United States
Environmental Protection
Agency
Environmental Monitoring and
Support Laboratory
Cincinnati OH 45268
Research and Development
EPA-600/S4-84-037 June 1984
4?EPA Project Summary
EPA Method Study 26,
Method 613:
2,3,7,8-Tetrachlorodibenzo-p-
Dioxin
Fred D. Hileman, David E. Kirk, Thomas Mazer, Arthur D. Snyder, Beverly J.
Warner, and Carl R. McMillin
The experimental design and results
of an interlaboratory study for an
analytical method to detect 2,3,7,8-
tetrachlorodibenzo-p-dioxin in water
are described herein. In USEPA's
Method 613, water containing an
internal standard (labeled 2,3,7,8-
TCDD) is extracted with methylene
chloride, concentrated, exchanged to
hexane, and then subjected to capillary
column gas chromatography/mass
spectrometric (GC/MS) analysis,
which allows for separation and
measurement of the 2,3,7,8-TCDD
isomer in the extract. The method study
consisted of the replicate analyses of a
performance evaluation sample used
primarily for determining laboratory
competence for 2,3,7,8-TCD D specific
analyses and subsequent analyses of six
sample concentrations and a blank in
six different waters (42 samples).
Statistical analyses and conclusions in
this report are based on analytical data
obtained by eleven collaborating
laboratories.
Participating laboratories were
selected based upon technical
evaluation of proposals and upon
technical evaluation of proposals and
upon the analytical results of prestudy
samples. Data obtained from the.
interlaboratory study were analyzed
employing USEPA series of computer
programs known as the Interlaboratory
Method Validation Study (IMVS)
system, which was designed to
implement the concepts recommended
in ASTM Standard D-2777.
The statistical analyses included tests
for the rejection of outliers, estimation
of mean recovery (accuracy), estima-
tion of single-analyst and overall
precisions, and tests for the effects of
water type on accuracy and precision.'
This Project Summary was deve/oped-
by EPA's Environmental .Monitoring-/
and Support Laboratory. Cincinnati,:
OH, to announce key findings of the-'';
research project that isfullydocumen&"<'
ed in a separate report of the same'title f
(see Project Report ordering in forma- ••
tion at back). ' ' . ' ' -•• '•-"'-
Introduction * ,
The analytical laboratories of the U.S.
Environmental Protection Agency
(USEPA) gather water quality data to
provide information on water resources,
to assist research activities, ancl to evalu-
ate pollution abatement activities. The
success of these pollution control
activities, particularly when legal action
is involved, depends upon the reliability of •
the data provided by the laboratories.
Under provisions of the Clean Water
Act, the USEPA is required to promulgate
guidelines establishing test procedures
for the analysis of pollutants. The Clean
Water Act Amendments of 1977,
emphasize the control of toxic pollutants
and declare the 65 "priority" pollutants
and classes of pollutants to be toxic under.
Section 307(a) of the Act, This report is
one of a series that investigates the
analytical behavior of selected priority
pollutants and suggests a suitable test
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procedure for their measurement. The
priority pollutantto be analyzed by Method
613 is 2,3,7,8-TCDD. The Environmental
Monitoring and Support Laboratory—
Cincinnati (EMSL) of the USEPAdevelops
analytical methods and conducts a quality
assurance (QA) program to maximize the
reliability and legal defensibility of all
water quality information collected by
USEPA laboratories.
The responsibility f or QA is assigned to
the Quality Assurance Branch which
conducts interlaboratory method
validation studies. This study reports the
results of the interlaboratory study on
Method 613 (Study 26).
Procedure
Phase I included preliminary method
study work conducted by Monsanto
Research Corporation to (1) evaluate the
original Method 613 as published in the
December 3, 1979 Federal Register; (2)
determine the method's minimum detec-
tion limit; and, (3) determine the storage
stability of 2,3,7,8-TCDD/acetone solu-
tions in ampuls over a 90-day period. Asa
result of the Phase I Study, Method 613
was revised to substantially alter the
sample processing steps. These revisions
are now included in the version of
Method 613 as presented in test method
manual, "Method for Organic Chemical
Analysis of Municipal and Industrial
Wastewater," EPA-600/4-82-057, July
1982.
Phase II involved the selection of
participating laboratories that could
demonstrate satisfactory analytical
results using their personnel and equip-
ment. This selection was based partially
on analysis of a performance evaluation
sample of mixed tetrachlorodibenzo-p-
dioxin isomers for 2,3,7,8-TCDD.
Phase III, the formal interlaboratory
study, required analyses of 2,3,7,8-TCDD
in six water types at each of six concen-
, trations (three Youden pairs) in addition
to the analysis of all water blanks with no
Spiked compound. Each participating
laboratory then forwarded a report to
Monsanto Research Corporation
containing all data obtained, and a
completed questionnaire covering
specifics on the analyses including the
source of distilled, tap and surface
waters, instrumentation used, GC
conditions, and specific problems
encountered in the analyses.
