United States
                     Environmental Protection
                     Agency
 Environmental Monitoring and
 Support Laboratory
 Cincinnati OH 45268
                     Research and Development
 EPA-600/S4-84-054 July 1984
&ERA         Project  Summary

                    EPA  Method  Study  29,
                    Method  624 —  Purgeables
                      The work which is described in the
                     report was performed for the purpose of
                     validating,  through an interlaboratory
                     study, proposed Method 624 for the
                     analysis of the volatile organic priority
                     pollutants.  This method  is based  on
                     purging  and  concentration of the
                     various  analytes on  an adsorbent
                     followed by thermal desorption onto a
                     gas chromatographic  column.  A low
                     resolution mass spectrometer serves as
                     the measuring device.
                      Participating laboratories were se-
                     lected based upon technical evaluation
                     of  proposals and upon the analytical
                     results of prestudy samples. The labora-
                     tories were supplied with ampuls
                     containing  various  concentrations of
                     the pollutant compounds. These solu-
                     tions were aliquoted into four different
                     water types which were subsequently
                     analyzed  according to the appropriate
                     methods. In addition to the sample
                     concentrates, each laboratory was
                     supplied  with an industrial effluent
                     which was known to contain various
                     pollutants. The purpose of this sample
                     was to ascertain the propensity of the
                     method of produce false positives and
                     false negatives.
                      The data obtained from the interlab-
                     oratory study were analyzed employing
                     a series of computer programs known
                     as the Interlaboratory Method Validation
                     Study (IMVS) system which was de-
                     signed to implement ASTM procedure
                     O2777. The IMVS analyses  included
                     tests for the rejection of outliers (both
                     laboratory and individual), estimation
                     of mean recovery (accuracy), estimation
                     of single-analyst and overall precision,
                     and tests for the effects of water type
                     on accuracy and precision.
                      This report was submitted in partial
                     fulfillment of contract number 68-03-
                     3102 by Radian Corporation under the
 sponsorship of the U.S. Environmental
 Protection Agency. The report covers a
 period from January, 1982 to June,
 1983.
  This Project Summary was developed
 by EPA's Environmental Monitoring
 and  Support Laboratory. Cincinnati,
 OH,  to announce key findings of the
 research project that is fully documented
 In a separate report of the same title (see
 Project Report ordering information at
 back).
Introduction
  The various analytical laboratories of
the U.S. Environmental Protection Agency
(USEPA) gather water quality data to
provide information on water resources,
to assist research activities, and to
evaluate pollution abatement activities.
The success  of these pollution control
activities depends upon the reliability of
the data provided  by the laboratories,
particularly when legal action is involved.
  The Environmental Monitoring  and
Support Laboratory — Cincinnati (EMSL-
Cincinnati),  of the USEPA develops
analytical methods and conducts quality
assurance programs for the water labora-
tories. The quality assurance program of
EMSL is designed to  maximize  the
reliability and legal defensibility of all
water quality  information collected by
USEPA laboratories. The responsibility
for these activities of EMSL-Cincinnati is
assigned to  the  Quality Assurance
Branch (QAB). One of these activities is to
conduct interlaboratory tests of  the
methods. This study reports the results of
the validation effort on Method 624 for
the volatile organic compounds.
  The interlaboratory study of USEPA
Method 624 consisted of three distinct
phases. Phase I involved the preparation
and ampuling of concentrates of  the

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compounds. The prepared concentrations
were then verified using GC methods.
  The second phase involved the selection
of participating laboratories. Solicitations
were made for both paid participants and
volunteer participants.  Selection of
laboratories  was based on experience,
facilities, quality control procedures, and
cost estimates received from laboratories.
Final selection of fifteen laboratories was
made after the successful analysis of a
performance sample.  No laboratories
chose to participate  in  the  study as
volunteers.
  The third phase involved the conduct of
the study. The prepared  ampuls  were
distributed  to each laboratory.  Each
laboratory supplied the  required four
water types into which the ampuls were
spiked. In addition, a single water sample
was supplied by  Radian to evaluate the
method's tendencies  for false positives
and false negatives.  After analysis,
results were reported on  standard data
sheets.  Data were  keypunched  and
validated by  Radian. The final step in the
study was to conduct an  analysis of all
data  obtained using  USEPA's IMVS
computer programs.

