United States
Environmental Protection
Agency
Environmental Monitoring
Systems Laboratory
Las Vegas. NV 89193-3478
Research and Development
EPA/600/S4-90/021 Sept. 1990
Project Summary
Application of Open-Tubular
Columns to SW-846 GC
Methods
V. Lopez-Avila, E. Baldin, J. Benedicto, J. Milanes, and W.F. Beckert
The document "Test Methods for
Evaluating Solid Waste," Office of
Solid Waste, Manual SW-846, provides
a compilation of methods for eval-
uating RCRA solid wastes for environ-
mental and human hazards. One of
the methods in this document,
Method 8000, provides guidance on
gas chromatographic analysis with
specific details on instrument cal-
ibration, maintenance, and quality
control. Since most of the GC
methods in the SW-846 manual
specify the use of packed columns,
and since for the past 10 years the
scientific community has had access
to the fused-silica capillary column
technology, we were asked by the
U.S. Environmental Protection Agency
to develop gas chromatographic pro-
cedures that employ fused-silica
open-tubular columns. When com-
pared to packed columns, the open-
tubular columns offer improved
resolution, and thus better selectivity,
increased sensitivity, and shorter
analysis times. Furthermore, when
injection is performed using an
injection tee and two dissimilar
columns connected to two identical
detectors, then sample throughput is
increased by a factor of two because
the primary and confirmatory
analyses are being conducted simul-
taneously We have used the dual-
column/dual-detector approach in
this study to establish gas chromato-
graphic conditions for six groups of
target analytes: Method 8040 phenols,
Methods 8080/8081 organochlorine
pesticides, Method 8090 nitroaro-
matic compounds, Method 8110
haloethers, Method 8120 chlorinated
hydrocarbons, and Methods
8140/8141 organophosphorus pesti-
cides. In each case, the list of target
analytes was expanded to cover more
target analytes than those currently
listed in the methods mentioned
above. The approach taken was as
follows: select columns for the dual-
column/dual-detector approach, es-
tablish conditions that give the best
chromatography for the target
analytes in terms of resolution and
peak shape, establish method repro-
ducibility and linearity, select at least
one internal standard and surrogate
compound per method, and finally
test the procedure with blind
performance evaluation samples of
known composition as well as with
extracts of real matrices.
This Project Summary was
developed by EPAs Environmental
Monitoring Systems Laboratory,
Vegas, NV, to announce key findings
of the research project that is fully
documented in a separate report of
the same title (see Project Report
ordering information at back).
Introduction
Regulation of hazardous wastes under
the Resource Conservation and Recovery
Act (RCRA) of 1976 and its elements
requires use of analytical methodologies
that provide reliable data. The document
"Test Methods for Evaluating Solid
Waste," Office of Solid Waste Manual
SW-846, revised recently (1), provides a
compilation of methods for evaluating
RCRA solid wastes for environmental and
human health hazards. One of the
methods in this document, Method 8000,
provides guidance on gas chromato-
-------
graphic analysis with specific details on
sample extraction, extract cleanup, and,
occasionally, derivatization of analytes
being given in the various methods
included in this manual. Since most of
the methods in the SW-846 manual
specify the use of packed columns, and
since for the past ten years the scientific
community had access to the fused-silica
capillary column technology, we were
asked to develop gas chromatographic
procedures that employ fused-silica
open-tubular columns. When compared
to packed columns, the open-tubular
columns offer improved resolution, and
thus better selectivity, increased sen-
sitivity, and faster analyses. Furthermore,
when analysis is performed using an
injection tee and two dissimilar columns
connected to two identical detectors, then
sample throughput is increased by a
factor of two because the primary and
confirmatory analyses are being con-
ducted simultaneously. We have used
the dual-column/dual-detector approach
in this study to select gas chromato-
graphic conditions for six groups of target
analytes: Method 8040 phenols, Methods
80808081 organochlorine pesticides,
Method 8090 nitroaromatic compounds,
Method 8110 haloethers, Method 8120
chlorinated hydrocarbons, and Methods
8140 8141 organophosphorus pesticides.
The results of the study presented in
this report indicate that the dual-column/
dual-detector approach using two 30-m x
0 53-mm ID fused-silica open-tubular col-
umns coated with dissimilar stationary
phases and connected to either an 8-in
injection tee or a press-fit Y-shaped
splitter is reliable for the gas chromato-
graphic determination of the target
compounds mentioned above. Also in-
cluded in this report as an appendix is a
literature review covering the state-of-the-
art technology on the 0.53-mm ID fused-
silica open-tubular columns and a proto-
col for the gas chromatographic
determinations using the dual-column/
dual-detector approach.
Experimental
Apparatus
a. Gas chromatographs - Varian 6000
with constant-current/pulsed-frequency
dual electron capture detector (ECD)
interfaced to a Varian Vista 402 data
system; Varian 6500 with constant-
current/pulsed-frequency dual ECD
interfaced to a Varian Vista 604 data
system; Varian 3700 with constant-
current/pulsed-frequency dual ECD
interfaced to two Spectra-Physics
SP4290 integrators.
b. Autosampler - Varian, Model 8000
c. GC Columns - DB-5 and DB-1701, 30-
m x 0.53-mm ID fused-silica open-
tubular columns for the analysis of
phenols, organochlorine pesticides,
nitroaromatics, haloethers, and chlorin-
ated hydrocarbons; DB-5 and DB-210,
30-m x 0.53-mm ID fused-silica open-
tubular columns for the analysis of
organophosphorus pesticides. The GC
operating conditions are given with the
individual methods.
d. Splitters - J&W Scientific press-fit Y-
shaped 3-way union glass splitter or
Supelco 8-in glass injection tee.
Materials
Standards - Analytical reference
standards of the test compounds were
obtained from the U.S. Environmental
Protection Agency, Pesticides and
Industrial Chemicals Repository, Aldrich
Chemical, and Ultra Scientific Incor-
porated. Purities were stated to be better
than 98 percent. Stock solutions of each
test compound were prepared at 1 mg/
ml_. Working calibration solutions were
prepared in hexane by serial dilutions of
a composite stock solution prepared from
the individual stock solutions.
