
 relative standard deviation must be 13%  or less.

.Library Search Test - Uses data from Test V to  evaluate the  speed and
 completeness of the minicomputer library search algorithm.   Th«? mean
 search time, including background subtraction,  must be  one minute or
 less, and all test compounds must be identified as most probable
 except isomers with very  similar spectra should not be  counted as
 incorrect.

 Quantitative Analysis with Liquid-Liquid Extraction - Uses  a variety
 of environmental pollutants to measure quantitative accuracy and
                                       3

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      precision of the total analytical method.  The grand average of the
      percentages of the true values observed must be in the 68-132% range
      with a mean relative standard deviation of 38% or less using either
      internal or external standards.  This test also evaluates laboratory
      performance.

VIII. Quantitative Analysis with Inert Gas Purge and Trap - Uses a variety
      of compounds to measure quantitative accuracy and precision of the
      total analytical method.  The grand average of the method efficiencies
      must be 70% or more, and all; compounds must exceed 30% efficiency.
      The spectrum of _p_-bromofluor|o- benzene must meet the criteria given in
      Table 7.  The grand average |of the percentages of the true values
      observed must be in the range of 90-110% with a mean relative standard
      deviation of 19% or less using either internal or external standards.
                                  i
IX.   Qualitative Analysis with Real Samples - Uses a real sample to
      evaluate the ability of the [system to deal with real sample matrix
      effects and interferences.  'All compounds must be correctly identified
      except isomers with nearly identical mass spectra should not be
      counted as incorrect.  This !test also evaluates laboratory performance.

X.    Solid Probe Inlet System Test (Optional) - Uses cholesterol  to
      evaluate the spectrum validijty achievable with a solid probe inlet
      system.  The spectrum of cholesterol must meet the criteria given in
      step three of the test.

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                                  SECTION 3

                           EXPERIMENTAL PROCEDURES
I.  Spectrum Validation Test

      Correct identifications of organic pollutants from gas chromatography
mass spectrometry (GC/MS) data require valid mass spectra of the compounds
detected.  This is prerequisite to the interpretation of the spectra, i.e.,
either an empirical search for a match within a collection of authentic
spectra or an analysis from the principles of organic ion fragmentation.  A
properly operating and well tuned GC/MS :is required to obtain valid mass
spectra.

      The purpose of this test is to make a quick check - about 15 minutes -
of the performance of the total operating system of a computerized GC/MS.
Thus with a minimum expenditure of time, an operator can be reasonably sure
that the GC column, the enrichment device, the ion source, the ion separa-
ting device, the ion detection device, the signal amplifying circuits, the
analog to digital converter, the data reduction system, and the data output
system are all functioning properly.

      An unsuccessful test requires, of course, the examination of the
individual subsystems and correction of the faulty component.  Environmental
data acquired after a successful systems check are, in a real sense, vali-
dated and of far more value than unvalidated data..  Environmental data
acquired after an unsuccessful test may be worthless and may cause erroneous
identifications.

      It is recommended that the test be applied at the beginning of a work
day on which the system will be used and also anytime there is a suspicion
of a malfunction.  A mass spectrometer which meets the criteria of this test
will, in general, generate mass spectra pf organic compounds which are very
similar, if not identical, to spectra in collections and textbooks which
have been developed over the years with other types of spectrometers.  If
the performance criteria of this test cannot be met by the user, the system
is unacceptable for general purpose environmental measurements.

Procedure:

      1.  Make up a stock solution of decafluorotriphenylphosphine (DFTPP)
          at one milligram per milliliter (1000 ppm) concentration in
          acetone (or a hydrocarbon .solvent).  The reference compound used
          in this test is available from PCR, Inc., P. 0. Box 1778,

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     Gainesville,  Florida,  32602  and may be named  bis(perfluorophenyl)
     phenylphosphine.   This stock solution  was  shown  to  be  97+%  stable
     after  six  months  and  indications are that  it  will remain  usable
     for  several years.  Dilute an aliquot  of the  stock  solution to 10
     micrograms per  milliliter  (10 ppm)  in  acetone.   The very  small
     quantity of material  present in very dilute solutions  is  subject
     to depreciation due to adsorption on the walls of the  glass
     container, reaction with trace impurities  in  acetone,  etc.
     Therefore, this solution will  be usable only  in  the short term,
     perhaps  one week.

2.   Select a GC column for the tests.   Any column that  elutes DFTPP in
     a reasonable  time may  be used,  and  several suggested columns are
     listed in  Table 1.  Parameters  should  be adjusted to permit at
     least  four mass scans  during elution of the DFTPP.  This  will
     permit selection of a  spectrum  that is reasonably free of
     abundance  distortions  due to rapidly changing sample pressure.

3.   Set  the  preamplifier to a suitable  sensitivity and  set the
     baseline threshold (zero instrument).  Mass scale calibration is
     optional depending on  the stability of the system — see  the last
     paragraph  of  this test.

4.   Prepare  for data acquisition with the  following  variables:
8.
9.
          Mass Range:
          Scan Time:
          Electron Energy:
          Electron Multiplier:
                             40-450 amu
                             approximately 2 to 5 seconds
                             70 ev
                             Not to exceed that recommended by the
                             supplier for the age of the device.
5.  Inject with a syringe 50 inanograms (five micro!iters) of the
    dilute standard into the GC column.  Make appropriate concentra-
    tion adjustments if an open tubular column is being used.

6.  After the acetone elutes from the column and is pumped or diverted
    from the system, turn on the ionizer and start scanning.

7.  Terminate the run after the DFTPP elutes, and plot the total ion
    current profile.
Select a spectrum number on the front side of the GC peak as near
the apex as possible, select a background spectrum number
immediately preceding the peak, and display the background
subtracted spectrum.  Some data systems permit spectrum averaging
to minimize variations in ion abundance due to rapidly changing
sample pressure.  This option is acceptable, and may be required
for narrow peaks from open tubular columns.

The mass spectrum can be output in various ways including a plot
of the full spectrum on the plotter or cathode ray tube or a print
of the full spectrum on a printer or cathode ray tube.

