United States
Environmental Protection
Agency
Environmental Monitoring
Systems Laboratory
Las Vegas, NV 89114
Research and Development
EPA/600/S4-85/060 Jan. 1986
v°/EPA Project Summary
Single-Laboratory Validation
of EPA Method 8150 for the
Analysis of Chlorinated
Herbicides in Hazardous
Waste
F. L Shore, E. N. Amick, S. T. Pan, and D. F. Gurka
A single-laboratory validated analyti-
cal protocol is described, which is appli-
cable to the determination of the herbi-
cides Dicamba, Silvex. 2,4-D, 2,4-DB,
2,4,5-T, Dinoseb, MCPP, and MCPA in
hazardous waste extracts. The method
consists of herbicide hydrolysis fol-
lowed by diazomethane esterffication
and subsequent determination of the
herbicide methyl esters by capillary
column gas chromatography with elec-
tron capture detection (GC/EC). An elec-
tron impact gas chromatography/mass
spectrometric (GC/MS) confirmation of
the GC/EC results is included.
The protocol validation procedure
consisted of (1) ruggedness testing,
(2) simplex optimization of key experi-
mental variables, and (3) the determi-
nation of extraction recoveries, detec-
tion limits, and the GC/EC linear
dynamic range for each herbicide
methyl ester. This protocol, which em-
ploys a single fused silica capillary
column separation for all the target
methyl esters, is a significant improve-
ment over all earlier gas chromato-
graphic (GO procedures, each of which
utilizes three different packed GC
columns. The method, however, was
inapplicable to Dalapon, which elimi-
nates hydrogen chloride during the
sample workup.
This Project Summary was devel-
oped by EPA's Environmental Monitor-
ing Systems Laboratory, Las Vegas,
NV, 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
The United States Environmental Pro-
tection Agency (EPA) is currently in-
volved in a program to determine the
accuracy and precision of key EPA ana-
lytical protocols. As part of this pro-
gram, the Office of Solid Waste (OSW)
is validating the protocols in its Manual
SW-846 Test Methods for Evaluating
Solid Waste. Included in Manual SW-
846 is Method 8150 for the determina-
tion of chlorinated herbicides, which is
based on earlier American Society for
Testing Materials (ASTM) and EPA pro-
cedures for determination of herbicides
in water. Method 8150, therefore, re-
quired validation for its applicability to
solid wastes.
Guidelines to aid in validating analyti-
cal procedures have been published by
ASTM and by the Association of Official
Analytical Chemists (AOAC). In addi-
tion, a step-by-step protocol for the val-
idation process has recently been pub-
lished (JAOAC, 66, 455, 1983).
The following work plan was utilized
for this method validation:
1. Evaluate the original analytical
protocol for Method 8150 as pub-
lished in Manual SW-846.
2. Locate key method variables by
ruggedness testing using
Youden's approach.
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3. Optimize key method variables
using the simplex optimization
technique.
4. Using the EPA format, prepare a
detailed analytical protocol for the
optimized method.
5. Determine the linear dynamic
quantification range for each
target methyl ester.
6. Determine the percent extraction
recovery for each target methyl
ester.
7. Prepare a GC/MS confirmation
technique for the optimized GC/EC
method.
8. Test the analytical protocol on
spiked extracts of hazardous waste
samples.
9. If sample results indicate proce-
dural problems, revise the analyti-
cal protocol, as necessary.
Conclusions and
Recommendations
A single-laboratory validated protocol
for determination of herbicides in haz-
ardous waste has been prepared. This
protocol is applicable to the determina-
tion of 9 of the 10 Method 8150 target
methyl herbicides. The exceptional
ester is Dalapon, which decomposes
during the sample workup. Final
ruggedness testing on the optimized
protocol for the 9 methyl esters yielded
a mean recovery of 89.3 percent with a
mean standard deviation of 4.3 percent
for 20 determinations. The GC/EC linear
dynamic range exceeded two orders of
magnitude for MCPP and MCPA and
three orders of magnitude for the
7 target esters. Detection limits were in
the ppm range for MCPP and MCPA and
in the low ppb range for the other herbi-
cides. These detection limits and linear
dynamic ranges reflect the wide span of
the target compound GC/EC response
factors. Although these detection limits
are adequate for hazardous wastes,
which typically contain ppm and higher
contaminant levels, we recommend
that appentafluorobenzyl GC/EC proce-
dure be evaluated for its applicability to
low-level environmental samples.
Results and Discussion
The original Method 8150 protocol
was modified to use a single, 20-minute,
fused silica capillary column GC run for
all target herbicide esters. This modifi-
cation yields substantial savings in GC/
EC data acquisition time over the three
packed GC columns specified in Method
8150. Methylene chloride was substi-
tuted for ether as the extraction solvent
to eliminate flammability and peroxide
problems. A sonication extraction pro-
cedure that has previously been suc-
cessful for solid waste extraction re-
placed the Method 8150 hand extraction
technique.
