United States
Environmental Protection
Agency
Environmental Monitoring
Systems Laboratory
Cincinnati OH 45268
Research and Development
EPA/600/S4-8S/034 Feb. 1989
AEPA Project Summary
USEPA Method Study #39,
Method 504, 1,2-
Dibromoethane (EDB) and 1,2-
Dibromo-3-Chloropropane
(DBCP) in Water by
Microextraction and Gas
Chromatography
Kenneth W. Edgell
An interlaboratory collaborative
study was conducted to determine
the precision and bias (recovery) of
Method 504 for the analysis of two
semivolatile organic compounds in
groundwater. Method 504 is entitled
"1,2-Dibromoethane (EDB) and 1,2-
Dibromo-3-Chloropropane (DBCP)
in Water by Microextraction and Gas
Chromatography" and includes
instructions for quality control,
sample preparation and analysis of
samples by gas Chromatography
The study design was based upon
Youden's non-replicate plan for
collaborative tests of analytical
methods. Each water type was spiked
with three Youden sample pairs of
the two semivolatile compounds and
analyzed using method 504. The test
waters included reagent water as a
"control" and one ground water. The
resulting data were analyzed using
the USEPA computer program
entitled "Interlaboratory Method
Validation Study (IMVS)." The data
analyses produced measures of
precision and recovery for each
compound in each water type and
compared the performance of the
method between water types.
The study was conducted under
the auspices of the U.S. Environ-
mental Protection Agency, Cincin-
nati, Ohio, under EPA Contract No.
68-03-3254. This report covers a
period from June 1987 to December
1987. Analytical work was completed
as of October 1987.
This Project Summary was devel-
oped by EPA's Environmental Moni-
toring Systems Laboratory, Cincinnati,
OH, to announce key findings of the
research project that is fully docu-
mented in a separate report of the
same title (see Project Report
ordering information at back).
Introduction
The Office of Water (OW) of the U.S.
Environmental Protection Agency
(USEPA), gathers water quality data to
provide information on water resources
and drinking waters to monitor safe
drinking water quality, establish maxi-
mum contaminant limits, and assure
compliance or further regulations under
the Safe Drinking Water Act (1986) and
its amendments. The success of these
activities depends upon the reliability of
the data provided by the laboratories,
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particularly when legal actions are
contemplated .
EMSL-Cincinnati develops/selects
analytical methods and provides quality
assurance (QA) support to the Office of
Drinking Water (ODW) as required by
regulations. The QA program is designed
to maximize the reliability and legal
defensibility of water quality information
collected by the Agency, the primary
regulating authorities in the states, and
by the laboratories performing analyses
for public water supplies. The respon-
sibility for providing QA support is
assigned to the QA Branch of EMSL-
Cincinnati. One QA Branch activity is to
conduct interlaboratory method validation
studies on ODW's analytical methods to
obtain precision and bias statements for
the analytical methods specified for
regulated analytes.
The full report describes an inter-
laboratory method validation study on
Method 504 entitled "1,2-Dibro-
moethane (EDB) and 1,2-Dibromo-3-
Chloropropane (DBCP) in Water by
Microextraction and Gas Chroma-
tography." Ten commercial laboratories,
with demonstrated experience in the
analyses of drinking water, were
selected, based on technical criteria, to
participate in this study. The Bionetics
Corporation, as primary contractor to the
Quality Assurance Branch of EMSL-
Cincinnati, was responsible for the
collection and characterization of ground
water used as a test water in the study
and the subsequent spiking levels of the
analytes. Additional activities included
analyses of the samples to confirm the
true values, preparation of user
instructions and report forms, distribution
of the samples, screening of returned
data for gross errors, and drafting of the
final report. Statistical evaluation of the
raw data was performed using a series of
computer programs entitled "Inter-
laboratory Method Validation Studies"
(IMVS).
Procedure
Study Design
The study design was based on
Youden's original non-replicate design
for collaborative evaluation of precision
and recovery for analytical methods. Two
similar yet different samples were
prepared at each of three levels over the
selected range of concentrations such
that the concentration of the pairs varied
between 5-20% of the mean of the
pairs. Analysts were directed to do a
single analysis and report one value for
each sample. Analyses in reagent water
evaluated the proficiency of the method
on a sample free of interferences;
analyses in the other water were
intended to reveal the effects of matrix
interferences in the method.