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                TABLE 1.  SUGGESTED GC COLUMNS AND CONDITIONS
Dimension (Type)   Packing
2m x 2 mm ID
   (Glass)
2m x 2 mm ID
   (Glass)

2m x 2 mm ID
2m x 2 mm ID
   (Glass)

30m x .25mm ID
   (Glass)
1.95% QF-1 plus
1.5% OV-17 on
80/100 mesh Gas-Chrqm Q

3% OV-1 on 80/100
mesh Chromosorb W

5% OV-17 on 80/100
mesh Chromosorb W

1% SP2250 on 100/120
mesh Supelcoport

Wall coated SP 2100
 Flow Rate

 30 ml/min



 30 ml/min


 30 ml/min


 30 ml/min


2-5 ml/min
  220
  220
  170
          R. Time

          4 min
5 min
5 min
5 min
40,240   10 min
The spectrum obtained on the test system must meet the criteria given for
the key ions in Table 2 (1).

      If the relative abundances are not within the limits specified, the
appropriate adjustments must be made, i.e., resolution, source potentials,
calibration of the mass scale, source magnet position, etc.  The manufac-
turer may need to be consulted for assistance in this adjustment.  Repeat
this test until satisfactory results are obtained.  If computer controlled
tuning is used but manual adjustments are required to meet these criteria,
this should be noted in the evaluation.report.
  TABLE 2. DECAFLUOROTRIPHENYLPHOSPHINE KEY IONS AND ION ABUNDANCE CRITERIA.
           Mass

            51
            68
            70
           127
           197
           198
           199
           275
           365
           441
           442
           443
      Ion Abundance Criteria

      30-60% of Mass 198
      Less than 2% of Mass 69
      Less than 2% of Mass 69
      40-60% of Mass 198
      Less than 1% of Mass 198
      Base Peak, 100% Relative Abundance
      5-9% of Mass 198
      10-30% of Mass 198
      At least 1% of Mass 198
      Present, but less than Mass 443
      Greater than 40% of Mass 198
      17-23% of Mass 442

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II.  System Stability Test

    The purpose of this test is to evaluate moderate term system stability.
Repeat the test described in Section I after 20-28 hours.  Do not make any
adjustments or recalioration of the isystem between tests except routine
overnight procedures.  The abundance criteria in Table 2 must be met.  If
these criteria are not met, the system is too unstable for routine use and
must be repaired.

III.  Instrument Detection Limit Test

    This test is to determine the smallest quantity of standard test
material that can be injected into the GC/MS system that gives an acceptable
spectrum meeting the criteria in Table 2, but has a sufficiently low level
of background signals to allow correct interpretation of that spectrum if
the sample was an unknown.  Background signals are defined as mainly
chemical noise that is not subtracted effectively by the background
correction program.  A spectrum of a test compound contaminated with
background signals to the extent of about 10% or more of its total ion
abundance  is considered to be difficult to interpret correctly.  It may be
possible to find a target compund's Ispectrum in such a situation, but this
does not constitute an interpretation of an unknown spectrum as used here.
There is some variability in the 10% criteria because background distributed
among a large number of small ions may be acceptable, but a distribution
among a few large ions will be unacceptable.  Therefore, a signal to
chemical noise ratio based on a selection of six ions is used to evaluate
the detection limit.  This also allows a relatively simple calculation of
the ratio.

    In  a GC/MS system there are a number of potential sources of background
signals  (chemical noise)  including septum bleed, stationary phase bleed,
vacuum  system background from various physical components, and  ion source
contamination.   Furthermore, all signals are dependent on GC column
efficiency, enrichment device efficiency, vacuum system  efficiency,  lomza-
tion efficiency,  ion transmission efficiency,  and detector gain.  Therefore,
this test  is  highly  sensitive to the  specific  system configuration (specific
GC column, etc.)  and the  current condition  of  that  system, e.g., condition
of the  GC  column, extent  of contamination  in the  ion source, extent  of
contamination  of the quadrupole rods  if  a quadrupole instrument,  and
condition  of  the electron  multiplier.  The  state of the  system  should  be
documented as  part  of  the records  of  the instrument detection  limit  test.

Procedure:

     1.  Make four dilutions of  the  stock  solution  of DFTPP  described  in  Test
        I.  The dilutions  should  have  the concentrations  of ten  micrograms
        per milliliter,  five micrograms  per  milliliter,  one microgram per
        milliliter,  and one-tenth  of a microgram per milliliter.   Other
        concentrations  are acceptable  and may be required for open tubular
        columns.

     2.  Follow the basic procedures given in Test I  and make  the following

                                       8

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   series of injections (other sequences may be used, these are
   examples):
     Amount Injected

           50 nanograms
           20 nanograms
           10 nanograms
            5 nanograms
            1 nanogram
          100 picograms
Volumes and Standards

     5 ul  of 10 ug/ml standard
     4 ul  of 5 ug/ml standard
     2 ul  of 5 ug/ml standard
     1 ul  of 5 ug/ml standard
     1 ul  of 1 ug/ml standard
     1 ul  of 0.1 ug/ml  standard
3. List the masses and relative abundances of the background subtracted
   spectra of DFTPP.  Subtract the background spectra as described in
   Test I.  If necessary use an extracted ion current profile to locate
   the GC peak.  Discard all spectra that do not meet the criteria in
   Table 2.  If additional dilutions or measurements are necessary, do
   them.

4. For each of the remaining spectra compute the ratio R as follows:

                       DFTPP
               R =
                       BACK6D
   where:
       DFTPP = the summation of the relative abundances of the ions at
       masses 127, 255, 275, 441, 442 and 443

       BACK6D = the summation of the relative abundances of the six most
       abundant non-DFTPP background ions.  Background ions with less
       than 3% relative abundance are assigned a value of 3.  If all
       background is less than 3% relative abundance, this term is 18.
       Table 3 contains all  DFTPP ions over 3% relative abundance and
       Table 4 contains a group of common background ions.

   Prepare a plot of R values as a function of amount injected.  The
   instrument detection limit defined in this test is for the complete,
   valid spectrum with a defined level of acceptable noise.  This
   detection limit is the amount injected that gives an R value of
   five.  If sufficient points are available, a good estimate of the
   instrument detection limit may be obtained from a first or second
   order regression on this  data.

   The rationale for the selection of an R value of five is consistent
   with the previous statement that background ions should be less than
   about 10% of the total ion abundance in an interpretable spectrum.
   The average relative abundance of the six DFTPP ions used to compute
   R is in the 25-35% range.  For an R value of five the average
   relative abundance of the six background ions will be in the 5-7%
   range,  and it is estimated that all background ions under these
   conditions will be less than 10% of the total ion abundance.