Samples - EPA WP-281 Samples 2
and 4 were analyzed for the 34 phenols;
EPA WP-186 Sample 3, EPA WP-285
Samples 1 2, and 3, and EPA WP-286
Sample 1 were analyzed for the 22
chlorinated hydrocarbons.
Matrices - Matrices 1 and 2 were soil
samples taken from a farm in Northern
California that was known to have used
organochlorine pesticides, diazinon, eth-
ion, ziram carbaryl, benomyl, carbo-
phenothion, and malathion. Matrix 3 was
a wood sample that may have been
contaminated with pesticides. Matrix 4
was a soil sample identified as "S2A
Greenhouse South." Matrix 5 was a soil
sample identified as GJ 230, EPA CLP
Case 12449. Matrix 6 was a soil sample
from an unknown source. These samples
were extracted by sonication with
methylene chloride/ acetone (1:1) at least
10 months prior to this study, and the
extracts were cleaned up by gel
permeation chromatography. Following
cleanup, the extracts were frozen at
-20°C. Only the extracts spiked with the
organochlorine pesticides were subjected
to additional diol cartridge cleanup prior
to analysis by gas chromatography.
Derivatization
Derivatization of phenols -
Individual phenol stock solutions were
prepared at 1 mg/mL in hexane. A
composite solution at 20 ng/mL per
component was prepared by combining
the individual stock solutions and by
dilution with hexane. One hundred nL of
the composite solution was added to 8
ml_ acetone in a 10-mL graduated con-
centrator tube with screw caps. To this
solution, 100 pL of 5-percent pentafluoro-
benzyl bromide (PFBBr) reagent and 100
pL of 10-percent K2CO3 solution were
added. The contents were mixed by
shaking the capped tube gently. The
capped tube was heated in a water bath
at 60°C for one hour. The solution was
cooled to room temperature and concen-
trated to 0.5 ml_ using nitrogen
blowdown.
Results and Discussion
Phenols
The current EPA Method 8040 pro-
vides gas chromatographic procedures
for the determination of 11 phenolic
compounds. Analysis is performed either
by gas chromatography using a flame
ionization detector or by derivatization of
the phenolic compounds with PFBBr and
detection with an electron capture
detector. We have expanded the list of
the Method 8040 compounds to the 34
compounds presented in Table 1.
The 34 phenols listed in Table 1 were
derivatized with PFBBr according to a
method by Lee et al. (2). By examining
the data in Table 1, we concluded that
neither column could separate all 34
compounds. Five pairs were co-eluting
on the DB-5 column and three pairs were
co-eluting on the DB-1701 column. The
pairs that were co-eluting (complete over-
lap) on the two columns are identified as
follows:
DB-5: 2,6-dimethylphenol/
2,5-dimethylphenol
2,4-dimethylphenol/
2-chlorophenol
2,6-dichlorophenol/
4-chloro-2-methylphenol
2,4,5-trichlorophenol/
2,3,5-trichlorophenol
2,3,4,5-tetrachlorophenol
/2,5-dinitrophenol
DB-1701: 3-chlorophenol
/3,4-dimethylphenol
2,4-dichlorophenol
/3,5-dichlorophenol
2,4,5-trichlorophenol
/2,3,5-trichlorophenol
In addition, 3-methylphenol was only
partially resolved from 4-methylphenol on
the DB-5 and the DB-1701 columns, and
2-chlorophenol was only partially
resolved from 2,3-dimethylphenol on the
-------
Compound
No.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
/S-TC
/S-2c
St/c
Compound
Phenol
2-Methylphenol
3-Methylphenol
4-Methylphenol
2, 6-Dimethylphenol
2,5-Dimethylphenol
2,4-Dirnethylphenol
2,3-Dimethylphenol
2-Chlorophenol
3-Chlorophenol
3,4-Dimetbylphenol
4-Chlorophenol
2 -Chloro -5 -methyl phenol
2, 6-Dichlorophenol
4-Cbloro-2-methylphenol
4-Chloro-3-methylphenol
2, 5 -Dichloropbenol
3, 5 -Dichlorophenol
2, 4 -Diehlorophenol
2,4,6-Trichlorophenol
2, 3 -Dichlorophenol
3,4 -Dichlorophenol
2,3,6-Trichlorophenol
2-Nitrophenol
2,4,5-Trichlorophenol
2,3,5-Trichlorophenol
3-Nitrophenol
2,3,5,6-Tetrachlorophenol
2,3,4,6-Tetrachlorophenol
2,3,4-Trichiorophenol
4-Nitrophenol
2,3,4,5- Tetrachlorophenol
Pentachlorophenol
2,5-Dinitrophenol
2, 5 -Dibromotoluene
2,2',5,5'-Tetrabromobiphenyl
2,4-Dibromophenol
CAS No.
108-95-2
95-48-7
108-39-4
106-44-5
255117-01-5
66502-87-0
105-67-9
86260-39-1
95-97-8
108-43-0
b
106-48-9
80996-91-4
87-65-0
1570-64-5
59-50-7
583-78-8
591-35-5
120-83-2
88-06-2
576-24-9
95-77-2
933-75-5
88-75-5
95-95-4
933-78-8
554-84-7
935-95-5
58-90-2
15950-66-0
100-02-7
4901-51-3
87-86-5
25550-58-7
b
b
b
DB-5
RT(min)
4.69
5.68
6.05
6.21
7.08
7.08
7.34
7.96
7.34
7.86
8.46
8.19
9.12
9.73
9.73
10.18
10.71
11.02
11.02
12.85
12.01
12.51
13.93
12.51
15.02
15.02
13.69
17.71
17.96
16.81
15.69
20.51
22.96
20.51
3.16
25.16
16.02
DB-1701
RT(min)
6.36
7.44
7.99
8.13
8.83
9.02
9.27
10.11
10.24
10.78
10.78
11.31
12.25
12.52
12.89
13.31
14.37
14.75
14.75
15.76
16.22
16.67
17.36
19.19
19.35
19.35
20.06
21.18
21.49
21.76
22.93
25.52
26.81
30.15
3.18
28.68
20.56
a The GC operating conditions were as follows: 30-m x 0.53-mm ID DB-5 (0.83-iim film
thickness) and 30-m x 0.53-mm ID DB-1701 (1.0-nm film thickness) connected to an 8-ln
injection tee (Supelco Inc.). Temp program: 150°C (1-min hold) to 275°C (2-min hold) at
3°C/min; injector temp. 250°C; detector temp. 320°C; helium carrier gas 6 mL/min;
nitrogen makeup gas 20 mL/min.
b Not available.
c IS = internal standard; SU = surrogate compound.