Procedure
  The design of the interlaboratory study
of  Method  624 was based on the
technique described by W.J. Youden (1).
According to this technique, samples are
analyzed in pairs where the concentration
of each  analyte  in the sample pairs is
slightly different. The analyst is directed
to perform a single analysis and report
one value for each sample.
  The samples were prepared as concen-
trates  in sealed ampuls and shipped to
the participating laboratories.  Each
laboratory was responsible for supplying
laboratory pure water, finished drinking
water, a  surface water,  and an industrial
effluent water for use in the study (two
laboratories, numbers  10 and 16 used
water treatment plant  effluents which
may have had primarily municipal origins).
The analyst was  required  to  add an
aliquot of each concentrate to a value of
water from each of the four water types
and subsequently to  analyze the spiked
water samples.
  Sample pairs for each  method were
prepared at three  concentration levels;
low, medium, and high, all of which were
within the  linear range  of the  mass
spectrometer.
  In addition to the sample ampuls, an
industrial effluent  water selected by
Radian was furnished to each participating
laboratory for analysis.  This sample was
known to contain a number of the priority
pollutants and was judged to be some-
what difficult to analyze. The purpose of
the industrial effluent sample  was to
determine the propensity of the  method
to produce  false positives and false
negatives.
  After all analyses were completed, the
results  were subjected to statistical
analysis using USEPA's IMVS system to
determine the precision and accuracy of
Method  624.
Test Design
  The following is a summary of the test
design used based on Youden's nonrep-
licate technique for samples.
   1. Three Youden  pairs of  samples
     were analyzed for each analyte
     with the deviation from the mean of
     each pair being at least 5% but not
     more than 20%. The three pairs
     were spread over a usable and
     realistic range such that the lowest
     pair was somewhat  above the
     minimum  detection  limit and the
     upper  pair was within the linear
     range of the method.
   2. The spiking samples were supplied
     as  liquid concentrates in organic
     solvents  sealed in glass ampuls.
     Sufficient sample was provided to
     allow withdrawal of the appropriate
     amount of solution  to spike one
     water sample from each ampul.
   3. Twenty-four volatile organic ampuls
     were provided  to each of the 15
     laboratories.
   4. The concentrates were spiked into
     laboratory pure water,  drinking
     water, a  surface  water, and an
     effluent waste water  by the partici-
     pants prior to analysis. In addition,
     an  industrial effluent sample was
     supplied  to  each .laboratory by
      Radian. This  sample  was analyzed
     without addition  of  analyte con-
     centrates.
   5. Each of the 15 participating labora-
     tories was  furnished with the
     following materials:
       • Four Youden  pair ampuls of
          each  of three  concentration
          levels for the volatile organics.
          (A total  of 24 spiking sample
          ampuls.)
       • Sufficient  surrogate standard
          solution to analyze all samples
          and blanks.
       • A1 liter sample of an industrial
          effluent to be analyzed without
          addition of spiking sample.
       • Copies of Method 624.
       • A questionnaire covering dif-
          ficulties encountered with the
          method  and suggestions for  m
          improvements.
       • Data report forms to be com-
          pleted and returned to Radian.
       • A set of instructions detailing
          the method for  spiking the
          samples and the order in
          which samples were to be run.

Results and Discussion
  Method  624  is acceptable  for the
analysis of purgeable priority pollutants.
The accuracy of the method is judged very
good while overall precision and single-
analyst precision are considered accept-
able. For most compounds,  matrix does
not significantly  affect the analysis.
Method 624 was characterized in terms
of accuracy, overall precision, single-
analyst precision, and the effect of water
type on accuracy and precision through
statistical analyses of 9,880 reported
values.  Estimates of accuracy and
precision were made and expressed as
regression equations, shown in  Table 1
for each compound. The equations were
based on the 8,446 data values remaining
after eliminating 1,434 values (approxi-
mately 15%) designated as outliers by the •
IMVS programs. The  development and
interpretation of these regression equa-
tions  are discussed in Section 5. To
facilitate the interpretation of these
equations. Table 2 was prepared. In Table
2, accuracy (percent  recovery), overall
precision (percent standard deviation),
and  single-analyst precision (percent
standard deviation)  were computed
(using  the regression equations)  at a
concentration of 100 fjg/L.
  Accuracy is obtained by comparing
the mean recovery to the prepared values
of the concentrations and computing the
percent recovery. Overall, recoveries for
the volatile organic compounds are very
good for all of the water matrices with an
average  recovery  of 100%. The  mean
recovery statistics  (at  100 /ug/L) for the
volatile  organic compounds range from
68% fo'r bromomethane in the surface
water matrix to 123% for cis-1,3-
dichloropropene  in the distilled water.
One-half of the mean recoveries are
between 94% and 105%, with one-fourth
of the mean recoveries above and below
these values. Recoveries for bromometh-
ane are  consistently low (ranging from
68% to 75%) for all water matrices. Mean
recoveries for cis-1,3-dichloropropene
and  1,2-dichloropropane are high  with
recoveries ranging from 116% to 123%,
while the recovery of trans  1,3-dichloro-
propene is uniformly low, averaging 83%.
It is known that  the  isomers of 1,3-
dichloropropene are relatively unstable