Spiking solutions, standard solutions
and quality control samples were heat-
sealed in ampuls From each ampul,
containing 1.5 mL of solution, 35 &iL was
used to spike 35 mL of matrix water.
Ampul solutions were analyzed for true
values against standards freshly
prepared from neat materials prior to
distribution. At the completion cf the
study the ampuls were again analyzed
against freshly prepared standards to
verify the stability of the study samples
The ground water used for this study
was acquired from a well at a Superfund
hazardous waste site. The well was
purged prior to sample collection The
water samples were preserved by
adjusting the pH to 2.0 with 1:1 HCI then
mixed thoroughly to ensure homoge-
neity, dispensed into glass bottles with
Teflon lined lids and sealed in plastic
bags for shipment to the participating
laboratories.
Each of the ten participating labora-
tories received twelve ampuls (six
concentrations for each of two waters)
and instructions for spiking into the
waters. Each laboratory also received
four quality control sample ampuls and
instructions plus the "in control" limits.
Copies of the method, report forms, a
questionnaire and approximately 1 liter of
groundwater were provided to the
laboratories.
Each participating laboratory was
required to prepare full volume test
samples using the six Youden spiking
solutions spiked into their own reagent
water and the ground water provided. For
each water type a matrix blank and a
quality control sample were also ana-
lyzed. The laboratories were instructed to
analyze the samples using the exact
written method, and to complete the
analyses and report forms within a 60-
day period from receipt of samples.
A questionnaire was sent to the
participating laboratories requesting
information on instrument operating
conditions, type of instrumentation used,
problems encountered with the method,
and other variables associated with the
conduct of the method.
Selection of Participating
Laboratories
The Quality Assurance Branch was
responsible for the selection of the
participating laboratories. As per the
standard competitive bid process, an
abstract of the scope of work was
announced in the Commerce Business
Daily. Over 100 laboratories were
forwarded the request for proposal (RFP).
The evaluation criteria for the technica
proposal were:
• Suitability of the Project Managemem
Plan - This includes the experience 0'
the project manager in managing
contracts of a similar nature as this
contract, the suitability of the organ'
izational plan in that all roles, respon-
sibilities and authorities shall be clearlv
identified, and demonstrate the ability
of the offerer to provide the requirec
number of analyses within the period 0'
performance given in the contract.
• Personnel Qualifications - The offero
must demonstrate the experience of al
analysts involved in the method study.
• Suitability of Facilities and Instrumen
tation - The offeror must describe the
facilities and instrumentation which wil
be made available for this contract.
• Suitability of Quality Assurance Plan -
The offeror must describe what effort;
are to be made to ensure the quality
quantity and timeliness of the data.
All responses were evaluated an<
ranked. Technically acceptable labor
atories were sent performance evaluatioi
(PE) samples for analysis. Each offero
was required to bid separately on each c
eight different method validation studies
The offerers were instructed to analyzi
the samples utilizing the written method
and the same personnel and instrumen
tation as listed in their proposal for thi
formal study. The PE sample contamei
five purgeable volatile organics, fou
pesticides and three aldicarbs a
unknowns. The offerer's data wen
evaluated against statistics generated b
EMSL-QAB from past performanc
evaluation and method evaluatio
studies. Ten laboratories from the list c
technically acceptable laboratories wer
chosen based on the competitive rang
of cost.