DB-1701 column. Although the two col-
umns are quite different in polarity, the
elution order of the 34 compounds was
not drastically altered when we compared
the data from the two columns.
Twenty-four compounds were deter-
mined under the conditions established
for the PFB derivatives of the phenolic
compounds in order to select an internal
standard. Two internal standards, one
that elutes early (2,5-dibromotoluene) and
one that elutes late (2,2',5,5'-tetrabromo-
biphenyl) were recommended. Nine
phenolic compounds containing either
fluorine or bromine on the benzene ring,
a naphthol, and a phenylphenol were
derivatized with PFBBr and analyzed
under the conditions given in Table 1. All
but one compound (2,4-dibromophenol)
co-eluted with the target phenols; there-
fore, 2,4-dibromophenol was selected as
the surrogate compound.
To determine the reproducibility of the
injection technique (in terms of the
individual retention times and detector
responses) when using the dual-column/
dual-detector approach, we performed a
series of 10 consecutive injections on the
DB-5 and the DB-1701 column pair. The
retention time reproducibility (percent
RSD) was better than 0.33 percent for the
DB-5 column and 0.34 percent on the
DB-1701 column. The reproducibility of
the detector response for the DB-5
column was better than 1.8 percent
except for the 2,3-dimethylphenol/3-
chlorophenol and the 2,3,4,5-tetrachloro-
phenol/2,5-dinitrophenol pairs at 14.7 and
13.8 percent, respectively. The
-------
reproducibility of the detector response
for the DB-1701 column was better than
8.2 percent, with 21 values under 4
percent, and with the exception of three
compounds for which the RSD values
were between 11.8 and 12.2 percent.
The method linearity was established
from two sets of calibrations. The linear
ranges for both the DB-5 and DB-1701
columns were found to lie between 20 pg
and 160 pg, which was very narrow since
it covered only one order of magnitude
between the minimum quantifiable
amounts and the maximum quantities be-
fore detector overloading occurred. Most
correlation coefficients were greater than
0.95 but below 0.990 (for 24 of the 34
analytes) when the DB-1701 column was
used. The daily variation of detector
response factors (percent difference)
were determined one day and two days
after the multilevel calibration. Significant
increases in the percent differences were
observed for the DB-1701 column two
days after the calibration was performed.
These results indicate that the gas
chromatographic system requires daily
calibration
Organochlorlne Pesticides
The current EPA Methods 8080/8081
provide gas chromatographic procedures
for the determination of 18 organo-
chlorine pesticides, toxaphene, and
Aroclors The analysis is performed by
gas chromatography using an electron
capture detector. We have expanded
Methods 8080/8081 to cover the 45
compounds presented in Table 2.
Standards of these 45 organochlorine
pesticides were analyzed on two gas
chromatographic systems. One system
was equipped with a J&W Scientific
press-fit Y-shaped splitter, a 30-m x 0.53-
mm ID DB-5 column of 1.5-nm film
thickness, and a 30-m x 0.53-mm ID DB-
1701 column of 1.0-nm film thickness.
The other system was equipped with a
Supelco 8-in injection tee, a 30-m x 0.53-
mm ID DB-5 column of 0.83-nm film
thickness, and a 30-m x 0.53-mm ID DB-
1701 column of 1.0-nm film thickness.
The pairs that were co-eluting (com-
plete overlap) on the two columns using
the first system are identified as follows:
DB-5: trans-permethrin/heptachlor
epoxide
endosulfan l/alpha-chlordane
perthane/endrin
endosulfan ll/chloropropylate/
chlorobenzilate
p,p'-DDT/endosulfan sulfate
methoxychlor/dicofol
DB-1701: chlorothalonil/beta-BHC
delta-BHC/DCPA/trans-
permethrin
alpha-chlordane/trans-nonachlor
captan/dieldrin
chlorobenzilate/chloropropylate
With the thinner-film DB-5 column, a
different type of splitter, and the slower
temperature programming rate, fewer
compounds co-eluted on the DB-1701
column; however, on the DB-5 column
there were still 6 pairs co-eluting
(Table 2):
DB-5: diallate/alpha-BHC
perthane/endosulfan II
chlorobenzilate/chloropropylate
endrin/nitrofen
p,p'-DDT/endosulfan sulfate
methoxychlor/dicofol
DB-1701: alpha-chlordane/trans-nonachlor
(partially resolved)
p,p'-DDD/endosulfan II
(partially resolved)
Out of 10 compounds chromato-
graphed under the conditions established
for the organochlorine pesticides, a,a'-
dibromo-m-xylene was recommended as
the internal standard for the DB-5 (0.83-
pm film)/DB-1701 column pair, and 2-
bromobiphenyl was recommended as the
surrogate compound.
From the results of 10 consecutive
injections, we determined the retention
time reproducibility (percent RSD) to be
better than 0.54 percent for both col-
umns. The reproducibility of the detector
response for the DB-5 column was better
than 28.6 percent, with 32 of 43 values
being under 6 7 percent, and the
reproducibility of the detector response
on the DB-1701 column was better than
21.1 percent, with 29 of the 43 values
being under 5.6 percent.