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Tablt 1 . Regression Equations for Accuracy and Precision
Water Type Benzene Bromodichloromethane
Applicable Cone. Range
Distilled Water
Single-Analyst Precision
Overall Precision
Accuracy
Tap Water
Single-Analyst Precision
Overall Precision
Accuracy
Surface Water
Single-Analyst Precision
Overall Precision
Accuracy
Industrial Effluent
Single-Analyst Precision
Overall Precision
Accuracy
(10.8 - 480.01
SR = 0.26X- 1.74
S =0.25X- 1.33
X = 0.930 + 2.00
SR = 0.20X - 0.24
S =0.22X-0,75
X = 0.9SC + 1.40
SR = 0.15X-0.60
S =0.23X- 1.02
X = 0.94C + 1.88
SR = 0. 14X - 0.91
S = 0.22X-0.86
X = O.S9C + 1.60
(8.0 - 480.0)
SR = 0.1 5X + 0.59
5 = 0.20X + 1. 13
X = 1.03C - 1.58
SR = 0.17X + 0.94
S = 0.20X + 3.76
X - 1.03C + 1.35
SR = 0. 18X + 0.43
S = 0.22X + 0.80
X = 1.00C - 1.02
SR = 0.23X-0.15
S = O.22X+1.01
X =0.940-0.93
Bromoform*
(9.0 - 400.0)
SR = 0.14X + 0.19
S = 0.20X + /. 18
X = 1.01C - 0.89
SR = 0.31 X + 1.36
S = 0.33X + 1.03
X =1. 13C - 1.07
SR = 0. 18X + 0.06
5 = 0.26X + 0.98
X =0.57C-0.67
SH = 0.28X - 0.02
5 = O.33 + 0.49
X = 0.95C - 1.65
Bromomethane
(9. 1 - 6O7.O)
SR = 0.27X - 0.50
S = 0.25X + 0.64
X =0.720-0.79
SR=0.29X -0.45
S = 0.34X + 0.57
X =0.690 - 1.14
SR=0.24X -0.15
S = 0.25X + 0.67
X =0.690-0.51
SR=0.37X -0.21
S = 0.41 X- 0.07
X =0.760-0.80
X = Mean Recovery
C = True Value for the Concentration
'Revised regression equations and estimates of accuracy and precision are given in Table 2
Water Type
Applicable Cone. Range
Distilled Water
Single-Analyst Precision
Overall Precision
Accuracy
Tap Water
Single-Analyst Precision
Overall Precision
Accuracy
Surface Water
Single-Analyst Precision
Overall Precision
Accuracy
Industrial Effluent
Single-Analyst Precision
Overall Precision
Accuracy
Carbon Tetrachloride*
(9.0 - 400.0)
SR = 0.11X^0.35
S = 0.14X + 0.17
X = 1.01C - 0.84
SR = 0.23X - 0.85
S = 0.24X - 0.87
X = 1.070 - 1.66
SR = 0. 16X + 0.98
S =0.19X^0.95
X = 1.010 - 0.22
SR = 0.20X - 0.29
S =0.20X^0.54
X =0.950-0.62
Chlorobenzane
(13.5 - 600.0;
Sfl = 0.;6X-0.09
S =0.26X-1.92
X =0.980 + 2.28
SR = 0.1 9X + 0.69
S = 0.22X - 0.30
X = 1.020 + 2.04
SR = 0.19X-0.81
S =0.29X-2.60
X =1.010 + 2.91
SR = 0.23X + 0. 13
S = 0.36X - 2.20
X =0.920 + 2.36
Chloroethane*
(7.3 - 488.0)
SR = 0.23X + 2.02
S =0.27X+1.95
X = 1.080 + 1.50
SR = 0.31 X- 0.71
S = 0.35X + 0.04
X =1.100 + 0.13
SR = 0.22X+ 1.63
S =0.28X+1.47
X = 1.090 + 1.83
SR = 0.32X + 0.25
S =0.38X-0.21
X =1. 120 + 0.44
Chloroform
(4.5 - 300.0)
SR=0.16X + 0.22
s =0. isx + o. re
X =0.930 + 0.33
SR = 0.23X + 0.42
S = 0.31 X + 5.58
X =0.870 + 5.78
SR = O.22X - 0.30
S =O.23X-0.08
X =0.910 + 0.65
SR=0.14X + 0.33
S =0.18X + 0.65
X =0.940 + 0.37
X = Mean Recovery
C = True Value for the Concentration
"Revised regression equations and estimates of accuracy and precision are given in Table 2.
Water Type
                           Chloromethane*
                                CIS-1,3,-Dichloropropene
                                                              Dibromochloromethane
                                                           Ethyl Benzene
Applicable Cone. Range
Distilled Water
Single-Analyst Precision
Overall Precision
Accuracy
Tap Water
Single-Analyst Precision
Overall Precision
Accuracy
Surface Water
Single-Analyst Precision
Overall Precision
Accuracy
Industrial Effluent
Single-Analyst Precision
Overall Precision
Accuracy
(7.O - 469.0)


