United States
Environmental Protection
Agency
Environmental Monitoring and
Support Laboratory
Cincinnati OH 45268
Research and Development
EPA/600/S4-85/080 Jan. 1986
&ER& Project Summary
EPA Method Study 32:
Method 450.1Total Organic
Halides (TOX)
Carol H. Tate, Bruce M. Chow, Robert R. Clark, Nancy E. Grams, and Lewis
K. Hashimoto
oil
U
The full report describes the interlab-
oratory method study that was per-
formed to evaluate Interim Method
450.1 for total organic halides (TOX). In
the method, a measured volume of
water is passed through two columns
in series, each containing 50 mg of acti-
vated charcoal. Organic halides (OX)
present in the water are adsorbed onto
the charcoal which is washed to elimi-
nate trapped inorganic halides. The
contents of the columns are then py-
rolyzed, converting the halides to titrat-
able species that are measured micro-
coulometrically. In this study, three
water matrices, reagent water, ground-
water and surface water, were spiked
at six concentrations with a solution
containing a combination of four chlori-
nated compounds. These were lindane,
bromoform, pentachlorophenol, and te-
trachloroethene. A chlorinated drinking
water diluted to four concentrations
with reagent water was also analyzed.
Ten laboratories participated in the
study. Data obtained were analyzed
using a computerized statistical pro-
gram package known as Interlabora-
tory Method Validation Study (IMVS),
which is designed to implement the
recommendations of ASTM Standard
D-2777. The IMVS package includes
outlier tests; estimation of mean recov-
ery as a measure of bias; estimation of
single-analyst and overall precision;
and tests for effects of water type on
these statistical estimates.
This report was submitted in fulfill-
ment of Contract No. 68-03-3163 by
James M. Montgomery, Consulting En-
gineers, Inc. It covers work performed
from September 1982 to June 1985.
This Project Summary was devel-
oped by EPA's Environmental Monitor-
ing and Support Laboratory, Cincinnati,
OH, to announce key findings of the re-
search project that is fully documented
in a separate report of the same title
(see Project Report ordering informa-
tion at back).
Introduction
Several of the laboratories of the
USEPA gather water quality data to pro-
vide information on water resources, to
assist research, and to evaluate pollu-
tion abatement activities. The success
of these pollution control activities de-
pends on the reliability of data provided
by the laboratories.
The Environmental Monitoring and
Support Laboratory-Cincinnati (EMSL-
Cincinnati) of USEPA develops or se-
lects analytical methods and conducts
quality assurance programs for the
water laboratories. EMSL-Cincinnati's
quality assurance program is designed
to maximize the reliability and legal de-
fensibility of all water quality informa-
tion collected by USEPA laboratories.
The responsibility for these activities is
assigned to the Quality Assurance
Branch (QAB), which conducts interlab-
oratory tests of the methods.
The method evaluated in this report
was prepared by the EMSL-Cincinnati
and Water Engineering Research Labo-
ratory (WERL) staff at the request of the
Office of Drinking Water, with coopera-
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tion from its Technical Support Divi-
sion.
Results and Discussion
With the use of the IMVS system, esti-
mates of precision and bias were made
and expressed as the regression equa-
tions (see Table 1). Of the 220 analytical
values, 27 or 12.3 percent were rejected
as outliers. The bias of the method was
estimated by comparing mean recover-
ies to true TOX values at six concentra-
tion levels between 38.7 and 441.1 \j.g/L.
The average recovery calculated from
the regression equations was 86.5 per-
cent, with the actual recoveries ranging
from 83.5 percent to 117.2 percent. The
highest recoveries occurred at the low-
est concentration levels.
The overall standard deviation, S,
was not_significantly dependent on re-
covery X, as indicated by slopes of re-
gression equations for X ranging from
-0.0128 to 0.0374. The intercepts
ranged from 6.4 to 14.1 and closely ap-
proximated the actual S values ob-
tained for the low, medium and high
concentration ranges: 2.9 to 14.4 jxg/L,
5.7 to 14.1 |j.g/L and 10.4 to 15.4 (ig/L,
respectively. Percent relative standard
deviations for low, medium and high
Youden pair samples were 7.2 to
31.8 percent, 3.2 to 6.6 percent, and 3.0
to 4.4 percent, respectively.
