United States
Environmental Protection
Agency
Environmental Monitoring
Systems Laboratory
Las Vegas NV89114
Research and Development
EPA-600/S4-84-027 June 1984
^EPA Project Summary
Inter laboratory Comparison
Study: Methods for Volatile and
Semivolatile Compounds
Donald F. Gurka
A program is underway within the
U.S. Environmental Protection Agency
(EPA) to improve the reliability of its
analytical methods. As part of this
program, test protocols for the deter-
mination of volatile and semivolatile
organic compounds in hazardous wastes
were developed and subjected to a nine-
laboratory intercomparison study. Vola-
tileswere determined by the purge-and-
trap gas chromatography/mass spec-
trometry (GC/MS) analysis of a tetra-
glyme extract. Semivolatiles were
determined by fused silica capillary
column (FSCC) GC/MS analysis of a
methylene chloride extract obtained
from a neutralized dried sample. Detailed
quality assurance/quality control (QA/
QC) guidelines were provided to each
laboratory. Seven waste samples and
one standard reference material (SRM)
were each analyzed in triplicate by
GC/MS for a target list of 200 com-
pounds, including 45 sample spikes.
The protocols were shown to work best
for the less polar aprotic compounds.
The between-laboratory analytical
precision component for both volatiles
and semivolatiles was approximately
twice that of the within-laboratory
component. The effect of excluding
outlier data on precision calculations is
dramatically illustrated on analytical
data derived from a standard reference
material.
This Project Summary was developed
by EPA's Environmental Monitoring
Systems Laboratory. Las Vegas, NV. 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 U.S. Environmental Protection
Agency (EPA) is currently involved in a
broad program to assess and improve the
reliability of the data generated using
recommended hazardous waste analyti-
cal protocols. This program is essential to
maintain the credibility of the EPA as a
regulatory agency. Included in this broad
program is the submission of those
analytical protocols in widest usage to
interlaboratory comparison testing. Such
interlaboratory comparison testing is one
of the most important elements of any
methods validation plan. Although sub-
stantial expenditure of both time and
money is required, multi-laboratory
testing of many EPA methods is currently
underway. The full report describes the
evaluation of analytical protocols for the
determination of volatile (boiling up to ca.
200°C) and semivolatile compounds
(boiling up to ca. 500°C) in hazardous
wastes by an interlaboratory comparison
test.
The workplan for this project consisted
of three distinct phases:
1. Selection, evaluation and optimiza-
tion of the best available methods for
determining volatile and semivolatile
organic compounds in solid wastes.
2. Rigorous single laboratory evaluation
of the optimized methods and method
revision where necessary. Prepara-
tion of all materials for distribution to
the participating laboratories. Peer
review of the selected methods.
3. Interlaboratory comparison testing.
The guiding workplan philosophy was to
severely challenge the selected methods.
Thus, the target analytes and sample
matrices were selected to represent a
broad spectrum of hazardous waste
-------
analytical situations. In addition, each
waste sample contained significant
quantities of endogenous compounds.
This ensured the presence of background
interference problems and provided a
"real world" matrix background for the
spike compounds.
Two analytical test procedures were
evaluated in the interlaboratory study.
One of the procedures was a GC/MS
analysis procedure for the determination
of volatile organic compounds. This
procedure involved the extraction of a
waste sample with tetraethyleneglycol
dimethyl ether (tetraglyme), the addition
of a portion of the extract to reagent
water, and analysis according to the
purge-and-trap technique of EPA Test
Method 624. The other method, a
GC/MS analysis method for the determi-
nation of semivolatile organic compounds,
involved the methylene chloride extraction
of a waste sample by sonification under
neutral anhydrous conditions and analysis
of the extract using a fused silica capillary
column.
Experimental Section
Preparation of Calibration
Solutions
All standard solutions required for the
interlaboratory comparison study were
purchased or prepared in sealed glass
ampoules and distributed to the partici-
pating laboratories. The standards included
calibration solutions, surrogate recovery
solutions, and internal standard solutions.
The standard solutions distributed for the
determination of volatile compounds
included six calibration solutions contain-
ing a total of 53 representative volatile
compounds, a surrogate solution contain-
ing four fluorinated compounds as recovery
standards, and an internal standard
solution .containing p-bromofluoroben-
zene (BFB) as a mass spectrometer tuning
standard and three deuterated internal
standards. The standard solutions distri-
buted for the determination of semi-
volatile compounds included four calibra-
tion solutions containing a total of 140
representative semivolatile compounds,
a surrogate solution containing three
fluorinated recovery standards, an inter-
nal standard solution containing decaflu-
orotriphenylphosphine (DFTPP) as a mass
spectrometer tuning standard, 12 deuter-
ated internal standards and GC/MS
performance standards.