The detector response for the DB-5
(0.83-nm film)/DB-1701 column pair was
linear for all target analytes from 10 pg to
100 pg per column, with linear correlation
coefficients being greater than 0.95 for all
compounds on the DB-5 column and for
26 out of 40 compounds on the DB-1701
column. Percent differences for RFs
determined one day after the gas
chromatographic system was calibrated
ranged from 17.7 to -37.8 percent for the
DB-5 column and from 33.4 to -45.8
percent for the DB-1701 column
indicating that the gas chromatographic
system requires daily calibration.
M'troaromaf/cs
Thirty-six nitroaromatic compounds
were determined on the DB-5/DB-1701
column pair (Table 3). By examining the
retention time data in Table 3, we
concluded that neither column can sep-
arate all 36 compounds. The co-eluting
compounds among the 36 test
compounds were:
DB-5: 2,4,6-trichloronitrobenzene/
1,3-dinitrobenzene
1 -chloro-2,4-dinitrobenzene/
1 -chloro-3,4-dinitrobenzene/
1,2,3-trichloro-4-nitrobenzene
DB-1701: 2,4-dichloronitrobenzene/
4-chlpro-3-nitrotoluene
2,4,6-trichloronitrobenzene/
1,4-naphthoquinone
1-chloro-2,4-dinitro-
benzene/2,3,4,5-tetra-
chloronitrobenzene
In addition, on the DB-5 column 2,5-
dichloronitrobenzene partially overlapped
with 4-chloro-3-nitrotoluene and trifluralin
partially overlapped with benefin. On the
DB-1701 column, compounds that par-
tially overlapped include p-nitrotoluene/1-
chloro-3-nitrobenzene and trifluralin/
benefin.
Out of 22 compounds, hexachloro-
benzene was selected as the internal
standard and 1-chloro-3-nitrobenzene
was selected as the surrogate compound.
From the results of 10 consecutive
injections, we determined the retention
time reproducibility (percent RSD) to be
better than 0.22 percent for both
columns, with most values less than 0.07
percent. The reproducibility of the
detector response was better than 9.4
percent on the DB-5 column, with the
exception of 1,2,3-trichloro-4-nitroben-
zene, 1-chloro-2,4-nitrobenzene and 1-
chloro-3,4-dinitrobenzene which were co-
eluting on the DB-5 column and for which
the RSD was 10.56 percent. The
reproducibility of the detector response
for the DB-1701 column was better than
9.13 percent for all target compounds.
The detector response was linear for
all target analytes in the 25- to 500-pg
range, with correlation coefficients
greater than 0.99 for 33 out of the 36
compounds on the DB-5 column. The
correlation coefficients for the DB-1701
column were greater than 0.99 for all
compounds, with the exception of 2,4,6-
trichloronitrobenzene and 1,4-naphtho-
quinone, which coelute, and 1-chloro-3,4-
dinitrobenzene. Percent differences for
RFs determined on consecutive days
indicate that the gas chromatographic
system requires daily calibration.
Haloethers
Nineteen haloethers were determined
on the DB-5/DB-1701 column pair each
connected to an electron capture detector
-------
Table 2. Retention Times of the Organochlorine Pesticides9
Compound
No. Compound CAS No.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
14
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
ISd
SUd
DBCP
Hexachlorocyclopentadiene
Etridiazole
Chloroneb
Hexachlorobenzene
Diallate
Propachlor
Trifluralin
alpha-BHC
PCNB
garnma-BHC
Heptachlor
Aldrin
Alachlor
Chlorothalonil
Alachlor
beta-BHC
Isodrin
DCPA
delta-BHC
Heptachlor epoxide
Endosulfan 1
gamma-Chlordane
alpha-Chlordane
trans-Nonachlor
p,p'-DDE
Dieldrin
Captan
Perthane
Endrin
Chloropropylate
Chlorobenzilate
Nitrofen
33 p,p'-DDD
Endosulfan II
p,p'-DDT
Endrin aldehyde
Mirex
Endosulfan sulfate
Methoxychlor
Captafol
Endrin ketone
trans-Permethrin
Kepone
Dicofol
Dichlone
a,a-Dibromo-m-xylene
2-Bromobiphenyl
96-12-8
77-47-4
2593-15-9
2675-77-6
118-74-1
2303-16-4
1918-16-17
1582-09-8
319-84-6
82-68-8
58-89-9
76-44-8
309-00-2
15972-60-8
1897-45-6
15972-60-8
319-85-7
465-73-6
1861-32-1
319-86-8
1024-57-3
959-98-8
5103-74-2
5103-71-9
39765-80-5
72-55-9
60-57-1
133-06-2
72-56-0
72-20-8
b
510-15-6
1836-75-5
72-54-8
33213-65-9
50-29-3
7421-93-4
2385-85-5
1031-07-8
72-43-5
2425-06-1
53494-70-5
51877-74-8
143-50-0
115-32-2
117-80-6
b
b
DB-5
RT(min)
2.14
4.49
6.38
7.46
12.79
12.35
9.96
11.87
12.35
14.47
14.14
18.34
20.37
18.58
15.81
18.58
13.80
22.08
21.38
15.49
22.83
25.00
24.29
25.25
25.58
26.80
26.60
23.29
28.45
27.86
28.92
28.92
27.86
29.32
28.45
31.62
29.63
37.15
31.62
35.33
32.65
33.79
41.50
31.10
35.33
15.17
9.17
8.54
DB-1701
RT(min)
2.84
4.88
8.42
10.60
14.58
15.07
15.43
16.26
17.42
18.20
20.00
21.16
22.78
24.18
24.42
24.18
25.04
25.29
26.11
26.37
27.31
28.88
29.32
29.82
30.01
30.40
31.20
31.47
32.18
32.44
34.14
34.42
34.42
35.32
35.51
36.30
38.08
38.79
40.05
40.31
41.42
42.26
45.81
c
c
c
11.51
12.49
a The GC operating conditions were as follows: 30-m x 0.53-mm ID DB-5 (O.83-fim film
thickness) and 30-m x 0.53-mm ID DB-1701 (1.0-fim film thickness) connected to an 8-ln
injection tee (Supelco Inc.). Temperature program: 140°C (2-min hold) to 270°C (1-min
hold) at 2.8°C/min; injector temperature 250°C; detector temperature 320°C; helium
carrier gas 6 mUmin; nitrogen makeup gas 20 mL/min.
b Not available.
c IS = internal standard; SU = surrogate compound.