SR = 0.41X+ 1.75
S   =0.48X+1.21
X   =0.940 + 2.37


SR = 0.43X + 0.09
S   = 0.45X - 0.21
X   =O.O9C + O.20


SR = 0.37X - 0.46
S   =0.45X + 0.55
X   =1.120 - 0.56


SR = 0.59X -  1.33
S   =0.61X- 1.10
X   = 1.020 - 0.38
(8.0 - 357.0)


SR = 0.19X +0.44
S   = 0.24X + 0.07
X   =  1.240 - 0.55


SR = 0.21 X +0.38
S   = 0.27X + 0.55
X   =  1.210 - 0.47


SR = 0.26X - 0.90
S   =0.32X-0.33
X   =1.160 + 0.18


SR = 0.15X +0.33
S   =0.25X + 0.01
X   =  1.20C - 0.44
(8.1 - 360.0)


SR = 0.17X-0.18
S  =0.17X + 0.49
X  =1.010-0.03


SR = 0.23X - 0.24
S  = 0.26X + 0.88
X  = 1.070 - 0.44


SR = 0.20X -0.39
S  = 0.21 X - 0.18
X  =1,010 + 0.10


SR = O.I8X-0.38
S  = 0.26X - 0.87
X  = 1.070 - 0.70
(15.O - 68O.O)


SR = 0.14X + 1.00
S  =O.26X- 1.72
X  = 0.98C + 2.48


SR = 0.22X + 0.90
S  =O.24X-0.77
X  =0.990 + 2.97


SR = 0.15X + 0.38
S  =0.22X-1.25
X  = 1.010 + 3.88


SR=0.24X + 0.03
S  =0.29X- 1.27
X  =1.010 + 3.73
X = Mean Recovery
C = True Value for the Concentration
^Revised regression equations and estimates of accuracy and precision are given in Table 2

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Table 1 (continued)
Water Type
                           Methylene Chloride'"
                                                            Tetrach/oroethene
                                                                                         Toluene
                                                                                                                       Trans- 1 ,2-Dichloroethene*
Applicable Cone. Range
Distilled Water
Single-Analyst Precision
Overall Precision
Accuracy

Tap Water
Single-Analyst Precision
Overall Precision
Accuracy

Surface Water
Single-Analyst Precision
Overall Precision
Accuracy

Industrial Effluent
Single-Analyst Precision
Overall Precision
Accuracy
                           (7.2 - 480.0)


                           SR = 0.19X+0.76
                           S =0.30X+4.09
                           X =0.810 + 2.31


                           SR = 0.26X+ 5.78
                           S =0.36X+5.37
                           X =0.730 + 5.97


                           SR = 0.16X+9.45
                           S =0.25X+7.91
                           X = 0.800 + 8.57


                           SR = 0.30X + 3.54
                           S =0.44X+ 1.94
                           X =0.710+3.15
(9.0 - 400.0)


SR = 0,13X -0.18
S  = 0.16X-0.45
X  = 1.060 + 0.60


SR = 0.23X + 0.04
S  = 0.27X-0.64
X  =0.980 + 0.71


SR = 0.18X -0.22
S  = 0.25X - 1.16
X  = 1.020 + 1.54


SR = 0.27X + 0.54
S  = 0.31X - 0.15
X  =0.870+1.62
(13.5 - 600.O)

SR = 0.15X- 0.71
S  =0.22X- 1.71
X  = 0.980 + 2.03


SR = 0.18 + 0.71
S  =0.24X-0.66
X  =0.980 + 2.76


SR = 0.15X - 0.03
S  =0.23X- 1.67
X  = 1.000 + 2.25


SR = 0.22X - 0.93
S  =026X- 1.07
X  =0.920 + 2.63
(4.5 - 300.0)