-------
       TABLE 3. IONS OVER 3% RELATIVE ABUNDANCE  OBSERVED
                IN THE 70 ev MASS SPECTRUM OF  DFTPP
 AMU

 50.0
 51.0
 69.0
 74.0
 75.0
 77.0
 78.0
 93.0
 99.0
107.0
110.0
117.0
127.0
128.0
129.0
167.0
168.0
186.0
187.0
198.0
199.0
205.
206.
207.
217.0
221.0
224.0
227.0
244.0
255.0
256.0
274.0
275.0
276.0
296.0
423.0
441.0
442.0
443.0
.0
.0
.0
                   INTENSITY
                         [

                      8.11
                     34.60
                     32.93
                      3.10
                      4.53
                     34.84 -
                      3.10
                      3.10
                      3.81
                     10,97
                     20.76
                      6.44
                     37.70
                      3.10
                     12.88
                      4.05
                      4.77
                     13.12
                      3.81
                    100.00
7.
5.
  ,15
  .01
20.28
 4.53
 5.01
 4.29
11.21
  .81
   11
                      3.
                      8.
                     49.16
                       .39
                       .29
7.
4.
                     23.15
                        81
                        01
                        34
                      9.30
                     69.45
                     12.88
              PERCENT OF TOTAL INTENSITY

                      1.11
                      4.74
                      4.51
                      0.42
                      0.62
                      4.77
                      0.42
                      0.42
                      0.52
                        .50
                        .84
 0.88
 5.16
 0.42
 1.76
 0.55
 0.65
 1.79
 0.52
13.69
 0.98
 0.68
 2.77
 0.62
 0.68
 0.58
 1.53
 0.52
 1.11
 6.73
 1.01
 0.58
 3.17
 0.52
 0.68
 0.45
 1.27
 9.51
 1.76
                              10

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               TABLE 4.   COMMON BACKGROUND IONS IN GC/MS SYSTEMS
        Masses

        41,43,55,57,
        69,71,81,83,
        85,95,97,99

        149
        73,, 101,135,197,207
        259,345,346,355
        169,261
Sources

Saturated hydrocarbons and
unsaturated hydrocarbons -
cyclic and open chain-many sources

Phthalate esters used as plasticizers
in tubing, etc.

Methyl and phenyl silicone
polymers used in stationary
phases, diffusion pump oil, etc.

Polyphenyl ether diffusion
pump oil
    The required  instrument  detection  limits,  at an R value of five,  are 50
nanograms  for  systems  used  in  the  analyses  of  industrial  or municipal
wastes, and  30  nanograms  for systems used  in analyses of  ambient or drinking
waters.  These  limits  were obtained from considerations of EPA recommended
sample sizes and  concentration  factors.  If a  system cannot meet these
criteria,  maintenance  or  repair is required.   Particular  attention should be
given to those  items mentioned  in the  second paragraph of this test.

    Observed detection  limits with this  test are as follows:

    1. A Finnigan 3200  equipped with a Varian  1400  GC,  a  packed 1% SP 2250
       Column (Table 1),  a Systems Industries  RIB interface,  and a PDP-8
       datasystem (disk)  gave a detection  limit  of  five nanograms.

    2. A Finnigan 4000  with  a Finnigan 9610 GC,  a packed  1% SP 2250 column
       (Table 1), an INCOS interface,  and an INCOS  datasystem (Nova 3,  disk)
       gave a detection limit of 25 nanograms.

IV.  Saturation Recovery  Test

    The purpose of this test is  to evaluate the  ability of a  system to
measure the spectrum of a test  compound  at  a low level  immediately  after a
relatively large quantity of another compound  entered  the  system.   This
situation occurs frequently  in  real environmental samples,  especially waste
samples where a very large concentration of one  component  may saturate  the
detector,  and within a few minutes or  less  a very small quantity of a
compound of interest may enter  the detector.

Procedure:

    1. Prepare an acetone solution containing five milligrams  per milliliter
       of £-bromobiphenyl  and 20 micrograms per milliliter  of  DFTPP.  A
       second solution containing approximately  50 micrograms  per milliliter

                                    11

-------
       of each is optional and may be useful to optimize chromatographic
       conditions.                 ;

    2.  Establish GC conditions such that the DFTPP elutes within two minutes
       after the elution of the £-bromobiphenyl.  These conditions were
       achieved with a 6' x 2 mm ID' glass column packed with  1% SP2250 on
       Supelcoport (100/120 mesh) using a flow of 30 ml of helium per minute
       with the initial column temperature at 120°C and programming to
       230°C at 10° per minute.  The ]3-bromobiphenyl eluted at 110
       seconds and the DFTPP at 210 seconds.  This test is carried out using
       the same basic operating parameters given in Test I.

    3.  Inject two microliters of the standard solution containing the 250:1
       ratio of £-bromobiphenyl to JDFTPP.  Plot the DFTPP spectrum as in
       Test I.  Each of the ions at! masses 152, 232, and 234, which are the
       three most abundant in the spectrum of £-bromobiphenyl, must be below
       5% relative abundance in the| background subtracted spectrum of DFTPP.
                                   I
V.  Precision Test

    The purpose of this test is to measure the precision of the GC/MS system
in quantitative analysis using continuous, repetitive measurement of spectra.
This test evaluates precision fromjfilling a syringe to integration of the
peak area for a specific quantisation ion.  The entire test should be
carried out on the same day by the isame technician.  The application of an
automatic sample changer in this test is required if it will  be used for
normal  sample processing.  This shcjuld be documented in the test results.
If acceptable precision cannot be obtained with this test, the precision of
a complete anaytical method may also be unacceptable.
                                   j
Procedure:

    1.  Select a group of seven or more compounds, and prepare a standard
       solution in acetone that contains the entire group.  Some recommended
       compounds are in Table 5, and the concentration of each should be 20
       micrograms per mi Hi liter.  !This group of compounds must include a
       chlorinated hydrocarbon that may decompose on a hot metal surface and
       a polycyclic aromatic hydrocarbon with a molecular weight greater
       than 200.  For compounds amenable to the inert gas purge and trap
       procedure, prepare the standard solution in methanol at the same
       concentration.  The purge arid trap mixture must include chloroform,
       bromoform, sym-tetrach1oroethane, and p-bromofluorobenzene.  Some
       recommended compounds are in Tables 9-12.  This test may be conducted
       with either or both groups of compounds.
                                     12

