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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