SR = 0.16X + 0.03
S  =0.19X + 0.13
X  =0.980 + 0.30


SR = 0.17X +0.20
S  =0.17X + 0.52
X  =1.050-0.17


SR = 0.16X + 0.10
S  =0.16X + 0.37
X  =0.980 + 0.26


SR =0.21 X -0.09
S  =0.23X + 0.07
X  =0.960 + 002
X = Mean Recovery
C = True Value for the Concentration
"Revised regression equations and estimates of accuracy and precision are given in Table 2
Water Type
Applicable Cone. Range
Distilled Water
Single-Analyst Precision
Overall Precision
Accuracy
Tap Water
Single-Analyst Precision
Overall Precision
Accuracy
Surface Water
Single-Analyst Precision
Overall Precision
Accuracy
Industrial Effluent
Single-Analyst Precision
Overall Precision
Accuracy
Trans-1,3-Dichloropropene
(9.4 -416.0)
SR = 0.20X - 0.53
S = 0.26X - 0.09
X = 0.800 + 0.22
SR = 0, 13X + 0.94
S = 0.25X + 0.23
X = 0.830 - 0.58
SR = 0. 15X + 0.03
S =0.24X + 0.18
X =0.890 + 0.69
SR = 0.18X -O.37
S =0.22X-0.48
X = 0.820 - 0.08
Trichloroethene
(5.4 - 360.0)
SR = 0.1 3X + 0.36
S = 0.1 2X + 0.59
X = 1.040 + 2.27
SR = 0.23X - 0.34
S =026X-0.28
X = 1.030 + 1.65
SR = 0. 14X + 1.05
S = 0.1 9X-+ 0.94
X = 1.030 + 2.91
SR = 0.22X + 0.75
S = 0.33X - 0.03
X =0.990 + 1.76
Trichlorofluoromethane"
(7.2 - 480.0)
SR = 0.31X- 1.34
S = 0.36X - 0.48
X = 0.920 + 0.83
SR = 0.18X + 0.66
S =0.31X-015
X = 0.980 + 0.34
SR = 0.28X - 0.30
S = 0.31 X + 0.02
X =0.850 + 0.70
SR = 0.24X - 1.36
S =0.28X-0.56
X = 1.OOC + 0.25
1. 1 -Dich/oroethane"
(10.8 - 480.0)
SR = 0. 15X - 0.22
S =0. 15X + 0.53
X =0.980 + 1.09
SR =0.16X -0.21
S =0.14X + 0.82
X =1.010 + 0.11
SR= 0.1 IX +1.07
S =0.12X+1.06
X =0.990+1.13
SR = 0.23X - 0.27
S = 0.24X + 0.84
X = 1.040 + 0.39
X = Mean Recovery
C = True Value for the Concentration
"Revised regression equations and estimates of accuracy and precision are given in Table 2
Water Type
Applicable Cone. Range
Distilled Water
Single-Analyst Precision
Overall Precision
Accuracy
Tap Water
Single-Analyst Precision
Overall Precision
Accuracy
Surface Water
Single-Analyst Precision
Overall Precision
Accuracy
Industrial Effluent
Single-Analyst Precision
Overall Precision
A ccuracy
1, 1 -Dichloroethene"
(7.2 - 480.0)
SR = 0.22X + 0.58
S = 0.37X + O.24
X = 1.010 + 1.43
SR = 0.16X+ 1.73
S =0.23X + 0.60
X = 0,940 + 2.07
SR = 0. 14X + 0.95
S - 0.21 X + 0.69
X =0.950 + 1.38
SR = 0.23X - 0.35
S = 0.23X + O.24
X =0.840+1.57
1, 1, 1 -Trichloroethane
(9.0-4000)
SR = 0. 12X - 0. 15
S = 0.21 X- 0.39
X =1.060 + 0.73
SR = 0.20X - 0.54
S =0.23X-0.22
X =1.110-0.53
SR = 0.23X - 0.27
S =0.28X-0.82
X =1.010 + 0.31
SR = 0. 18X - 0.81
S = 0.24X - 0.55
X =0.990 + 0.83
1, 1 ,2-Trichloroethane
(10.8 - 480.0)
SR = 0. 14X + O.02
S =0.18X + O.OO
X =0.950+1.71
SR = 0,12X+ 1.44
S = 0.15X + 0.74
X = 1.020 + 1.80
SR = 0.1 6X -0.27
S = 0.21 X - 0.84
X = 1.040 + 1.55
SR = 0.18X + O.05
S = 0.23X - 1.06
X = 1 000 + 1.04
1. 1,2.2-Tetrachloroethane
(15.O - 680.0)
SR=0.16X + 0.69
S =0.20X + 0.41
X =0.930+1.76
SR = 0. 16X + 0.30
S =0.25X-0.83
X = 0.920 + 0.94
SR = 0 14X+ 1.08
S = 0.20X + 1.53
X = 0.990 + 1.45
SR = 0.37X - 1.22
S =030X + 0.91
X =0.870+2.09
 X = Mean Recovery
 C = True Value for the Concentration
 "Revised regression equations and estimates of accuracy and precision are given in Table 2
                                             4