Preparation of Spiked Wastes
The wastes used in the study (Table 1)
were selected to challenge the sample
Table 1. Interlaboratory Comparison Samples
Sample
Number
2
3
4
5
6
7
8
9
Waste Name
Spiked latex paint waste
Spiked ethanes spent catalyst
Spiked coal gasification tar
Spiked oxych/orination spent catalyst
Spiked POTW sludge
Spiked herbicide acetone-water
Spiked chlorinated ethanes waste
Contaminated river sediment fJS/7/W]
Physical
Description
Semi-so/id
Oily powder
Tar
Pellet/zed solid
Wet filter cake
Liquid
Liquid
Oily powder
Analyses
Performed*
s.v
S.V
S.V
S.V
S.V
V
V
S
"S = determination of semivolatile compounds.
V - determination of volatile compounds.
workup procedure and to represent a
broad range of waste types. These wastes
were shown to contain a significant
number of naturally incorporated com-
pounds, and were available in sufficient
quantities for a multi-laboratory study.
The wastes were spiked with the repre-
sentative volatile and semivolatile com-
pounds, these spike concentrations were
chosen to be similar to the levels of other
volatile and semivolatile components
present in the unspiked wastes. Prelimi-
nary screening was used to show that
most of the spike compounds were
different from those naturally incorporated
within the unspiked wastes.
To reduce analytical costs, a spiking
scheme was devised to minimize the
number of GC/MS analyses required for
each waste. The scheme involved spiking
each waste with pairs of chemically
compatible compounds. The two com-
pounds in each pair were selected on the
basis of similar properties (volatility,
solubility, polarity, or acidity) that would
be expected to provide similar recovery
efficiencies. A previous intralaboratory
study had demonstrated that the two
compounds in each pair did yield com-
parable recoveries. One compound from
each pair was, spiked at a relatively low
level and the other at an approximately
five-fold higher level. With this approach,
analytical data, for naturally incorporated
components and recovery data for
different classes of compounds at two
spike levels, were obtained simultane-
ously in a single GC/MS run.
The high and low spike levels used
corresponded to those levels that would
give approximately 50 ng and 250 ng of
volatile compounds or 10 ng and 50 ng of
semivolatile compounds on the GC
column during analysis if 100% extraction
recovery were achieved. Since the degree
of dilution or concentration required for
each extract varied widely from waste to
waste, the actual spike level used also
varied widely from waste to waste.
Design of Collaborative Test
Each participating laboratory was sent
detailed descriptions of the analysis
protocols, ampoules of the standard
solutions, samples of the seven spiked
wastes and a sample of NBS Standard
Reference Material No. 1645. The
standard reference material, a contami-
nated river sediment, was included to
obtain reference data for future work.
Each laboratory was requested to analyze
three replicates of each spiked waste to
determine volatile compounds and three
replicates of five of the spiked wastes and
the standard reference material for
semivolatile compounds. The laboratories
were requested to search for 53 specific
volatile compounds and 140 specific
semivolatile compounds, and to quantify
the amounts of any of the compounds
found. These compounds, which include
both spike compounds and naturally
incorporated compounds, were selected
as representative of various classes of
compounds to challenge the method and
assess its broad applicability. In addition,
the laboratories were requested to report
and quantify up to 10 major unlisted
compounds found in each sample.
Statistical Design
The data reported by the laboratories
participating in this collaborative study
include the amount of compound found
(AF) in the sample, the response factor
(RF) and the retention time(RT) or relative
retention time (RRT). These data were
reported by nine laboratories for 53
volatile compounds in each of seven
sample types, and for 140 semivolatile
compounds in each of six sample types.
Since each of the nine laboratories
conducted three replicate analyses, there
were potentially 27 values to be reported
for each compound in each sample type.
However, due to various causes, data were
not always reported for each replication.
-------
The percent of compound recovered by
each laboratory was calculated by
I AF „
% Recovery = '- J x 1 nn
IAF+SLQ
where IAF is the initial amount-found in
the sample by intralaboratory analysis,
and SLQ is the spike level quantity. The
summation is taken over all AF data
reported. The percent of AF data reported
was calculated by dividing the number of
data reported by 27, the maximum total
number of available data points.