-------
using the gas chromatographic conditions
given in Table 4. By examining the data
in Table 4, we concluded that the best
separation of the 19 compounds was
achieved on the DB-1701 column. The
elution order of the 19 compounds on the
two columns was identical, with the
exception of 2,4-dichlorophenyl-3'-meth-
yl-4'-nitrophenyl ether. The co-eluting
compounds on the DB-5 column were:
DB-5: 3,5-dichlorophenyl-4'-
nitrophenyl ether
3,4,5-trichlorophenyl-4'-
nitrophenyl ether
2,5-dichlorophenyl-4'-
nitrophenyl ether
2,4-dichlorophenyl-3'-methyl-4'-
nitrophenyl ether
On the DB-1701, 3,5-dichlorophenyl-
4'-nitrophenyl ether was partially resolved
from 2,5-dichlorophenyl-4'-nitrophenyl
ether, and 2,3,6-trichlorophenyl-4'-nitro-
phenyl ether was partially resolved from
2,3,5-trichlorophenyl-4'-nitrophenyl ether.
So far, we have not experienced any
problems in detecting the two pairs that
were only partially resolved.
Out of 10 compounds evaluated as
possible internal standards and sur-
rogates, 4,4'-dibromobiphenyl was rec-
ommended as the internal standard, and
2,4-dichlorodiphenyl ether and 2,3,4-
trichlorodiphenyl ether were recom-
mended as the surrogate compounds.
From the results of 10 consecutive
injections, we determined the retention
time reproducibility (percent RSD) to be
better than 0.12 percent for the DB-5
column, and better than 0.06 percent for
the DB-1701 column. The reproducibility
of the detector response was better than
2.4 percent on the DB-5 column and 1.55
percent or better on the DB-1701 column
for all target compounds.
The detector response was linear for
all target analytes in the 50- to 400-pg
range, with correlation coefficients
greater than 0.99 for all compounds on
the DB-5 column. The correlation
coefficients for the DB-1701 column were
greater than 0.99 for all compounds.
Percent differences for RFs determined
on two consecutive days after the gas
chromatographic system was calibrated
ranged from 19.2 to -0.93 percent on day
1 and from 0.61 to -15.5 percent on day 2
for the DB-5 column and from -2.24 to
-12.5 percent on day 1 and from -10.8 to
-20.4 percent on day 2 for the DB-1701
column indicating that the gas chromato-
graphic system requires daily calibration.
Chlorinated Hydrocarbons
Twenty-two chlorinated hydrocarbons
(Table 5) were determined on the
DB-5/DB-1701 column pair with dual-ECD
using the temperature program given in
Table 5. By examining the data in Table
5, we concluded that neither column can
separate all target analytes. The co-
eluting compounds among the 22 test
compounds were:
DB-5: 1,4-dichlorobenzene/benzyl
chloride
1,2,3,5-tetrachlorobenzene/
1,2,4,5-tetrachlorobenzene
1,2,3,4-tetrachlorobenzene/2-
chloronaphthalene
DB-1701: benzyl chloride/1,2-
dichlorobenzene/
hexachloroethane
benzal chloride/1,2,4-
trichlorobenzene/hexachloro-
butadiene
Out of 10 compounds evaluated as
possible internal standards and
surrogates, 1,3,5-tribromobenzene was
recommended as the internal standard
and 1,4-dichloronaphthalene was recom-
mended as the surrogate compound.
From the results of 10 consecutive
injections, we determined the retention
time reproducibility (percent RSD) to be
equal to or better than 0.08 percent for
both columns. The reproducibility of the
detector response was better than 11.1
percent on the DB-5 column and that for
the DB-1701 column was better than 17.1
percent for all compounds.
The method linearity was determined
for two sets of calibrations and the results
were compared. The first calibration
covered a range from 50 to 250 pg. The
detector response was linear, with
correlation coefficients being greater than
0.97 for the DB-5 column and between
0.83 and 0.99 for the DB-1701 column.
The second calibration was only per-
formed for the DB-1701 column and
covered the range between 50 pg and
125 pg. Linear correlation coefficients
were 0.99 for most compounds. The daily
variation of compound RFs was deter-
mined one day after the multilevel calib-
ration. The daily variation was below 10
percent for most compounds on the DB-5
column, and below 20 percent for most
compounds on the DB-1701 column.
Organophosphorus Pesticides
Preliminary experiments to chromato-
graph the 50 compounds listed in Table 6
were performed with a DB-5/DB-1701
column pair and nitrogen/phosphorus
detectors. Because of excessive back-
ground noise, the DB-1701 column was
replaced with a DB-210 column. All
experiments were then carried out with
the DB-5/DB-210 column pair and two
nitrogen phosphorus detectors. By exam-
ining the data in Table 6, we concluded
that neither column can resolve all 50
compounds. The co-eluting compounds
were:
DB-5: terbufos/tricresyl phosphate
naled/simazine/atrazine
dichlorophenthion/demeton-O
trichloronate/aspon
bolstar/stirophos/
carbophenothion
phosphamidon/crotoxyphos
fensulfothipn/EPN
DB-210: terbufos/tricresyl phosphate
dichlorophenthion/
phosphamidon
chlorpyrifos methyl/
parathion methyl
chlorpyrifos/parathion ethyl
aspon/fenthion demeton-
0/dimethoate
leptophos/azinphos methyl
EPN/phosmet
famphur/carbophenothion
Out of 17 compounds tested for
suitability as internal standards and
surrogates, 1-bromo-2-nitrobenzene was
suggested as the internal standard, and
4-chloro-3-nitrobenzotrifluoride as the
surrogate.
From the results of 10 consecutive
injections, we determined the retention
time reproducibility (percent RSD) to be
better than 0.38 percent for the DB-5
column and better than 0.57 percent for
the DB-210 column. The reproducibility
of the detector response was better than
12.1 percent on the DB-5 column and
better than 13.5 percent on the DB-210
column for all 50 compounds.