The final step in the study was a statis-
tical analysis of all data by Battelle Col-
umbus Laboratories, Columbus, Ohio,
under USEPA Contract No. 69-03-2624
employing USEPA's IMVS system of
computer programs.
Results and Discussion
The objective of this study was to char-
acterize the performance of Method 613
in terms of accuracy, overall precision,
single-analyst precision, and the effects
of water types on accuracy and precision.
Through statistical analyses of 396
analytical values, estimates of accuracy
and precision were made; these are
expressed as regression equations in
Table 1. The accuracy is obtained by
comparing the mean recovery to the true
values of the concentration. The average
percent recovery is 91% with a range
from 86% to 96%.
The overall relative standard deviation
(RSD) indicates the precision associated
with measurements generated by a group
of laboratories. The average percent rela-
tive standard deviation is 21% with a
range of 18% to 23%.
The relative single-analyst standard
deviation (RSD-SA) indicates the
precision associated within a single
laboratory relative to the mean recovery.
The average percent relative standard
deviation for a single analyst is 1 6% with
a range of 13% to 18%.
A statistical comparison of the effect of
the water types indicated no statistically
significant differences between water
types.
Correct activation of the alumina
column is critical. Overactivation causes
adsorption which results in incomplete or
no elution of TCDD from the column.
Some laboratories experienced poor
recovery and poor precision on the
labeled compounds. As a quality control
measure, a second independent internal
standard or surrogate should be used to-
detect possibje^errpr irj) knqwri^concen-
tration, evaporated 'concentration,"or
incomplete dissolution of standards.
Six of the eleven laboratories
experienced little or no difficulty with
Method 613. In these cases, over 98% of
the data points were retained (4 outliers
out of 216 analyses). All data from one
laboratory which used an incorrect inter-
nal standard were rejected. Of the remain-
Table 1. Regression Equations for Accuracy and Precision 2,3,7,8-TCDD
(Concentration Range 21-202 ppt)
Water Type
2,3,7,8-TCDD
Distilled water
Single-analyst precision
Overall precision
Accuracy
Tap water
Single-analyst precision
Overall precision
Accuracy
Surface water
Single-analyst precision
Overall precision
Accuracy
Wastewater 1
Single-analyst precision
Overall precision
Accuracy
Wastewater 2
Single-analyst precision
Overall precision
Accuracy
Wastewater 3
Single-analyst precision
Overall precision
Accuracy
SR = 0.13X + 1.29
S = 0.19X +0.28
X = 0.86C + 1.45
SR = 0.01X+ 7.78
S = 0.22X + 0.80
X =0.810 + 4.82
SR = 0.09X + 2.25
S=0.21X — 1.11
X = 0.80C + 3.93
SR = 0.25X — 4.41
S = 0.28X — 4.63
X = 0.940+ 1.03
SR = 0.06X + 2.71
S_ = 0.16X + 3.12
X = O.82C + 4.30
SR = 0.16X + 0.49
S_ = 0.20X + 0.01
X = 0.780+ 4.26
X = mean recovery
C = true concentration
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ing four laboratories, 66% of the data
were found to be outliers. In these cases,
three problems were identified:
(1) difficulty with alumina cleanup
{Laboratories 4 and 11).
(2) no recovery on 12C13 internal stan-
dard (Laboratory 6).
(3) lack of sensitivity at low levels of
TCDD (Laboratory 8).
Conclusions and
Recommendations
Method 613 is recommended for the
analyses of 2,3,7,8-TCDD in municipal
•and industrial wastewaters.
To increase sensitivity, place the end of
the column as close to the ion source as
possible. '_
the alumina column should be checked
for proper activity. Overactivated alumina
can cause adsorption of 2,3,7,8-TCDD
which is not eluted or incompletely el uted
by the solvent eluent.
Because some laboratories reported
poor precision and experienced
interferences with the labeled
compounds, the use of a second internal
standard or surrogate is recommended to
detect errors in known concentration,
evaporated concentrations or incomplete
dissolution of standards.
F. D. Hileman, D. E, Kirk, T. Mazer, A. D. Snyder, B. J. Warner, andC. R. McMillin
are with Monsanto Research Corporation, Dayton, OH 45407.
R. J. Wesselman is the EPA Project Officer (see below).
The complete report, entitled "EPA Method Study 26, Method 613, 2,3,7,8-
Tetrachlorodibenzo-p-Dioxin,"(OrderNo. PB84-188879;Cost:$11.50, 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 and Support Laboratory
U.S. Environmental Protection Agency
Cincinnati, OH 45268
•ft U.S. GOVERNMENT PRINTING OFFICE; 1984 — 759-015/7717
3:
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