For each combination of sample type
and compound, the data were analyzed
using the random componentsanalysis of
variance model
Amount-Foundi, (AFij) = fj + U + dj
i = 1,2 ..... 9 j = 1,2,3
where AFij is the amount of compound
found on the j'h replication by the ith
laboratory. U is the random systematic
error due to laboratory i and E\\ is the
random within-laboratory error. It is
assumed that Li is distributed normally
with mean zero and variance crl2. The
within-laboratory error term, Cij, is
assumed to be normally distributed with
mean zero and variance af.
The total variance for the AF data is
given by:
-------
GC/MS response factor performance
criteria to be recommended for the
interlaboratory comparison study. A list
of 20 response factors was prepared, and
a response factor precision of ±40
percent was recommended to ensure
data quality. The recommended ±40
percent range was based on twice the
percent relative standard deviation (%
RSD) for compounds with % RSD up to 20
percent in order to provide at least a 95
percent confidence level.
Homogeneity Study
A study was undertaken to determine if
the spiked and naturally occurring com-
pounds were uniformly distributed among
the sample aliquots to be distributed to
the interlaboratory test participants.
Aliquots taken from replicate vials of the
homogenized spiked waste samples were
extracted following the test protocol
procedures. The extracts were analyzed
in duplicate by GC to quantify the GC-
resolvable components, and in triplicate
by a microcoulometric method to deter-
mine total purgeable organic halogen.
Analysis of variance treatment indicated
that the samples in the individual vials
were homogeneous within the precision of
the methods used, with the single excep-
tion of the semivolatile compounds
determined in sample number 6. The net
vial-to-vial variability of the compounds
in that sample was about 15 percent. The
study indicated that the spike compounds
were as homogeneously distributed with-
in each sample as the naturally incorpor-
ated compounds.
Recovery, Precision, and
Detectability of Volatile
Organics
The average percent recoveries and the
total between-laboratory and within-
laboratory relative standard deviations
for the'spiked and naturally incorporated
volatile compounds in the seven wastes
were determined. If data were reported
for fewer than 20 percent of the required
analytical runs the percent RSDs were
not determined. The variability of volatile
organics results exhibited a dependence
on sample matrix.
The within-laboratory variability for
analysis of volatiles was generally less
than 30 percent but ranged from 5 to 300
percent depending onthecompound.The
total variability generally ranged from 20
to 80 percent for most of the waste
samples. The between-laboratory varia-
bility was usually less than 70 percent
but ranged from 5 to 300 percent. The
highest variabilities, both total and
component, were reported for non-spike
compounds that are common background
contaminants such as methylene chloride,
dichloroethane, chloromethane, and
chloroform. Only in the case of sample 4
were high percent RSD's reported for
spiked compounds.
The effect of laboratory on detectability
of specific volatile compounds was
ascertained from the reported data.
Variability dependent on the laboratories
was evident and was not reproducible on
a per-sample basis, i.e., a certain
laboratory could report a larger number of
data for one sample than the other
laboratories and report the fewest
number for another sample.
Recovery, Precision and
Detectability of Semivolatile
Organics
The sample-to-sample variability noted
for the volatile compounds was also
evident for the semivolatile compound
analyses. The differences in amount of
data reported were greater for the
determination of semivolatiles than for
the determination of volatiles. For
example, for sample 3, the number of
compounds reported varied from 1 to 27,
with 20 being the average number of
compounds reported. The total RSD
generally ranged from 30 to 80 percent.
The RSD for the within-laboratory
component was less than 30 percent and
the between-laboratory variability was
about twice that value. The ranges of both
components were the same as those
reported for volatile organics, 5 to 300
percent. No difference in ranges of values
is apparent for the spiked versus non-
spiked compounds; however, some of the
poorer precision may be attributable to
polarity and to background contaminants,
such as phthalates.
Effect of Compound, Sample
and Spike Level on the
Detectability of Volatile and
Semivolatile Organics
A presentation of percent detection
data for each waste sample, arranged
according to specific compounds, is
provided in Table 2 for volatile compounds
and in Table 3 for semivolatile compounds.
These two tables provide information
regarding the effect of compound and
sample type on the method detection
capability. In addition, the data are
identified by either low spike level
(underlined values) or high spike level.
The average percentage of reported
compounds was higher for both volatile
and semivolatile compounds spiked at the
high level (73 and70 percent, respectively).