The detector response was linear for
all the target analytes from 1 to 10 ng per
column, with correlation coefficients
greater than 0.95 for most of the com-
pounds on both columns. The daily varia-
tion of detector RFs were determined one
day and two days after the multilevel
calibration was performed. The daily
variation of the detector response was
less than 20 percent for most of the
compounds on both columns. However, a
few compounds showed significantly
higher deviations from linearity. Also, the
deviation from linearity was higher on the
second day.
Method Evaluation
Two aspects of the dual-column/dual-
detector method were addressed in this
study. One aspect dealt with how well the
target analytes were identified and
-------
Compour
No.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
IS<<
id
Compound
Nitrobenzene
o-Nitrotoluene
m-Nitrotoluene
p-Nitrotoluene
1 -Chloro-3 nitrobenzene13
1 -Chloro-4-nitrobenzene
1 -Chloro-2 -nitrobenzene
2-Cbloro-6-nitrotoluene
4-Chioro-2 -nitrotoluene
3, 5 -Dichioronitrobenzene
2,5-Dichioronitrobenzene
2,4-Dichloronitrobenzene
4-Cbloro-3-nitrotoluene
3,4-Dicbloronitrobenzene
2,3-Dichloronitrobenzene
2, 4, 6-Trichloronitrobenzene
1,4-Naphthoquinone
1,2,4-Trichloro-5-nitrobenzene
1 , 4 -Dmitrobenzene
2, 6-Dinitrotoluene
1 , 3 -Dinitrobenzene
l,,2,3-Trichloro-4-nitrobenzene
2,3,5,6-Tetracbloronitrobenzene
1 ,2 -Dinitrobenzene
2,4-Dmitrotoluene
1 -Chloro-2, 4-dinitrobenzene
2, 3,4,5-Tetrachloronitrobenzene
1 -Chloro-3, 4-dinitrobenzene
Trifluralin
Benefin
Pentachloronitrobenzene
Profluralin
Dmitramine
Butralin
Isopropalin
Penoxal/n (Pendimethalin)
Hexchlorobenzene
CAS No.
95-95-3
88-72-2
99-08-1
99-99-0
121-73-3
100-00-5
88-73-3
83-42-1
89-59-8
618-62-2
89-61-2
611-06-3
89-60-1
99-54-7
3209-22-1
c
130-15-4
89-69-0
100-25-4
606-20-2
99-65-0
17700-09-3
117-18-0
528-29-0
121-14-2
97-00-7
c
610-40-2
1582-09-8
1861-40-1
82-68-8
26399-36-0
29091-05-2
33629-47-9
33820-53-0
40318-45-4
118-74-1
DB-5
RT(min)
4.71
6.08
6.93
7.35
7.66
7.9
8.09
9.61
9.76
10.42
11.46
11.73
11.31
12.24
12.58
13.97
12.98
15.97
13.41
14.44
13.97
17.61
19.41
14.76
16.92
17.85
21.51
17.85
21.81
21.94
25.13
25.39
26.45
32.41
32.71
33.05
23.18
DB-1701
RT(min)
4.23
5.32
6.22
6.73
6.85
7.15
7.78
8.32
8.62
8.84
10.62
10.84
10.84
11.04
12.01
12.31
12.31
14.46
14.72
15.16
15.68
16.51
17.11
17.51
18.16
19.55
19.55
19.85
20.31
20.46
22.33
23.81
27.06
31.03
31.33
31.67
18.72
a The GC operating conditions were as follows: 30-m x 0.53-mm ID DB-5 (1.5-nm film
thickness) and 30-m x 0.53-mm ID DB-1701 (I.O-nm film thickness) connected to a J&W
Scientific press-fit Y-shaped Inlet splitter. Temperature program: 120°C (1-min hold) to
200°C (1-min hold) at 3°C/min then to 250°C (4-min hold) at 8°C/min; injector temperature
250°C; detector temperature 320°C: helium carrier gas 6 mUmin; nitrogen makeup gas 20
mL/min.
b Recommended as surrogate compound.
c Not available.
dIS = internal standard.
quantified by the dual-column/dual-
detector approach when no matrix inter-
ferents were present. For this purpose,
we selected a set of blind performance
evaluation samples which were available
from EPA-Cincinnati and contained not
only the target analytes but also other
compounds of environmental signif-
icance. The other aspect dealt with how
well the target analytes were identified
and quantified by the dual-column/dual-
detector approach in real matrix extracts.