-------
  TABLE 5.  PRECISION STATISTICS FOR TEN PRIORITY POLLUTANTS PLUS OCTADECANE
COMPOUND


1,3-DICHLOROBENZENE

NAPHTHALENE

1,2,4-TRICHLOROBENZENE

n-OCTADECANE

DIMETHYL PHTHALATE

DI-ji-BUTYL PHTHALATE

N-NITROSODIPHENYLAMINE

HEXACHLOROBENZENE

PYRENE

CHRYSENE

BENZO(A)PYRENE
:GRATION
MASS
146
128
180
254
163
149
169
284
202
228
252
PEAK1
TYPE
N
N
N
N
N
;N
N
N
N
B
B
MEAN
AREA
6771
18077
5412
345
13540
21770
6460
4027
18107
10345
9518
(S/MEAN .
S *100
278
375
195
15
501
364
228
139
607
636
681
4.1
2.1
3.6
4.2
3.7
1.7
3.5
3.4
3.4
6.2
7.2
   = narrow; B = broad (see text for definitions)
        Select an appropriate GC column.  For compounds similar to those in
        Table 5, the columns in Table 1 are satisfactory.  For compounds,
        amenable to purge and trap procedures, two acceptable columns are an
        8 ft. stainless steel or glass column packed with 1% SP-1000 coated
        on 60/80 mesh Carbopack B or packed with 0.2% Carbowax 1500 coated
        on 60/80 mesh Carbopack C.  Prepare for data acquisition with the
        following variables:

        mass range:  35-350 amu (For purge and trap compounds use 20-260 amu)
        scan time:  approximately two to six seconds (two or three seconds
                    with open tubular columns)
        electron energy:  70 ev
        electron multiplier:  not to exceed that recommended by the
                              supplier for the age of the device.

        Inject with a syringe or automatic sample changer four micro! iters
        (80 nanograms of each compound) of the standard solution and acquire
        data until all compounds have eluted from the column.  Save the data
                                      13

-------
4.
        file on the data system and repeat the injection a minimum of four
        times, saving the data files in each case.

        Plot the total ion current profiles, and use a quantisation program
        to integrate peak areas in arbitrary units (usually
        analog-to-digital counts) over a specific quantisation mass for each
        compound in each data file.  ! Precision may be evaluated using either
        the peak areas in arbitrary Units or ratios of peak areas.  The
        former gives a precision representative of external standardization,
        and the latter a precision representative of internal
        standardization.  There willlbe no significant difference in the
        results using the two methods if the system is operating properly
        and acceptable syringe filling and injection techniques are used.
        It is recommended that calculations be carried out using both
        methods for comparison of results, but the minimum requirement is
        that precision be evaluated Using the method that corresponds to the
        standardization procedure used in the laboratory for environmental
        samples.                     '

        Table 5 is an example of data from five replicate syringe injections
        of 80 nanograms of each compound using a Finnigan 3200 and a PDP-8
        based data system.  The mean areas are in analog-to-digital
        converter units and the standard deviations (S) were computed using
        the equation below.  The last column in Table 5 is the relative
        standard deviation which is (S/mean area)* 100.  Table 6 contains
        the results of computations with exactly the same raw data as in
        Table 5, but using ratios of areas as in internal standard
        calibrations.  The response factor (RF) is defined in test VII, and
        the mean response factors are shown in Table 6.  The compound
        di~n-butylph thai ate was selected as the internal standard because it
        showed the smallest variation in peak area (1.7%, Table 5) and
        eluted near the mid-point in the chromatogram.  The standard
        deviations and relative standard deviations were computed as in
        Table 5.
                   N
                            N
       S =
             N :€Area  . - ( ^ Area.)'
              1=1      1     i=l      n
                       N (N-l)
         where :
               S = the standard deviation

               N = the number of measurements
                   for each compound

               Area = the integrated ion abundance of the
                      quantisation mass

    The compounds designated as having narrow peak types in Tables 5 and 6
had widths at half height of 45 seconds or  less.  The mean relative standard

                                      14

-------
          TABLE 6.  PRECISION STATISTICS USING AN  INTERNAL STANDARD
COMPOUND





1,3-DICHLOROBENZENE



NAPHTHALENE



1,2,4-TRICHLOROBENZENE



Jl-OCTADECANE



DIMETHYL PHTHALATE



DI-n-BUTYL PHTHALATE



N-NITROSODIPHENYLAMINE



HEXACHLOROBENZENE



PYRENE



CHRYSENE



BENZO(A)PYRENE
INTEGRATION
MASS
146
128
180
254
163
149
169
284
202
228
252
PEAK1
TYPE
N
N
N
N
N
N
N
N
N
B
B
MEAN
RF
0.3112
0.83048
0.2486
0.0158
0.62202
1.00000
0.2968
0.1850
0.83171
0.4751
0.4370
(S/MEAN
S *100
0.01512
0.017250
0.008571
0.000838
0.022980
0.00000
0.01008
0.005899
0.023110
0.02619
0.0275
4.9
2.1
3.4
5.3
3.7
0
3.4
3.2
2.8
5.5
6.3
                                     15

-------
deviation for the data in Table 5 is|3.3%, and the corresponding mean from
Table 6 is 3.6 %.  Therefore there wpis no significant  difference  in  the
precision of external and internal standardization.  The requirement of  this
test is that the mean relative standard deviation of data from  narrow peaks
be 7% or less.  This requirement is based on the general observation that
data from inter laboratory comparisons is usually about a factor of two more
variable than single laboratory data, and this is a reasonable  requirement
for an acceptable system.

    The last two compounds  in Tables 5 and 6 gave broader peaks with peak
widths at half height of more than 45 seconds.  Measurements  of these are
more variable because of the changing baseline during  temperature
programming and other factors.  The mean relative standard  deviations from
Tables 5 and 6 are 6.7% and 5.9% respectively, and  internal  standardization
may have some slight advantage for these peaks but  there are  too  few data
points to judge the significance of this.  The requirement  of this test  is
that the mean relative standard deviation of data from broad  peaks be 13% or
less.  Again the rule of thumb on interlaboratory data was  used to establish
this requirement.

    If this test is conducted with compounds amenable  to the  inert gas  purge
and trap procedure, the compound £-bromofluorobenzene  must  be included  in
the mixture.  This compound  is a secondary spectrum validation  compound
which is used with GC columns that do not elute DFTPP. Therefore, after a
purge and trap column is  installed for this  test £-bromofluorobenzene may be
used as a daily check on  spectrum validity.  The  ion abundance  criteria  for
£-bromofluorobenzene are  in Table 7, and  these  are  consistent with the  DFTPP
criteria in Table 2.