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Tahiti, (Continued/

Water Type 1,2-Dichlorobenzene/1,4-D 1,2-Dichloroethane
Applicable Cone. Range (16.O - 780.O)
Distilled Water
Single-Analyst Precision SR = 0.22X - 1.45
Overall Precision S -0.3OX-1.20
Accuracy X = 0.94C + 4.47
Tap Water
Single-Analyst Precision SR = 0.36X - 2.57
Overall Precision S -0.38X-1.56
Accuracy X = 0.98C+4.65
Surface Water
Single-Analyst Precision SR - 0.25X + 0.85
Overall Precision S = 0.30X + 1.48
Accuracy X = 0.97C + 6.92
Industrial Effluent
Single-Analyst Precision SR = Q.25X + 2.55
Overall Precision S = 0.29X + 4.32
Accuracy X =0.95C + 5.14
X = Mean Recovery
C = True Value for the Concentration
Table 2. Revised Regression Equations
Water Type
Applicable Cone. Range lug/L)
Distilled
Single-Analyst Precision
Overall Precision
Accuracy
Tap Water
Single-Analyst Precision
Overall Precision
Accuracy
Surface Water
Single-Analyst Precision
Overall Precision
Accuracy
Industrial Effluent
Single-Analyst Precision
Overall Precision
Accuracy
(9.9 - 440.0)
SR = 0.17X -0.32
S = 0.21X-0.38
X = 1.02C + 0.45
SR = 0.18X-0.21
S = 0.17X^0.14
X = 1.06C • 0.45
SR = 0. 15X + 1.01
S = 0.18X+1.69
X =1. 01C + 0.97
SR = 0. 14X + O.96
S = 0.18X+1.44
X = 1.01C • 0.28

lor Accuracy and Precision
Bromoform
(9.0 - 400)
SR = 0. 12X + 0.36
S = 0.17X+1.38
X =1. 18C - 2.35
SR = 0.23X + 2.06
S = 0.33X+1.01
X =1.320-2.74
SR = 0.1 4X + 0.38
S = 0.24X + 1.08
X = 1.10C- 1.80
SR = 0.18X + 0,65
S = 0.25X + 1.02
X = 1.06C - 2.67

1 ,2-Dichloropropane
(13.5 - 600.0>
SR = 0. 14X - 0.85
S = 0.17X-0.41
X = 1. 18C + 2.00
SR=0.10X + 0.95
S = 0. 13X + 0.53
X =1.16C+1.70
SR = 0.13X-0.52
S = 0.17X-O.33
X =1.18C + 2.89
SR = 0. 13X + 0.77
S =0. 18X + 0.53
X = 1.22C - 0.25


Carbon Tetrachloride
(9.0 - 400)
SR - 0. 12X + 0.25
S =0.1 IX + 0.37
X =1.100+1.68
SR = 0. 18X - 0.53
S =0.20X-0.61
X =1.180-2.66
SR = 0. 15X + 7.07
S =0.18X + 0.98
X =1.070-0.73
SR = 0. 19X - 0.23
S =0. 19X + 0.59
X = 1.OOC - 1.07

1. 3-Dichlorobemene
(7.2 - 480.0)
SR=0.14X-0.48
S = 0.1 8X- 0.82
X = 1.06C + 1.68
SR = 0.22X + 3.41
S = 0.24X + 2.34
X = 1.02C + 3.80
SR=0.15X + 1.44
S = 0.16X^1.72
X =1.1 1C + 1.90
SR = 0. 15X + 2.01
S = 0.17X^1.83
X =1.030 + 1.79