The low level spikes were reported 57
percent of the time for the determination
of volatiles and 47 percent for the
determination of semivolatiles. The more
difficult waste samples are also apparent
from these data, namely samples 5 and 6
for volatiles and samples 3, 5 and 6 for
semivolatiles analysis.
Total Volatile and Semivolatile
Organic Compounds Reported
It was instructive to examine the total
number of volatile and semivolatile
compounds reported by each laboratory
for each sample. Such an examination
could identify difficult samples and
differences in laboratory performance.
The two samples for which the poorest
VOA results were obtained were sample
3 (oxychlorination spent catalyst) and 6
(POTW sludge). These two solid sample
matrices might be the least retentive for
volatile compounds, and appreciable
amounts of the spike or naturally incor-
porated volatile components may have
been lost during sample storage. The best
results were obtained with samples 2, 3,
and 8 while 4 and 7 provided intermediate
results. The differences in laboratory
performance are more difficult to assess.
However, the VOA performance of
laboratory no. 8 was definitely poorer
than that of the other laboratories. The
poorest semivolatile results were reported
by laboratory no. 7 while the best
performance was noted for laboratory no.
2. The problem samples for semivolatile
determinations were samples 5 and 6,
closely followed by sample 3. The best
semivolatiles results were obtained for
samples 4 (except by laboratory no. 7) and
2. Laboratory no. 4 experienced consider-
able difficulty with sample 3 while
laboratory nos. 1 and 5 experienced
unusual detection problems with semi-
volatiles in sample 5.
Outlier Effect on Standard
Reference Material Results
The results of all reported data for the
National Bureau of Standards SRM were
surprisingly variable. The total variabilities
ranged from 28 to 338 percent and
averaged 160 percent. The quantities of
compounds reported were lower than
those of most of the other test samples,
however, the quantities of compounds
found in samples 5 and 6 were compara-
ble. The homogeneity of this sample
should be better than the other test
samples since NBS prepared this material.
-------
Table 2. Effect of Compound, Sample and Spike Level on Volatile Compound Detectability
r mnnunrl Percent of Data Reported for Given Sample3"
Average Percent
Number
12.
24.
25.
33.
44.
46.
47.
50.
51.
Compound
Propionitrile
2-Chloroa cry I on it rile
1, 1.1-Trichloroethane
1, 2-Dichloropropane
Bromoform
2-Hexanone
1, 1,2.2-Tetrachloro-
ethane
Chlorobenzene
Ethylbenzene
Average
2
11
100
100
100
100
89
89
96
100
87
3
0
96
93
96
85
52
93
96
96
79
4
22
4
78
100
56
37
67
100
89
61
5
11
11
11
56
67
11
100
89
41
44
6
0
4
7
48
4
26
4
WO
89
31
7
11
4
78
100
56
52
100
100
89
66
8
26
78
89
78
89
89
100
100
89
82
Lowc
4
24
65
75
67
38
62
97
77
57
High6
18
67
65
88
63
68
92
97
95
73
Total*
12
42
65
83
65
51
79
97
87
64
"The maximum number of analytical runs for which data could be reported for each sample was 27 (3 replicates x 9 laboratories).
ThB r»rr*nt nf ri*ta rvpnr,*^ total number of analytical runs for which data were reported\ 10Q
27
^Percent of data reported for compounds spiked at the low level are underlined.
^Average of the percents of data reported for samples in which the compound was spiked at the low level.
aAverage of the percents of data reported for samples in which the compound was spiked at the high level.
"Average of the percents of data reported for all samples.
A closer inspection of the data reported
revealed that most of the variability could
be attributed to outlier values reported by
one laboratory. In some cases a significant
portion of the variability was caused by
outlier values reported by a second
laboratory. The improvement in the total
variabilities obtained by omitting the data
from one laboratory or two laboratories in
the calculations are shown in Table 4. By
omitting the data from two laboratories
the total variabilities ranged from only 13
to 90 percent and averaged 31 percent.
An average total variability of 31 percent
for the analysis of complex sample is un-
expectedly good. The within-laboratory
component of the variability would be
much less. Amount-found values for 8 of
12 compounds reported in Set C of Table
4 are within a factor of 2.2 of the values
reported for this SRM in a previous study.
This is surprisingly good agreement for
the determination of naturally incorporated
compounds by two different analytical
methods. One of the four'compounds with
values outside the factor of 2.2 was
obtained for di-n-butyl phthalate, a com-
mon laboratory background contaminant.