Ruggedness testing was employed to
locate the key protocol experimental
variables. Youden's experimental de-
sign was used to test seven experimen-
tal variables, at two levels each, in three
basic experiments. These experimental
designs are listed in Table 1. The three
key extraction variables were the vol-
ume and pH of the buffer and the soni-
cation power setting. The ester hydroly-
sis was sensitive only to the volume of
added methanol. Ruggedness testing
indicated that the optimized method
would have a percent relative standard
deviation (% RSD) of 11 or less.
Although ruggedness testing identi-
fies sensitive method variables, it does
not adjust these variables to their opti-
mum value. The simplex optimization
technique was selected to locate the
best value for each of the experimental
variables previously identified by
ruggedness testing. The simplex tech-
nique is rapid and the experimental data
generated can easily be computed by
hand calculator. The simplex derived
herbicide ester recoveries are listed in
Table 2. The simplex results led to the
preparation of a new analytical proto-
col.
Table 1. Ruggedness Testing of Free Acid Herbicide Extraction and Analysis
Experimental Variables
The GC/EC linear dynamic quantifica-
tion range and detection limit were de-
termined. These values are listed in
Table 2. The detection limits are higher,
and the quantification range is narrower
for MCPA and MCPP. Both of these con-
ditions result from a GC/EC detector re-
sponse which is weaker than that ob-
tained for the other herbicide esters.
This weaker response leads to GC
column overloading at the high end of
the linear dynamic range.
The effect of analyte level on extrac-
tion recovery was tested by spiking a
herbicide still bottom sample and a
kaolin clay, at various levels, with the
herbicide methyl esters. Workup and
subsequent analysis using the opti-
mized protocol clearly indicated in-
creased recoveries at higher analyte
levels.
A GC/MS method was developed to
confirm GC/EC tentative identifications.
The minimum quantity of herbicide
ester required to yield a Finnigan (NCOS
GC/MS computer search value of 800
(as recommended by the manufac-
turer's manual) under full scan condi-
tions was determined. These values
ranged from 0.3 to 4.5 nanograms.
Condition
No.
1.
2.
3.
4.
5.
6.
7.
Experiment
No. 1
pH of phosphate
buffer added to
clay
Acetone: hexane
ratio in sonication
Analyte concentration
Size of breaker used
for sonication
Base extraction or
acid wash of clay
extract
Clay extraction filter
Methylation solution
Experiment
No. 2
Volume of buffer or
water added to clay
pH of buffer or water
added to clay
Sonicator output
setting
Sonication temperature
Solvent volume in
sonication
Base extraction or acid
wash of clay extract
Amount of CH2N2
(molar excess)
Experiment
No. 3
pH of phosphate
buffer added
to clay
Volume of
buffer added
to clay
Extraction
solvent
Sonicator output
setting
Base extraction
or acid wash
of clay extract
Methylation
solution
Destruction of
excess CH2N2
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Table 2. Linear Dynamic Range, Detection Limit, and Percent Recoveries for Herbicide Methyl Esters
Linear Detection
Range Limit
Common Name Systematic Name (ng/mL) (ng/mL)*
2,4-D
2,4-DB
Dalapon
Dicamba
Dichlorprop
Dinoseb
MCPA
MCPP,
(Mecoprop)
Silvex
2,4,5-T
2,4-dichlorophenoxy acetic
acid
4-(2,4-dichlorophenoxy)
butyric acid
2,2-dichloropropanoic acid
3,6-dichloro-2-methoxy
benzole acid
2-<2,4-dichlorophenoxy)
propionic acid
2-sec-butyl-4, 6-dinitro
phenol
2-methyl-4-chlorophenoxy
acetic acid
2-(4-chloro-2-methyl-
phenoxy) propionic acid
2-<2,4,5-trichlorophenoxy)-
propionic acid
(2,4,5-trichlorophenoxy)
acetic acid
6.1
20.2
7.4
2.6
7.5
4.1
3.1
3.1
2.1
2.1
- 12200
-40300
-736
-520
- 15000
-8100
-306
-309
-4140
-4110
1.7
20.2
1.34
0.6
1.9
1.4
218.
333.
0.53
0.78
% Recovery
91.2
107.0
-
85.4
95.2
89.6
96.1
101.0
85.7
80.9
"Quantity of herbicide methyl ester yielding a GC/EC detector response with S/N a 3.
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F. L Shore, E. N. Amick. and S. T. Pan are with Lockheed Engineering and
Management Services, Co., Inc., Las Vegas, NV 89114; the EPA author D. F.
Gurka (also the EPA Project Officer, see below) is with the Environmental
Monitoring Systems Laboratory, Las Vegas, NV 89114.
The complete report, entitled "Single-Laboratory Validation of EPA Method 8150
for the Analysis of Chlorinated Herbicides in Hazardous Waste," (Order No. PB
86-108 404/AS; Cost: $16.95, 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
P.O. Box 15027
Las Vegas, NV 89114
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
Official Business
Penalty for Private Use $300
EPA/600/S4-85/060
000053? PS
U S FNVIR PROTECTION AGENCY
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CHICAGO IL 60604
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