The single-analyst precision, Sr,
showed little dependence on recovery
X. The slopes of the regressions for Sr
ranged from -0.0092 to 0.0033, with in-
tercepts ranging from 5.48 to 12.7.
Single-analyst precision values actually .
obtained for low, middle and high con-
centrations ranged from 5.7 to 12.3, 4.5
to 9.3, and 9.4 to 12.0, respectively.
Single-analyst relative standard devia-
tions for low, middle and upper concen-
trations were 11.8 to 23.7 percent, 2.2 to
3.9 percent, and 2.5 to 3.4 percent,
respectively.
No regression equation for TOX re-
covery from chlorinated drinking water
was calculated due to the absence of a
true concentration value for that sample
type. Regressions calculated for overall
S and Sr against mean analyzed value,
X, yielded an equation for S with a
strongly negative intercept. The equa-
tion generated did not accurately pre-
dict the S values obtained from the
study data and was considered invalid.
The most probable cause for this was
considered to be the use of four rather
than six concentration levels for calcula-
tion of the regression. Individual S val-
ues for the four water samples ranged
Table 1. Regression Equations for Precision and Bias
Water Type X~ S
Reagent
Surface
Ground
Chlorinated Drink-
ing Water
X
X
X
= 0.807C -
= 0.894C H
= 0.896C H
h 74.7
H7.74
1-6.38
S
S
S
S
= -0.0128 X
= 0.0374 X +
= 0.0280 X +
= 0.0946 X -
+ 14.2
2.68
3.40
9.22 ;
Sr= -0.0092X+ 72.7
Sr = -0.0109 X +6.14
Sr = 0.0033 X +5.48
Sr = 0.1037 X -0.1014
X = Mean recovery (bias) as \>.g/L.
S = Overall precision as \i.g/L.
Sr = Single-analyst precision as \i.g/L.
C = True value as \ig/L.
from 3.1 to 7.9 for TOX concentrations
between 63.8 p-g/L and 83.6 n-g/L For
TOX concentrations in the range of
137.8 to 178.5 n,g/L, S values ranged
from 12.7 to 29.6 \t,g/L. Single-analyst
precision ranged from 4.5 at the low
concentration range to 22.8 p,g/L for the
higher concentration range.
Statistical comparisons of the effect
of water type were performed. No sig-
nificant effect of water type on bias or
precision of Method 450.1 was
observed.
Conclusions and Recommenda-
tions
Method 450.1 is recommended for
the analysis of total organic halide
(TOX) in drinking, ground and surface
waters. The method bias and precision
are acceptable and there are no signifi-
cant matrix effects with the waters listed
above. The "Interim" designation
should be removed from the current
title of the method.
To ensure more consistent perform-
ance of the method, several ambigu-
ous points that became apparent dur-
ing Phase I of the study should be
clarified.
Additional research should be con-
ducted on performances of the
method when analyzing chlorinated
drinking water supplies.
In order to avoid TOX carryover from
one sample to the next, the sample
reservoir should be rinsed with two
100-mL volumes of distilled water be-
fore adding another sample.
Users of the method must take pre-
cautions to avoid contamination of
the samples and the analytical sys-
tem, especially when analyzing sam-
ples expected to have low TOX con-
centrations. The potential for
contamination from contact with the
fingers can be greatly reduced by fol-
lowing the instructions found in Sec-
tion 5.2.4 of the method.
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Carol H. Tate. Bruce M. Chow, Robert R. Clark. Nancy E. Grams, and Lewis K.
Hashimoto are with James M Montgomery, Consulting Engineers, Inc.,
Pasadena, CA 91101-7009}.
Terence M. Grady is the EPA Project Officer (see below).
The complete report, entitled "EPA Method Study 32: Method 450.1 Total
Organic Ha/ides (TOX)." (Order No. PB 86-136 538/AS; Cost: $11.95, subjectto
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
United States Center for Environmental Research
Environmental Protection Information
Agency Cincinnati OH 45268
Official Business
Penalty for Private Use $300
EPA/600/S4-85/080
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