Conclusions and
Recommendations
The non-aqueous neutral extraction
followed by fused silica capillary column
GC/MS analysis eliminates separate
acid/base extractions and reduces the
required number of GC/MS runs. The
analytical data reported for all samples
will be investigated in greater detail to
determine the causes of statistical
outliers. If these outliers result from
laboratory deviations from the test
Methods and quality control protocols
they can be excluded from the pooled
precision results. However, the validity of
discarding outlier results is still a subject
of disagreement among statisticians and
chemists. If outliers are shown to be a
result of protocol ambiguities, the
appropriate protocol sections should be
clarified. These steps may reduce the
number of outliers generated in future
applications of these methods. The
between-laboratory to within-laboratory
ratio of about two for the precision of
these test methods compares favorably
with the recently compiled results of over
fifty AOAC interlaboratory comparison
tests.
The wide variation in individual labora-
tory performance demonstrates the need
for strong QA/QC monitoring of labora-
tories performing routine environmental
analyses. Although each participating
laboratory had some prior experience
with the test protocols, it is anticipated
that further experience will lead to
improved analytical performance.
Further examination of the analytical
results and observations of the interla-
boratory comparison study for evaluation
of hazardous waste methodology will
significantly enhance the value of this
complex study. The volume of data
generated far exceeds data obtained for
any previous interlaboratory method
evaluation. The scope of the study thus
far included statistical evaluation of only
a small portion of this data base. In
addition, no provision was included for
statistical reanalysis excluding outlier
results. Based on the interpretation of the
analytical data the following specific
recommendations are presented:
O Expand the statistical treatmentof the
interlaboratory comparison data to
include analysis of data to identify
sources of observed variabilities.
O Repeat statistical analysis of percent
recovery data excluding obvious
outliers.
O Investigate sources of significant
data variability in the following
method steps:
1) Prescreening
2) Extraction (Investigate reasons for
the wide variation in extract
aliquot size chosen for GC/MS
analysis.)
3) Instrumental Analysis
4) Response factor determination
(Are anomalous GC/MS response
factors correlated?)
5) Confirmation of compound identi-
fication and quantification proce-
dures
6) Calculation
O Conduct interviews of participating
laboratories to evaluate interpretation
of instructions (both excellent and
poor performances would provide
valuable insight).
O Modify method instructions and
quality control protocols to eliminate
potential sources of analytical varia-
bility.
The completion of these recommended
tasks will result in a more thorough
evaluation of the data generated by this
collaborative study. It is anticipated that
the revised statistics will be significantly
improved, over those reported in this
study, in terms of precision and accuracy.
Further, the resulting revisions in descrip-
tion of the methods for volatile and
semivolatile organic analysis will result
in more uniform application of these
methods in the future.
-------
Table 3. Effect of Compound, Sample and Spike Level on Semivolatile CompoundDetectability
Compound
Number
5.
12.
13.
15.
16.
22.
25.
28.
33.
36.
43.
50.
51.
56.
57.
64.
65.
66.
69.
74.
76.
77.
80.
84.
85.
98.
100.
117.
118.
120.
121.
123.
125.
126.
132.
137.
Percent of Data Reported
by Given Laboratory***
Compound
4-Chhrotoluene
Bis(2-chloroethyl)ether
2-Chlorophenol
2,4. 6- Trimethylpyridine
1 , 4 -Dichlorobenzene
Acetophenone
Hexachloroethane
4-t-Butylpyridine
2, 4 -Dimelh yl phenol
Propiophenone
4-Chloroaniline
Quinoline
Bisf2-chloroethoxyjethane
4 • Chloro -3-methylaniline