Chloroethane
(7.3 - 488)
SR=0.14X+2.78
S =0.29X+1.75
X =1.180 + 0.81
SR = 0.29X - 0.52
S = 0.34X + 0. 13
X =1.170-0.37
SR=O.25X+ 1.37
S = 0.28X + 1.46
X =1.120+1.63
SR = 0.32X + 0.25
S = 0.4OX - 0.37
X = 1.240 - 0.41
X = Mean Recovery
C = Prepared Concentration
Water Type
Chloromethane
                                  Methylene Chloride
                                Trans-1,2-Dichloroethene
Applicable Cone. Range fag/L)

Distilled
Single-Analyst Precision
Overall Precision
Accuracy

Tap Water
Single-Analyst Precision
Overall Precision
Accuracy

Surface Water
Single-Analyst Precision
Overall Precision
Accuracy
(7.0 - 469)
SR = 0.37X + 2.14
S  =0.58X + 0.43
X  = 1.030 + 1.81
SR = 0.38X + 0.40
S  =0.55X-0.79
X  =0.960-0.20
SR = 0.32X - 0.05
S  =0.49X + 0.27
X  = 1.230 - 1.31
(7.2 - 480)
SR = 0.15X + 1.07
S  =0.32X + 4.OO
X  =0.870+1.88
SR = 0.2OX + 4.96
S  =0.38X + 5.19
X  =0.780 + 5.66
SR=0.27X + 8.17
S  =0.29X+7.48
X  = 0.830 + 8.40
(4.5 - 3OO)
SR = 0.14X + 0.09
S  =0.19X + 0.17
X  = 1. ISO + O.03
SR= 0.1 IX + 0.49
S  =0.15X + 0.60
X  =1.110-0.40
SR=0.17X
S  =O.15X + 0.4O
X  = 1.020 + 0.05

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Table 2,    (continued)
Water Type
Chloromethane
Methylene Chloride
Trans-1,2-Dichloroethene
Industrial Effluent
Single-Analyst Precision
Overall Precision
Accuracy
SR = 0.61X- 1.43
S  =0.58X-0.95
X  = /. J3C - 1.23
SR = 0.30X + 3.56
S  = 0.42X + 2.06
X  =0.800 + 2.50
SR = 0.26X - 0.29
S  = 0.19X + 0.22
X  = 1.02C - 0.23
X = Mean Recovery
C = Prepared Concentration
Table 2.   (continued)

Water Type
Trichlorofluoromethane
1,1 -Dichloroethane
1.1 -Dichloroethene
Applicable Cone. Range (fjg/L)

Distilled
Single-Analyst Precision
Overall Precision
Accuracy

Tap Water
Single-Analyst Precision
Overall Precision
Accuracy

Surface Water
Single-Analyst Precision
Overall Precision
Accuracy

Industrial Effluent
Single-Analyst Precision
Overall Precision
Accuracy
(7.2 - 480)
SR-0.33X- 1.48
S  = 0.34X-0.39
X  = 0.990 + 0.39
SR = 0.17X + O.80
S  = 0.29X + O.04
X  =1.050-0.19
SR = 0.33X -0.57
S  = 0.31 X + 0.03
X  =0.870 + 0.50
SR = 0.27X + 1.62
S  =0.26X-0.43
X  = 1.070 - 0.29
(10.8 - 480)
SR = 0.13X - 0.05
S  = 0.16X + 0.47
X  = 1.05C + 0.36
SR = 0.14X - 0.08
S  =0.14X + 0.52
X  = 1.070 - 0.53
SR = 0.11X + 1.08
S  = 0.12X+1.12
X  =1.020 + 0.76
SR = 0.23X -0.27
S  = 0.21 X+ 1.12
X  =1.090-0.12
(7.2 - 480)
SR=0.17X+ 1.06
S  =0.43X-0.22
X  = 1.120 + 0.61
SR = 0.12X + 2.08
S  =0.24X + 0.53
X  = 1.020 + 1.43
SR=0.16X + 0.87
S  =0.24X + 0.51
X  =1.010 + 0.91
SR = 0.24X - 0.39
S  = 0.20X + 0.39
X  = 0.930 + 0.94
X = Mean Recovery
C = Prepared Concentration