For this purpose, we prepared a few
matrix extracts (mostly from soils
contaminated with pesticides), spiked
these extracts with known amounts of the
target analytes, and analyzed the spiked
extracts
The samples that we were able to
obtain contained only a limited number of
the target phenols and of the target
chlorinated hydrocarbons. For example,
EPA WP-281 Sample 2 was reported to
contain 9 phenols at levels ranging from
8.3 to 20 ng/pL, and EPA WP-281
Sample 4 was reported to contain the
same compounds but at higher levels
(70.0 to 175 ng/pL). Using the DB-5/DB-
1701 column pair, we were able to
identify all 9 compounds correctly. The
-------
Compour
No.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
/S*
sty- 7*
SU-2*>
id
Compound
4-Bromophenyl-phenyl ether
Phenyl-4 '-nitrophenyl ether
2-Chlorophenyl-4 'nitrophenyl ether
3-Chlorophenyl-4 '-nitrophenyl ether
4-Chlorophenyl-4 '-nitrophenyl ether
2,6-Dichlorophenyl-4 '-nitrophenyl ether
3,5-Dichlorophenyl-4 '-nitrophenyl ether
2,5-Dichlorophenyl-4 '-nitrophenyl ether
2,4-Dichlorophenyl-4 '-nitrophenyl ether
2,3-Dichlorophenyl-4 '-nitrophenyl ether
3,4-Dichlorophenyl-4 '-nitrophenyl ether
2,4,6-Trichlorophenyl-4 '-nitrophenyl ether
2,3,6-Trichlorophenyl-4 '-nitrophenyl ether
2,3,5-Trichlorophenyl-4 'nitrophenyl ether
2,4,5-Thchlorophenyl-4 '-nitrophenyl ether
2,4-Dibromophenyl-4 '-nitrophenyl ether
3,4,5-Trichlorophenyl-4 '-nitrophenyl ether
2,3,4-Trichlorophenyl-4 'nitrophenyl ether
2, 4-Dichlorophenyl-3 '-methyl -4 '-nitrophenyl ether
4, 4 '-Dibromobiphenyl
2,4-Dichlorodiphenyl ether
2,3,4-Trichlorodiphenyl ether
DB-5
RT(min)
4.28
6.85
10.44
10.78
11.37
14.02
14.55
14.55
15.08
16.11
16.65
17.89
19.40
19.70
20.03
21.63
21.83
22.28
21.83
9.44
4.82
8.31
DB-1701
RT(min)
5.57
10.86
16.31
16.70
17.68
20.84
21.33
21.54
22.30
23.87
24.54
24.93
27.27
27.56
28.05
30.03
30.42
31.18
31.60
12.66
6.17
10.95
a The GC operating conditions were as follows: 30-m x 0.53-mm ID DB-5 (0.83-^n film
thickness) and 30-m x 0.53-mm ID DB-1701 (1.0-fim film thickness) connected to an 8-in
injection tee (Supelco Inc.). Temperature program: 180°C (0.5-min hold) to 260"C (1.0-min
hold) at 2°C/min injector temperature 250°C; detector temperature 320°C; helium carrier gas
6 mUmin; nitrogen makeup gas 20 mL'min. CAS Registry numbers are not available for any of
these compounds.
b IS = internal standard; SU = surrogate compound.
percent biases are satisfactory consid-
ering the fact that the samples had to be
diluted and then derivatized with PFBBr
prior to the GC/ECD analysis.
Five blind performance evaluation
samples were available for the chlor-
inated hydrocarbons. Two of these
samples were reported to contain com-
pounds such as nitroaromatics, phthalate
esters, polynuclear aromatic hydro-
carbons, etc. The four chlorinated hydro-
carbons that were present in EPA WP-
186 Sample 3 were identified correctly.
Pentachlorobenzene was not confirmed
in WP-286 Sample 1 (although it was
reportedly to be present in the sample).
The results from 6 different, spiked
matrix extracts showed that all
compounds were identified correctly,
even when matrix interferents were
present in the sample. This further
indicates that compound retention times
were reproducible and that any
nonvolatile residue that might have been
present in these matrix extracts did not
cause any problems during sample
injection. Biases were quite high in the
case of the organochlorine pesticides,
possibly because the extracts had to be
subjected to diol cartridge cleanup prior
to gas chromatographic analysis. Further-
more, the Matrix 1 and 2 extracts
contained high levels of endrin, endo-
sulfan II, and p,p'-DDT. Since the spiking
levels were significantly lower than the
background levels for these three
compounds, the errors had to be quite
high.
Conclusion
The results of this study indicate that
the dual-column/dual-detector approach
using two 30-m x 0.53-mm ID fused-silica
open-tubular columns coated with dissim-
ilar stationary phases and connected to
either an 8-in injection tee or a press-fit
Y-shaped splitter is reliable for the gas
chromatographic determination of Meth-
od 8040 phenols, Methods 8080/8081
organochlorine pesticides, Method 8090
nitroaromatics, Method 8110 haloethers,
Method 8120 chlorinated hydrocarbons,
and Method 8140/8141 organophos-
phorus pesticides.
The lists of compounds targeted by
the methods identified in this study have
been expanded to cover additional iso-
mers of the target compounds, and
internal standards and surrogate com-
pounds have been selected for each
method.
Blind performance evaluation samples
and matrix extracts of environmental
samples (spiked with the target analytes)
were analyzed by the dual-column/dual-
detector procedure to establish how well
the target analytes are identified and
quantified in the presence of matrix
interferents.
Notice
Although the research described in
this paper has been supported by the
U.S. Environmental Protection Agency, it
has not been subjected to Agency review
and therefore does not necessarily reflect
the views of the Agency, and no official
endorsement should be inferred. Mention
of trade names or commercial products
does not constitute endorsement or
recommendation for use.
-------
Table 5. Retention Times of the Chlorinated Hydrocarbons8
Compound
No.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
IS*
SUb
Compound
1 , 3 -Dichlorobenzene
1 , 4 -Dichlorobenzene
Benzyl chloride
1,2-Dichlorobenzene
Hexachloroethane
1,3,5-Trichlorobenzene
Benzal chloride
1,2,4-Trichlorobenzene
1,2,3. Trichlorobenzene
Hexachlorobutadiene
Benzotrichloride
1,2,3,5-Tetrachlorobenzene
1,2,4,5- Tetrachlorobenzene
Hexachlorocyclopentadiene
1,2,3,4-Tetrachlorobenzene
2-Chloronaphthalene
Pentachlorobenzene
alpha-BHC
Hexachlorobenzene
beta-BHC
gamma-BHC
delta-BHC
1,3,5-Tribromobenzene
1,4-Dichloronaphthalene
CAS No.
541-73-1
106-46-1
100-44-7
95-50-1
67-72-1
108-70-3
98-87-2
120-82-1
87-61-6
87-68-3
98-07-7
634-90-2
95-94-2
77-47-4
634-66-2
91-58-7
608-93-5
619-84-6
118-74-1
619-85-7
58-89-9
319-86-8
626-39-1
c
DB-5
RT(min)
5.82
600
6.00
6.64
791
10.07
10.27
11.97
13.58
13.88
14.09
19.35
19.35
1985
21 97
21.77
2902
34.64
34.98
3599
3625
37.39
11 83
15.42
DB-1701
RT(min)
7.22
7.53
8.47
8.58
8.58
11.55
14.41
14.54
16.93
14.41
17.12
21.85
22.07
21.17
25.71
26.60
31.05
38.79
36.52
43.77
40.59
44.62
13.34
17.71
a The GC operating conditions were as follows: 30-m x 0.53-mm ID DB-5 (0.83-pjv film
thickness) and 30-m x 0.53-mm ID DB-1701 (1.0-yjri film thickness) connected to an 8-
m injection tee (Supelco Inc.). Temperature program: 80°C (1.5-min hold) to 125°C
(1-min hold) at 2°dmin then to 240°C (2-min hold) at 5°C/min; injector temperature
250°C, detector temperature 320 'C; helium carrier gas 6 mL/min; nitrogen makeup
gas 20 mL/mm.
b IS = internal standard; SU = surrogate compound.
c Not available.