      TABLE 7.  £-BROMOFLUOROBENZENE KEY  IONS  AND  ION  ABUNDANCE CRITERIA

         Mass                           Ion Abundance Criteria
           50
           75
           95

           96
          173
          174
          175
          176
          177

 VI.   Library  Search Test

     Minimum requirements for the library search are the availability of the
 EPA/NIH database which is distributed through the National Bureau of
 Standards.  The searchable database^may be a subset of the EPA/NIH database,
 but  the subset must contain at least 10,000 spectra of general and
 environmental interest and the Chemical Abstracts Service (CAS) registry
 numbers for each compound.  Programs must be available to allow the operator
20-40% of the base peak
50-70% of the base peak
base peak, 100% relative
abundance
5-9% of the base peak
less than 1% of the base peak
greater than 50% of the base peak
5-9% of mass 174
greater than 50% of the base peak
5-9% of mass 176
                                     16

-------
to  submit background corrected spectra to the  library  search,  and  receive  a
printed report of the search results.  The  spectra from one of the
experiments in Test V should be submitted to the  library search  system.
Each compound must be .identified as the most probable  by the library search,
except isomers that may have very similar 70 ev El mass spectra  should not
be  counted as incorrect.  The mean search time, including the time for
background subtraction, should be one minute or less.  Printed reports
should include CAS numbers.  During this test make several deliberate
typical operator errors, such as entry of an incorrect command and a
non-existent file name.  The data system should respond with an  intelligible
error message, and return to a logical continuation point.

VII.  Quantitative Analysis with Liquid-Liquid Extraction

    This test uses a variety of environmental pollutants to measure quanti-
tative accuracy and precision of the total  analytical method, but  without
the complications of real sample matrix effects.  The test is designed for
laboratories that conduct quantitative analyses of water samples with GC/MS
using continuous repetitive measurement of  spectra.  Therefore,  laboratories
dealing in other media should design a similar test based on some  standard
reference material.  The principal difference between this test  and Test V,
the precision test, is the consideration of potential errors and variations
due to:  (a) extraction of the compounds from a reagent water matrix; (b)
concentration of the extract to a small volume; and (c) standardization of
the measured areas in terms of the concentration  of the original sample in
micrograms per liter.  This is one of the tests that goes beyond equipment
performance, and may be used to evaluate the performance of laboratories
using GC/MS for organics analysis.

    It is recommended that the same standard solution of seven or  more
compounds that may have been prepared'for the precision test (Test V) be
used in this test since retention information is  already available, and the
concentrations are in an acceptable range.  However, new standards may be
used and the seven or more compounds should be at the 20 microgram per
milliliter level in acetone.

Procedure:

    1.  Add 250 microliters (five micrograms of each compound)  of  the mixed
        standard solution in acetone to each of a minimum of five  liters of
        reagent water.  This aqueous solution is called a laboratory control
        standard (LCS).  Set aside one additional  liter of reagent water as
        a reagent blank.

    2.  Carry out the extractions according to the established procedures
        (2,3,4).  The methylene chloride extract must be concentrated to 0.5
        milliliter.  The reagent blank should be measured first by itself,
        and if significant contamination is found, correct the problems
        before proceeding with this test.   See the references cited above
        for information on the interpretation of blanks.
                                      17

-------
3.
4.
5.
Select  an  appropriate  column  (Test  V),  and  prepare  for  data
acquisition using the  GC/MS operating parameters  given  in  Test V.
Inject  four microliters  of each  of  the  concentrated extracts,  and
obtain  GC/MS data from each injection.   Save  all  of the data files
from the minimum of five extracts.   Quantisation  may be accomplished
with either internal or  external  standardization.   If an external
standard will be used, this is  already  prepared and is  the solution
used to prepare the laboratory  control  standards.   Inject  two
microliters (40 nanograms) of the external  standard and acquire data
using the  same acquisition parameters.

If an internal standard  will  be  used, add five microliters of  a one
milligram  per mi Hi liter solution of the internal standard to  each
of the  0.5 milliliters of concentrated  extract.   This corresponds  to
the addition of five micrograms  of  the  internal standard in such a
way as  to  not significantly change  the  volume of  the concentrated
extract.   Inject four  microliters of each extract as above and save
all data files.  If an internal  standard is used  it will be
necessary  to measure the response factors (RF) in a separate
experiment with standards (no extraction).  The response factors are
computed with the following equation:
                      Area  (X)
        RF


    where:
                    Amount  (XJ
                  Area  (Sj
                Amount  (S)

         Area(X)     =  the peak  area of  the  compound  in
                        consistent units.
        Amount (X)  =  the quantity of the compound  injected
                       in consistent units.

        Area (S)    =  the peak area of the  internal  standard  in
                       consistent units.

      Amount (S)    =  the quantity of internal  standard
                       injectgd in consistent units.

Plot the total ion current profiles and use  a quantisation  program
to integrate peak areas in arbitrary units (usually
analog-to-digital converter counts) over  a specific  quantisation
mass for each compound in each data file.  If an  internal standard
was employed computations in terms of response factors  are
acceptable.

Precision and accuracy is expressed in terms of  the  percentages of
the true values (P) measured |in the experiments  and  the statistical
variations in the data.  The standard deviations  (S)  and the
relative standard deviations (S/mean P) *100, are computed  as
described in Test 5.  With an external standard  P is  computed  as
follows:
                                  18

-------
            p  _       area  (concentrated  extracts) *100
                           area  (external  standard)•

        With an  internal standard P  is computed with the equation  below
        which  assumes the  response factors  are defined  as  above:


             p _      area (concentrated  extract)   *100
                        area  (internal standard)*RF

    Table 8 shows precision and accuracy  data obtained  for eight compounds
extracted from reagent water  with methylene chloride and measured  with GC/MS
using a single external standard.  The GC/MS was a Finnigan model  3200 with
a PDP-8 based  datasystem.  One  difference between the data in Table 8 and
the procedures described in this test is  that the data  in Table 8  represents
duplicate extractions and  measurements at four different concentration
levels between 15-200 micrograms per liter for each compound.  Figures 1 and
2 show control charts which contain  all eight P values  for each of two of
the compounds.  This  is a  recommended method (5) of displaying precision and
accuracy data.  Charts should be labelled as in Figures 1 and 2.   General
experience shows that P values measured over a concentration range of one or
two orders of magnitude are often concentration independent within the
precision of the method.

    The mean of the P values  (grand  average) in Table 8 is 84%.  Therefore,
the requirement of this test  is that the grand average  P value of  the
compounds used in this test must be  in the range of 68-132%.  Again, as in
Test V, the expectation is that multi-laboratory data will usually be about
a factor of two more variable than single laboratory data.  The mean
relative standard deviation from Table 8  is 19%, and the requirement of this
test is that the mean relative standard deviation be 38% or less.