and may decompose to 1,2-dichloropro-
pane.
  The  overall standard deviation of the
analytical results is an indication of the
precision associated with the measure-
ment generated by a group of laboratories.
The percent relative standard deviation
(RSD) at 100 /t/g/L for the volatile organic
compounds range from 13% for trichloro-
ethene,  1,1-dichloroethane, and  1,2-
dichloropropane  in  the various water
matrices to 60% for Chloromethane in the
industrial effluent with a median value of
24%. Precision for Chloromethane is
relatively poor for all water matrices with
percent  relative standard  deviations
ranging from 45% to 60%. One-half of the
RSDs are between 20% and 29%. In 95%
of the cases the RSDs are less than 44%.
  The percent relative standard deviation
for a single analyst  (RSD-SA) indicates
the precision associated within a single
laboratory. The RSD-SA for samples at
100 /ug/L  ranges from 11 % for carbon
tetrachloride (distilled water matrix) and
1,2-dichloropropane (tap water matrix) to
58% for Chloromethane in  the industrial
effluent with a  median RSD-SA of 19%.
Single-analyst precision for Chlorometh-
ane is relatively poor with RSD-SAs
    ranging from 37% to 58%. One-half of the
    RSD-SAs at 100 /jg/L are between  15%
    and 23%. In 95% of the cases, the RSD-
    SAs are less than 36%. Three compounds
    used  in  this  study, bromomethane,
    Chloromethane and  chloroethane, are
    gases in pure form. Although there are no
    clear trends for accuracy in the gaseous
    species  as opposed to less volatile
    compounds, it is  possible  that the low
    recovery observed for bromomethane
    and the  poor precision for all three
    compounds may be due  to inherent
    difficulties in  handling gaseous  and
    extremely volatile compounds during the
    various preparation and analytical proce-
    dures required in the method.  Bromo-
    methane is also known to  be unstable,
    which could also account for low recover-
    ies.
      The effect of water type was different
    for the various volatile organic compounds.
    For most compounds the  water matrix
    does not have a great effect on either the
    accuracy or precision. Overall, recoveries
    for the volatile  organic  compounds
    averaged 100% in distilled water, 101%
    in tap water and surface water, and 97%
    in the industrial effluent matrix. Precision
    (RSD and RSD-SA) for the volatile organic
             compounds ranged from a median RSD of
             21% and median RSD-SA of 16% for the
             distilled water to a median RSD of 25%
             and  a median RSD-SA of 23% for the
             industrial effluent matrix.
               A  trend toward higher recoveries
             (above 100%) forthe lowest concentration
             Youden  pairs was observed for  10
             compounds. One explanation  could  be
             sample contamination from the presence
             of these compounds in the laboratory.
             Methylene chloride displayed  the  most
             pronounced example  with recoveries
             averaging 142%, 76%  and 83%  for the
             low, medium and high pairs respectively.
             Low-level contamination may be respon-
             sible for the 142% recovery of the low
             pair. Blank concentrations were also
             higher for  methylene chloride than  for
             many of the other compounds, indicating
             a greater likelihood of  low-level sample
             contamination. This explanation  is less
             clear for other compounds. For example,
             the  trend is more pronounced for the
             chlorobenzenes than  for benzene  or
             chloroform, yet the latter compounds
             would be expected  to be more ubiquitous
             in a  laboratory environment.
               A review of the data remaining after the
             IMVS  outlier screening indicated some

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potential problems with the data for nine
of the volatile organic compounds. For
these compounds, results for ampul four
were out-of-line (usually due to extremely
low recoveries) with the remaining data.
It is suspected that during production of
ampul concentrate four, these volatile
compounds were lost. The data for these
medium level ampuls were eliminated,
and  the equations  revised.  Table 2
presents the revised equations.
  Four compounds in addition to those
listed  in  Table 2 had questionable
regression equations although the equa-
tions  were  not  revised. These were
bromomethane, cis and trans  1,3-
dichloropropene and 1,2-dichloropropane.
Bromomethane exhibited poor recoveries
which may have been due to its extreme
volatility or to its reactivity. The dichloro-
propenes are known to be unstable and to
form dichloropropane upon decomposi-
tion.  Problems with  these compounds
were also encountered with USEPA
Quality Control  Samples  and  in the
Interlaboratory Study for Method 601 —
Halogenated Purgeables by GC.
This Project Summary was authored by staff of Radian Corporation, P. 0. Box
  9948. Austin. JX 78766
Raymond Wesselman and Bob Graves are the EPA Project Officers (see below).
The complete report, entitled "EPA Method Study 29, Method 624—Purgeables,"
  (Order No. PB 84-209 915; Cost: $20.50, subject to change) will be available
  only from:
       National Technical Information Service
       5285 Port Royal Road
       Springfield, VA22161
       Telephone: 703-487-4650
The EPA Project Officers can be contacted at:
       Environmental Monitoring and Support Laboratory
       U.S. Environmental Protection Agency
       Cincinnati, OH 45268
                                                                                        *USGPO:  1984-759-102-10632

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Environmental Protection
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