Results and Discussion
The objective of this study was t
characterize the performance of Metho
504 in terms of recovery, overa
precision, single-analyst precision an
the effect of water types on bot
recovery and precision. Through th
Interlaboratory Method Validation Stud
(IMVS) computer programs, statistic;
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Table 1. IMVS Study 504, Regression Equations for Recovery and Precision
Water Type
1,2-Dibromoethane
1,2-Dibromo-3-
Chloropropane
Applicable Cone. Range
Reagent Water
Single-Analyst Precision
Overall Precision
Recovery
Ground Water
Single-Analyst Precision
Overall Precision
Recovery
(0.05 - 6.68) ngIL
SR = 0.41X + 0.004
S = 0.075 X + 0.008
X = 1.072C - 0.006
SR = 0.046X + 0.002
S = 0.102X + 0.006
X = 1.077C - 0.001
(0.05 - 6 40) pg/L
SR = 0.065X * 0.000
S = 0.143X -0.000
X = 0.987X-0.000
SR = 0.076X - 0.000
S = 0.160X + 0.006
X = 0.972C + 0.007
X = Mean recovery
C = True value for the concentration
analyses of 240 analytical values pro-
vided estimates of recovery and
precision expressed in regression equa-
tions presented in Table 1.
A detailed investigation of the number
of outliers is a good measurement of the
ruggedness of the method. In this study,
15% of the submitted data points were
rejected as outliers. The laboratory
ranking test, associated with systematic
errors, represented 67% of the total
rejected data while the individual outlier
,est accounted for the remaining 33%.
One laboratory accounted for 41 % of the
total outliers while 7 laboratories had no
)uthers for 1,2-dibromoethane and 8
laboratories had no outliers for 1,2-
dibromo-3-chloropropane. The ground
water produced no apparent matrix effect
on the number of outliers (7.1% outliers
in reagent water and 7.9% outliers in
ground water). The relatively low
percentage of outlier data indicated that
the method is rugged.
The recovery of the method was
obtained by comparing the mean values
from the study to the true value
concentrations. Recoveries of 107% and
108% for reagent water and ground
water were found for 1,2-dibromo-
ethane. For 1,2-dibromo-3-chloro-
propane recoveries of 99% and 97%
were found for reagent water and ground
water, respectively.
The overall standard deviation
expressed as the percent relative
standard deviation (%RSD) was 8% and
10% for 1,2-dibromoethane in reagent
water and ground water respectively, the
%RSD was 14% and 16% for 1,2-
dibromo-3-chloropropane in reagent
water and ground water, respectively.
The single-analyst standard deviation
expressed as the percent relative
standard deviation (%RSD-SA) was 4%
and 5% for 1,2-dibromoethane m
reagent water and ground water and 7%
and 8% for 1,2-dibromo-3-chloro-
propane in reagent water and ground
water, respectively.
The statistical comparisons of the data
across water types indicated no matrix
effects in the recovery or precision
regression equations.
Conclusions and
Recommendations
Method 504 is recommended for the
analyses of 1,2-dibromoethane and
1,2-dibromo-3-chloropropane in
water. The recovery, overall precision
and single-analyst precision were
acceptable. There was no significant
difference in performance between the
waters tested in this study.
Impurities contained in the extracting
solvent can account for many analytical
problems noted in this study. It is
recommended that only the highest
grade extraction solvent be obtained and
tested prior to use for analyses.
Instances of sample contamination
have been attributed to diffusion of
volatile organics through the septum seal
of unlined caps into the sample bottle
during shipment and storage. It is
recommended that Teflon-lined caps
with septum seals be used.
The primary column (Durawax - DX3,
0.25 urn film, 30 m x 0.32 mm) is
recommended for normal analyses,
because 1,2-dibromoethane, at low
concentrations, can be masked on the
confirmation column by high levels of
dibromochloromethane, a common
chlorinated drinking water contaminant.
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Kenneth W. Edgell is with The Bionetics Corporation, Cincinnati, OH 45246.
Raymond J. Wesselman, is the EPA Project Officer (see below).
The complete report, entitled "USEPA Method Study #39, Method 504, 1,2-
Dibromoethane (EDB) and 1,2-Dibromo-3-Chloropropane (DBCP) in Water
by Microextraction and Gas Chromatography," (Order No. PB 89-119 580/AS;
Cost: $15.95, subject to change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Environmental Monitoring Systems Laboratory
U.S. Environmental Protection Agency
Cincinnati, OH 45268
United States
Environmental Protection
Agency
BULK RATE
POSTAGE & FEES PAID
EPA
PERMIT No G-35
Official Business
Penalty for Private Use $300
EPA/600/S4-88/034
0000329 PS
U S ENV1R PROTECTION ftSENCT
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