VIII.  Quantitative Analysis with Inert Gas Purge and Trap

    This test uses a variety of environmental  pollutants to measure
quantitative accuracy and  precision of the total analytical method, but
without the complications  of real  sample matrix effects.  The test is
designed for laboratories  that conduct quantitative analyses of water
samples with GC/MS using continuous repetitive measurement of spectra.
Therefore, laboratories dealing in other media should design a similar test
based on some standard reference material.  The principal  difference between
this test and Test V, the  precision test, is the consideration of  potential
errors and variations due  to:   (a) purging of the compounds from a reagent
water matrix; (b) trapping and desorption of the compounds; and (c)
standardization of the measured areas in terms of the concentration of the
original sample in micrograms  per liter.   This test is required to evaluate
purge and trap equipment that  is delivered as  an integral  part of  a GC/MS
system, or other purge and trap equipment that is interfaced to the GC/MS
system.

    The series of experiments  in this test is  used to generate three key
pieces of information about purge and trap performance:

                                     19

-------
      TABLE 8.   PRECISION AND ACCURACY DATA FOR LIQUID-LIQUID EXTRACTION
                     WITH GC/MS AND AN EXTERNAL STANDARD
COMPOUND
NITROBENZENE
1,2,3-TRICHLOROBENZENE
NAPHTHALENE
ACENAPHTHYLENE
N-NITROSODIPHENYLAMINE
FLUORANTHENE
PYRENE
n-BUTYLBENZYLPHTHALATE
INTEGRATION
MASS
123
180
128
152
169
202
202
206
MEAN
P
94
85
73
83
89
80
83
86

S
8.8
13
18
15
19
19
19
17
(S/MEAN P)
*100
9.4
15
25
18
21
24
23
20
                                      20

-------
Compound: nitrobenzene
Range: 50 - 200jug/l
Method: extraction, CH2CI2
Relative standard deviation: 9%
                               Data acquisition : 35 - 400amu
                               Quantitation: mass 123, one
                                           external standard
                                                  MEAN + 3S


§
CO
0)
1-
•*-
m

c

-------
Compound: pyrene
Range: 15 - 130^ig/l
Method: extraction, CH2CI2
Relative  standard deviation: 23%
Data acquisition: 35 - 400 amy
Quantitation: mass 202, one
            external standard
                                                  MEAN + 3S
ItW
130
120
110-
J
£100-
0
E 90-
•»-
0 80

-------
     (a) Method efficiency for test compounds by comparison of the measured
         quantity from syringe injection into the GC with the quantity
         measured after purging, trapping, and desorptipn.  Because of the
         method of calibration used in the purge and trap procedure high
         method efficiency as defined above is not necessary for acceptable
         precision and accuracy.  However, high method efficiency is required
         for acceptable sensitivity, and low method efficiency will result in
         unacceptable detection limits.  Also in the case of real samples, a
         low method efficiency combined with an unfavorable matrix effect
         could render the method totally useless.

     (b) Precision of the overall  purge, trap, desorption, and GC/MS analysis.

     (c) Accuracy of the overall purge, trap, desorption, and GC/MS analysis
         in terms of the percentage of the true value found in laboratory
         control  standards.

     All the above information may be obtained from the same set of data.   It
is  recommended that the same standard solution of seven or more compounds
amenable to purge and trap that was recommended for the precision test (Test
V) bt?  used in this test since retention information may be already
avail av^le, and concentrations are in an acceptable range.'  However, new
standards may be used, and the seven or more compounds should be at the 20
microgratfi15 per milliliter level in methanol.  The purge and trap mixture
must incline chloroform, bromoform, sym-tetrachloroethane and
2-bromofluo)"°kenzene.

Procedure:

    1.  Select c?n  Appropriate column (see Test V) and prepare for data
        acquisition  u'sing the GC/MS operating parameters given in Test V.

    2.  Add five micro Triers (100 nanograms of each compound) of the mixed
        standard in roethartp] to each of a minimum of five aliquots of  .
        reagent water.   A  z£FP dead volume syringe is strongly recommended
        for this transfer.   Purge and trap samples may be 5 ml to 25 ml,  but
        5 ml  is recommended  for op*"^1"11 method efficiency.   This aqueous
        solution is called a laboratory control  standard.

    3.  Carry out the purge  and trap  accon^Q9 to the established procedures
(2,3,4)  at ambient temperature.   A      nt water blanK should be
          ,,                  eraure.    rec
        measured first and at occasional interval*0  detect instrument
        contamination.  If significant contamination^?  found,  correct the,_
        problems before proceeding with this test.  See":r?ferences  C1'ted
        above for information on the interpretation of
                                                   !
        Purge, trap, desorb, and obtain GC/MS data from a minimum i^T-
        laboratory control standards and save all the data files.  At
        the midpoint of the purge and trap analyses, inject with a sy
        five microliters (100 nanograms of each compound) of the mixed
        standard in methanol into the purge and trap GC column.  A zero dead
                                     23

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    volume syringe is strongly recommended for this injection.  Acquire
    GC/MS data using the same acquisition parameters used for purge and
    trap analyses.

5.  Plot the total ion current profiles, and use a quantisation program
    to integrate peak areas in arbitrary units (usually analog-to-
    digital converter counts) oyer a specific quantisation mass for each
    compound in each data file.
                               I
6.  Method efficiency must be evaluated by comparing the measured areas
    from direct GC injection with the corresponding areas from the
    purge, trap, and desorption experiments.  Internal standards cannot
    be used for this evaluation because method efficiencies for various
    compounds are not yet known 1,  and comparable response factors cannot
    be computed for direct injection and purge/trap/desorption.