4-Chlorobenzoic acid
1 -Chloronaphthalene
4-Methylquinoline
2-Ethylnapthalene
4-Bromobemoic acid
1 ,3-Dinitrobenzene
2, 6-Dinitrotoluene
3-Nitroaniline
2, 4 -Dinitrophenol
4-Nitrophenol
Pentachlorobenzene
2-Chloro-4-nitroanit/ne
Hexachlorobenzene
Anthraquinone
Fluoranthene
2-Methylanthraquinone
Pyrene
4,4' -ODD
4,4' -DDT
Triphen yl ph osphate
Tri-(p-tolyl)phosphate
Dibenzocarbazole
A verage
2
96
WO
100
59
70
89
89
44
56
89
74
100
56
41
33
33
63
100
22
63
44
44
0
11
74
22
100
100
100
78
WO
78
85
89
63
56
67
3
89
67
67
78
89
89
85
56
4
78
11
78
WO
22
0
0
67
11
11
19
56
7
0
11
78
15
89
78
89
67
22
89
74
89
41
11
51
4
89
96
89
37
100
89
100
89
89
89
56
89
89
78
78
44
89
89
22
78
78
78
56
11
100
59
89
89
100
89
100
89
89
78
89
11
77
5
11
78
0
22
78
67
78
67
0
89
Q
89
56
0
44
44
67
89
0
78
52
0
44
11
78
11
78
81
93
78
100
81
89
59
70
0
52
6
33
22
44
11
93
44
0
85
89
89
11
44
78
44
22
59
78
78
96
0
0
0
0
0
100
0
44
33
100
89
100
89
0
33
85
52
48
Average Percent
LowQ
44
45
44
23
80
72
43
50
30
78
22
61
67
32
11
40
73
45
15
10
58
4
0
8
76
31
70
68
98
73
22
84
74
57
52
22
47
High"
93
91
84
69
90
89
89
80
59
89
43
93
89
41
52
30
73
93
54
23
28
41
33
11
93
8
95
89
89
85
100
89
66
89
81
32
70
Totaf
64
73
60
41
86
76
70
68
48
87
30
80
76
37
35
36
73
73
30
48
46
26
20
9
86
21
80
76
96
80
84
85
67
70
70
26
59
'The maximum number of analytical runs for which data could be reported for each sample was 27
13 replicates x 9 laboratories).
The percent of data r^nnPri=total number of analytical runs for which data were reported^ wo
27
^Percent of data reported for compounds spiked at the low level are underlined.
cAverage of the percents of data reported for samples in which the compound was spiked at the low
level.
d/4 verage of the percents of data reported for samples in which the compound was spiked at the
high level.
'Average of the percents of data reported for all samples.
-------
Table 4. Effect of Removing Outliers on Precision for the Determination ofSemivolatile Compounds in NBS Standard Reference Material No. 1645
Number of Data
Amount-Found, ug/g
Percent Relative
Standard Deviation
Compound
Number
41.
72.
78.
90.
107.
109.
114.
117.
118.
121.
127.
130.
134.
136.
138.
139.
140.
Compound
Naphthalene
Acenaphthylene
Acenaphthene
Fluorene
Phenanthrene
Anthracene
Di-n -butyl phthalate
Anthraquinone
Fluoranthene
Pyrene
Benzofajanthracene
Chrysene
Benzolkjfluoranthene
Benzo(a)pyrene
lndeno(1,2,3-cd)pyrene
Dibenzofa. h)anthracene
Benzolg, h. i)perylene
using
A
18
18
15
14
18
18
15
17
24
24
24
24
21
21
21
21
20
• (jiven uati
B
15
15
12
11
15
15
12
14
21
21
21
21
18
18
18
18
17
3 set
C
12
12
9
8
12
12
9
11
18
18
18
18
15
15
15
15
14
Using
A
4
45
1
14
28
10
22
15
53
93
40
70
40
14
14
10
18
' (jiven uat.
B
1
13
1
2
3
2
4
10
34
69
33
62
27
9
9
7
13
a net
C
1
17
1
1
3
2
5
9
32
61
30
60
26
8
8
5
11
using 0
A
263
278
28
305
338
287
218
102
154
107
79
44
127
95
127
87
93
riven uati
B
20
111
27
42
26
87
48
30
23
23
38
18
28
33
48
73
48
) ier
C
18
90
24
23
13
74
30
15
18
15
32
17
28
18
36
48
29
"Data set A includes all reported data. The maximum number of data possible is 24 (3 replicates x 8 laboratories). One of the 9 laboratories did not
analyze this sample.
Data set B includes all reported data from 7 laboratories. One laboratory has been excluded.
Data set C includes all reported data from 6 laboratories. Two laboratories have been excluded.
The Project Report was prepared by Battelle-Columbus Laboratories, Columbus,
OH 43201; the Project Summary was prepared by Donald F. Gurka (also the
EPA Project Officer, see below) with the Environmental Monitoring Systems
Laboratory, Las Vegas, NV 89114.
The complete report, entitled "Interlaboratory Comparision Study: Methods for
Volatile and Semivolatile Compounds," (Order No. PB 84-178 482; Cost:
$29.50, subject to change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA2216J
Telephone: 703-487-4650
Environmental Monitoring Systems Laboratory
U.S. Environmental Protection Agency
P.O. Box 15027
Las Vegas, NV89114
------- |