-------
Table 6. Retention Times of the Organophosphorus Pesticides8
Compound
No. Compound CAS No
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
IS'
SI/
Trimethylphosphate
Dichlorvos
Hexamethylphosphoramide
Trichlorfon
TEPP
Thionazin
Mevinphos
Ethoprop
Diazinon
Sulfotepp
Terbufos
Tricresyl phosphate
Naled
Phorate
Fonophos
Disulfoton
Merphos
Dichlorofenthion
Chlorpyrifos -methyl
Ronnel
Chlorpyrifos
Trichloronate
Aspon
Fenthion
Demeton-S
Demeton-O
Monochrotophos
Dimethoate
Tokuthion
Malathion
Parathion -methyl
Fenithrothion
Chlorfevinphos
Parathion -ethyl
Bo/star
Stirophos
Ethion
Phosphamidon
Crotoxyphos
Leptophos
Fensulfothion
EPN
Phosmet
Azinphos-methyl
Azinphos-ethyl
Famphur
Coumaphos
Atrazined
Simazined
Carbophenothiond
Dioxathion
1 -Bromo-2-nitrobenzene
4-Chloro-3-nitrobenzotrifluohde
512-56-1
62-73-7
680-31-9
52-68-6
21646-99-1
297-97-2
7786-34-7
13194-48-4
333-41-5
3689-25-5
13071-79-9
78-30-8
300-76-5
298-02-2
944-22-9
298-04-4
150-50-5
97-17-6
5598-13-1
299-84-3
2921-88-2
327-98-0
3244-90-4
55-38-9
8065-48-3
8065-48-3
6923-22-4
60-51-5
34643-46-4
121-75-5
298-00-0
122-14-5
470-90-6
56-38-2
35400-43-2
22248-79-9
563-12-2
13171-21-6
7700-17-6
21609-90-5
115-90-2
2104-64-5
732-11-6
86-50-0
2642-71-9
52-85-7
56-72-4
1912-24-9
122-34-9
786-19-6
78-34-2
g
9
08-5
RT(min)
b
7.45
b
11.22
b
12.32
12.20
12.57
13.23
13.39
13.69
13.69
14.18
12.27
14.44
14.74
14.89
15.55
15.94
16.30
17.06
17.29
17.29
17.87
11.10
15.57
19.08
18.11
19.29
19.83
20.15
20.63
21.07
21.38
22.09
22.06
22.55
22.77
22.77
24.62
27.54
27.58
27.89
28.70
29.27
29.41
33.22
13.98
13.85
22.14
e
8.11
5.73
DB-210
RT(min)
2.36
6.99
7.97
11.63
13.82
14.71
10.82
15.29
18.60
16.32
18.23
18.23
15.85
16.57
18.38
18.84
23.22C
20.09
20.45
21.01
22.22
22.73
21.98
22.11
14.86
17.21
15.98
17.21
24.77
21.75
20.45
21.42
23.66
22.22
27.57
24.63
27.12
20.09
23.85
31.32
26.76
29.99
29.89
31.25
32.36
27.79
33.64
17.63
17.41
27.92
e
9.07
5.40
References
1. Test Methods for Evaluating Solid
Waste; Laboratory Manual - Phys-
ical/Chemical Methods, SW-846, 3rd
Edition, Vol 1B, U.S. Environmental
Protection Agency, Washington, DC,
November 1986.
2. Lee, H. B., Weng, L D., and Chau, A. S.
Y., "Cemical Derivatization Analysis of
Pesticide Residues. IX. Analysis of
Phenol and 21 Chlorinated Phenols in
Natural Waters by Formation of
Pentafluorobenzyl Ether Derivatives," J.
Assoc. Off. Anal. Chem. 41:375-387
1988.
a 'The GC operating conditions were as follows: 30-m x 0.53-mm ID DB- 5 (1.50-fim film
thickness) and 30-m x 0.53-mm ID DB-210 (1.0-tim film thickness) connected to a J&W
Scientific press-fit Y-shaped inlet splitter. Temperature program: 120°C (3-min hold) to
270°C (10- min hold) at 5aC/min; injector temperature 250°C: detector temperature 300°C-
bead temperature 400°C; bias voltage 4.0: hydrogen gas pressure 20 psi; helium carrier
gas 6 mL/min; helium makeup gas 20 mL/min.
b Not detected at 20 ng per injection.
c Merphos shows another peak at 20.25 min on DB-5 and 24.87 min on DB-210.
d Originally in the organochlorine pesticide list but were added to the Organophosphorus
pesticide list because they gave very poor detector responses when analyzed with an
electron capture detector.
e Shows multiple peaks.
' IS - internal standard; SU = surrogate compound.
9 Not available.
10
-------
-------
V. Lopez-Avila, E. Baldin, J. Benedicto, and J. Milanes are with Mid-Pacific
Environmental Laboratory, Mountain View, California 94043. W.F Beckert
(also the EPA Project Officer, see below) is with Environmental Monitorina
Systems Laboratory, Las Vegas, NV 89193-3478.
The complete report, entitled "Application of Open-Tubular Columns to SW-846
GC Methods," (Order No. PB 90-259 8471 AS; Cost: $39.00, 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
Las Vegas, NV 89193-3478
United States Center for Environmental Ftesearch
Environmental Protection Information
Agency Cincinnati OH 45268
Official Business
Penalty for Private Use $300
EPA/600/S4-90/021
------- |