    Prepare a table similar to Table 9 which shows data obtained with a
    Finnigan model 3200, a PDP-8 data system, and a Tekmar model LSC-1
    purge and trap device with a 25 ml sample container.  The equation
    used to compute method efficiencies (E) is shown below.  The minimum
    requirement of this test is that the mean of the mean (grand
    average) method efficiencies of the compounds used in this test be
    70% or more and all compounds must be recovered with at least 30%
    efficiency.  Also the spectrum obtained from £-bromofluorobenzene
    must meet the ion abundance criteria given in Table 7.  If these
    requirements cannot be met, the system is unacceptable for
    quantitative analyses and needs repair or redesign.  One critical
    method variable that may be optimized is the purge gas flow rate.
                       area (after purge and trap)
                       area (direct injection)
*100
7.  Precision and accuracy data1may be obtained by choosing one of the
    experiments in the purge and trap set as a standard, and computing
    the percentages of the true values (P) measured in the other
    laboratory control standards.  This is consistent with the standard
    method of calibration used with the purge and trap method.  The
    experiment chosen as the standard may either be treated as an
    external standard, or may be used to compute response factors for an
    internal standard calibration.  Table 10 shows the data from the
    method efficiency determination recomputed by ignoring the direct
    injection result, and using one of the purge and trap experiments as
    an external standard.  The equation used to compute the percentages
    of the true values (P) is as follows:
              P =
area (after purge and trap)
area (external standard)
*100
    The standard deviation of P and relative standard deviation were
    computed as described in Test V.  The mean of the P values (grand
    average) in Table 10 is 95% and the mean relative standard deviation

                                  24

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TABLE 9.  METHOD EFFICIENCIES FOR SOME PRIORITY POLLUTANTS
                PLUS £-BROMOFLUOROBENZENE
INTEGRATION
COMPOUND MASS
CHLOROFORM
CARBON TETRACHLORIDE
BROMODICHLOROMETHANE
TRICHLOROETHYLENE
DIBROMOCHLOROMETHANE
BROMOFORM
TETRACHLOROETHYLENE
Sym-TETRACHLOROETHANE
£-BROMOFLUOROBENZENE
83
117
83
130
129
173
166
83
174
MEAN AREA
PURGE/TRAP
2883
2289
2925
1474
1572
1241
1737
1032
1542
AREA DIRECT
INJECTION
3001
2314
3280
1653
2343
2788
2102
3071
2200
MEAN METHOD
EFFICIENCY^)
96
99
89
89
67
45
83
34
70
                            25

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        TABLE 10.  PRECISION AND ACCURACY DATA FOR THE PURGE AND TRAP
                 ANALYSIS WITH GC/MS AND AN EXTERNAL STANDARD
COMPOUND

CHLOROFORM
CARBON TETRACHLORIDE
BROMODICHLOROMETHANE
TRICHLOROETHYLENE
DIBROMOCHLOROMETHANE
BROMOFORM
TETRACHLOROETHYLENE
Sym-TETRACHLOROETHANE
£-BROMOFLUOROBENZENE
INTEGRATION      MEAN
   MASS           P
        (S/MEAN P)
S         *100
83
117 :
83 :
130
129
173
166
83
174
92
97
96
94
98
96
96
100
90
8.8
7.9
7.2
7.4
4.4
5.2
14
14
12
9.5
8.2
7.5
7-9
4.5
5.4
14
14
14
                                    26

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        is 9.4%.  The requirement of,this test is that the grand average of
        the P values of the compounds used in this test must be in the range
        of 90-110%.  This is based on the general rule, described in Test V,
        that data from interlaboratory comparisons is usually about a factor
        of two more variable than single laboratory data.  The mean relative
        standard deviation must be 19% or less on the same basis.

        The percentages of the true values (P) may also be computed by
        selecting one compound in the test mixture as an internal standard,
        and using one of the purge and trap experiments to establish
        response factors as defined in Test VII.  The percentages of the
        true values (P) in the other laboratory control standards are
        computed as follows (the terms have the same meaning defined in Test
        VII):
              P =
area (x) * 100
area (s) *RF
    Table 11 shows the method efficiency data recomputed with
2-bromofluorobenzene as the internal standard.  Response factors were
established with the same purge andd trap experiment that was used as an
external standard for the computations in Table 10.  Table 12 shows the same
data recomputed with dibromochloromethane as an internal standard.  Again,
response factors were established with the same purge and trap experiment
that was used as an external standard for the computations in Table 10.

    The internal standard calculations reveal that the percentages of the
true values observed and the relative standard deviations are a function of
the internal standard selected.  The compound 2-bromofluorobenzene eluted
late in the chromatogram after temperature programming, and measurements of
it were more variable because of this and other factors.  This is reflected
in the grand average of the P values from Table 11 of 108% and the mean
relative standard deviation of 12%.  The compound dibromochloromethane
showed the least variation in the external standard data (Table 10) and is
an excellent internal standard.  The grand average of the P values from
Table 12 is 97% with a mean relative standard deviation of 6.5%.  This
illustrates that care must be exercised in the selection of an internal
standard because of the potentially significant impact on the observed
precision and accuracy.  The individual P values may also be charted as in
Figures 1 and 2 to provide a graphic presentation of the data.

IX.  Qualitative Analysis with Real Samples

    The purpose of this test is to-evaluate the ability of the GC/MS system,
laboratory, and sample preparation methods to deal with natural background,
interferences, and sample matrices found in real environmental samples.  The
test is limited to qualitative analyses because of the unpredictable
quantitatvie effects of the sample matrix.  This is one of the tests that
goes beyond equipment performance, and it may be used to evaluate the
performance of laboratories using GC/MS for organics analysis.  The test is
designed for laboratories that conduct qualitative analyses of water samples
with GC/MS using continuous, repetitive measurement of spectra.

                                     27

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        TABLE 11.  PRECISION AND ACCURACY DATA FOR THE PURGE AND TRAP
      ANALYSIS WITH 6C/MS AND THE  INTERNAL STANDARD £-BROMOFLUOROBENZENE
COMPOUND

CHLOROFORM
CARBON TETRACHLORIDE
BROMODICHLOROMETHANE
TRICHLOROETHYLENE
DIBROMOCHLOROMETHANE
BROMOFORM
TETRACHLOROETHYLENE
j&m-TETRACHLOROETHANE
£-BROMOFLUOROBENZENE
INTEGRATION      MEAN
   MASS           P
        (S/MEAN P)
S         *100
83
117
83
130
129
173
166 ;
83
174
103
108
107
105
110
108
107
112
100
13
12
12
12
11
12
13
19
0
13
11
11
11
10
11
12
17
0
                                      28

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        TABLE 12.  PRECISION AND ACCURACY DATA FOR THE PURGE AND TRAP
      ANALYSIS WITH 6C/MS AND THE INTERNAL STANDARD DIBROMOCHLOROMETHANE
COMPOUND


CHLOROFORM

CARBON TETRACHLORIDE

BROMODICHLOROMETHANE

TRICHLOROETHYLENE

DIBROMOCHLOROMETHANE

BROMOFORM

TETRACHLOROETHYLENE

Sym-TETRACHLOROETHANE

£-BROMOFLUOROBENZENE
INTEGRATION
MASS
83
117
83
130
129
173
166
83
174
MEAN
P
94
98
98
95
100
98
98
101
92
S
5.8
4.3
3.7
3.8
0
2.0
9.8
11
9.7
(S/MEAN P)
*100
6.2
4.4
3.7
4.0
0
2.0
10
11
11
                                     29

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Procedure:

    1.  Acquire  appropriate  quality  control  samples  containing  a  number  of
        organic  compounds  dissolved  in  acetone, methanol,  or other
        water-miscible  organic  solvent  and sealed  in  all-glass  ampuls.   The
        concentration levels  should  be  suitable for  the preparation  of
        aqueous  samples  in the  10-500 microgram per  liter  range by addition
        of one ml  or less  of  the  organic  solution  to  the environmental
        sample.   Instructions for the dilutions should be  supplied with  the
        samples,  but the identity of the  compounds in the  ampuls  should  be
        supplied  separately to  the laboratory management.  A number  of
        samples  of this type  will be available in  1980 from:

                        Quality Assurance Branch
                        EMSL-Cincinnati
                        Environmental Protection Agency
                        Cincinnati!, Ohio  45268
                                  i
    2.  Obtain an  environmental sample  typical of  the type normally  analyzed
        in the laboratory.  Add th£ quality  control  samples to the
        environmental samples according to the instructions provided, and
        proceed with the analyses using the  appropriate method, e.g., as in
        Tests VII  and VIII.

    3.  Plot the total  ion current profiles  and identify all the  compounds
        using the  mass  spectra.  All compounds must  be correctly  identified
        except, as in the  library search, isomers with nearly identical
        70 ev electron  ionization spectra should not  be counted as incorrect.

X.  Solid Probe Inlet System  Test (optional)

    The purpose of this test  is to evaluate  the critical thermal  character-
istics of the solid probe inlet system, and  to determine whether  valid
spectra are produced with this  system.  The  test uses cholesterol which  is
sensitive to thermal effects.   Data acquisition is by continuous  repetitive
measurement of spectra.

Procedure:

    1.  Prepare a  standard solution of cholesterol in acetone at  a concen-
        tration of 250 micrograms per milliliter.   Evaporate one micro!iter
        of this solution in the solid probe  sample holder.

    2.  Use the data acquisition parameters  given in  Test  I, and  gradually
        heat the sample until the cholesterol pressure increases  and spectra
        may be measured.

    3.  Terminate  data acquisition and plot  a background subtracted spectrum
        of cholesterol  as described in Test  I.   Measure the abundances of
        the ions at masses 386  and 368, and  compute the 386/368 abundance
        ratio.  This should be 3.0 or greater for an  acceptable solid probe
        inlet system.  The ion  abundance  at mass 387  should be 26-34% of the

                                      30

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abundance at mass 386.  Finally large ions above 30% relative
abundance should be at masses 41,  43, 55,  57,  67, 69,  71,  79, 81,
83, 91, 93, 95, 105, 107, 109, 119,  121,  133,  145,  147,  149,  159,
161, 213, 275, 301, and 386.
                              31

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                                  SECTION 4

                                  REFERENCES
1.  Eichelberger, J.W., L.E. Harris, and W.L. Budde, "Reference Compound to
    Calibrate Ion Abundance Measurements In Gas Chromatography - Mass
    Spectrometry Systems," Anal. Chem., 47, 995 (1975).

2.  Budde, W.L., and J.W. Eichelberger, "An EPA Manual  for Organics Analysis
    Using Gas Chromatography - Mass Spectrometry," EPA Report No. EPA
    600/8-79-006, March, 1979.

3.  Budde, W.L., and J.W. Eichelberger, "Organics Analysis Using GC/MS," Ann
    Arbor Science Publishers, Ann Arbor, Michigan, July 1979.

4.  "Guidelines Establishing Test Procedures for the Analysis of
    Pollutants," Federal Register,iVolume 44, No. 233,  p.  69532-69552,
    (December 3, 1979).

5.  "Handbook for Analytical Quality Control in Water and Wastewater
    Laboratories,"  EPA Report No. EPA-600/4-79-019, March, 1979, Chapter 6.
                                     32

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                                    TECHNICAL REPORT DATA
                             (Please read Instructions on the reverse before completing)
 1. REPORT NO.
  EPA-600/4-80-025
                                                             3. RECIPIENT'S ACCESSION'NO.
 4. TITLE AND SUBTITLE
  Performance Tests  for the Evaluation  of Computerized
  Gas  Chromatography/Mass Spectrometry  Equipment and
  Laboratories
                 5. REPORT DATE
                  April  1980 issuing date
                 6. PERFORMING ORGANIZATION CODE
 7. AUTHOR(S)
                                                             8. PERFORMING ORGANIZATION REPORT NO.
  William L.  Budde and  James W. Eichelberger
 9. PERFORMING ORGANIZATION NAME AND ADDRESS
                                                             10. PROGRAM ELEMENT NO.
   SAME AS  BELOW
                                                               1BD884
                 11. CONTRACT/GRANT NO.
                                                               In-House
 12. SPONSORING AGENCY NAME AND ADDRESS
 Environmental  Monitoring &  Support Lab,
 Office of  Research and Development
 U.S. Environmental Protection Agency
 Cincinnati,  Ohio 45268
- Cinn, OH
                                                             13. TYPE OF REPORT AND PERIOD COVERED
                 14. SPONSORING AGENCY CODE

                   EPA/600/06
 15. SUPPLEMENTARY NOTES
 16. ABSTRACT
  A series of  ten general purpose tests are described which are  used to evaluate
  the performance of computerized gas chromatography-mass spectrometry systems.
  All of the tests use the continuous, repetitive measurement  of spectra method
  of data acquisition, and no  selected ion monitoring tests are  included.
  Evaluation criteria are given  with each performance test.  Some of the tests
  go beyond equipment performance,  and may be  used to evaluate the performance
  of laboratories using GC/MS  for organics analysis.
 17.
                                 KEY WORDS AND DOCUMENT ANALYSIS
                   DESCRIPTORS
                                               b.lDENTIFIERS/OPEN ENDED TERMS
                               c.  COSATI Field/Group
 Mass  Spectroscopy
 Spectroscopic Analysis
 Organic compounds
                                    1402
                                    0703
 18. DISTRIBUTION STATEMENT

 Release to Public
    19. SECURITY CLASS (ThisReport)'
       Unclassified
21. NO. OF PAGES

     41
                                               20. SECURITY CLASS (This page)
                                                  Unclassified
                                                                           22. PRICE
_g£A Form 2220-1 (9-73)
                                             33
                                                                    * U.S. GOVERNMENT PRINTING OFFICE: 1980-657-146/5664

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