METHOD 508.1
DETERMINATION OF CHLORINATED PESTICIDES, HERBICIDES, AND
ORGANOHALIDES BY LIQUID-SOLID EXTRACTION AND ELECTRON
CAPTURE GAS CHROMATOGRAPHY
James W. Eichelberger — Revision 1.0, 1994
ENVIRONMENTAL MONITORING SYSTEMS LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
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METHOD 508.1
DETERMINATION OF CHLORINATED PESTICIDES, HERBICIDES, AND
ORGANOHALIDES IN WATER USING LIQUID-SOLID EXTRACTION
AND ELECTRON CAPTURE GAS CHROMATOGRAPHY
SCOPE AND APPLICATION
1.1 This method utilizes disk liquid-solid extraction and gas chromatography with
an electron capture detector to determine twenty nine chlorinated pesticides,
three herbicides, and four organohalides in drinking water, ground water, and
drinking water in any treatment stage. Liquid solid extraction cartridges may
also be used to carry out sample extractions. Single laboratory accuracy,
precision, and method detection limit data have been determined for the
following compounds:
Analyte
Chemical Abstract Services
Registry Number
Alachlor
15972-60-8
Aldrin
309-00-2
Atrazine
1912-24-9
Chlordane-alpha
5103-71-9
Chlordane-gamma
5103-74-2
Chloroneb
2675-77-6
Chlorbenzilate
510-15-6
Chlorthalonil
1897-45-6
Cyanazine
21725-46-2
DCPA
1861-32-1
4,4'-DDD
72-54-8
4,4'-DDE
72-55-9
4,4'-DDT
50-29-3
Dieldrin
60-57-1
Endosulfan I
959-98-8
Endosulfan II
33213-65-9
Endosulfan sulfate
1031-07-8
Endrin
72-20-8
Endrin aldehyde
7421-93-4
Etridiazole
2593-15-9
HCH-alpha
319-84-6
HCH-beta
319-85-7
HCH-delta
319-86-8
HCH-gamma (lindane)
58-89-9
Heptachlor
76-44-8
Heptachlor epoxide
1024-57-3
Hexachlorobenzene
118-74-1
Hexachlorocyclopentadiene
77-47-4
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Analyte
Chemical Abstract Services
Registry Number
Methoxychlor
72-43-5
Metolachlor
51218-45-2
Metribuzin
21087-64-9
cis-Permethrin
54774-45-7
trans-Permethrin
51877-74-8
Propachlor
1918-16-7
Simazine
122-34-9
Trifluralin
1582-09-8
1.2 This method has been validated in a single laboratory and method detection
limits have been determined for each analyte listed above. The method
detection limit (MDL) is defined as the statistically calculated minimum
amount that can be measured with 99% confidence that the reported value is
greater than zero1. For the listed analytes, MDLs which range from
0.001-0.015 Hg/L are listed in Table 3.
2.0 SUMMARY OF METHOD
2.1 The analytes are extracted from the water sample by passing 1 L of sample
through a preconditioned disk or cartridge containing a solid inorganic matrix
coated with a chemically bonded C18 organic phase (liquid-solid extraction,
LSE). The analytes are eluted from the LSE disk or cartridge with small
volumes of ethyl acetate and methylene chloride, and this eluate is
concentrated by evaporation of some of the solvent. The sample components
are separated, identified, and measured by injecting micro-liter quantities of
the eluate into a high resolution fused silica capillary column of a gas
chromatograph/electron capture detector (GC/ECD) system.
3.0 DEFINITIONS
3.1 Internal Standard (IS) — A pure analyte(s) added to a sample, extract, or
standard solution in known amount(s) and used to measure the relative
responses of other method analytes and surrogates that are components of the
same solution.
3.2 Surrogate Analyte (SA) — A pure analyte(s), which is extremely unlikely to be
found in any sample, and which is added to a sample aliquot in known
amount(s) before extraction or other processing, and is measured with the
same procedures used to measure other sample components. The purpose of
the SA is to monitor method performance with each sample.
3.3 Laboratory Reagent Blank (LRB) — A aliquot of reagent water or other blank
matrix that is treated exactly as a sample including exposure to all glassware,
equipment, solvents, reagents, internal standards, and surrogates that are used
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with other samples. The LRB is used to determine if method analytes or other
interferences are present in the laboratory environment, the reagents, or the
apparatus.
3.4 Instrument Performance Check Solution (IPC) — A solution of one or more
method analytes, surrogates, internal standards, or other test substances used
to evaluate the performance of the instrument system with respect to a defined
set of method criteria.
3.5 Laboratory Fortified Blank (LFB) — An aliquot of reagent water or other blank
matrix to which known quantities of the method analytes are added in the
laboratory. The LFB is analyzed exactly like a sample, and its purpose is to
determine whether the methodology is in control, and whether the laboratory
is capable of making accurate and precise measurements.
3.6 Laboratory Fortified Sample Matrix (LFM) — An aliquot of an environmental
sample to which known quantities of the method analytes are added in the
laboratory. The LFM is analyzed exactly like a sample, and its purpose is to
determine whether the sample matrix contributes bias to the analytical results.
The background concentrations of the analytes in the sample matrix must be
determined in a separate aliquot and the measured values in the LFM
corrected for background concentrations.
3.7 Stock Standard Solution (SSS) — A concentrated solution containing one or
more method analytes prepared in the laboratory using assayed reference
materials or purchased from a reputable commercial source.
3.8 Primary Dilution Standard Solution (PDS) — A solution of several analytes
prepared in the laboratory from stock standard solutions and diluted as
needed to prepare calibration solutions and other needed analyte solutions.
3.9 Quality Control Sample (QCS) — A solution of method analytes of known
concentrations which are used to fortify an aliquot of LRB or sample matrix.
The QCS is obtained from a source external to the laboratory and different
from the source of calibration standards. It is used to check laboratory
performance with externally prepared test materials.
3.10 Method Detection Limit (MDL) — The statistically calculated minimum amount
of an analyte that can be measured with 99% confidence that the reported
value is greater than zero1.
INTERFERENCES
4.1 Method interferences may be caused by contaminants in solvents, reagents,
glassware, and other sample processing apparatus that lead to anomalous
peaks or elevated baselines in gas chromatograms.
4.2 Interfering contamination may occur when a sample containing low
concentrations of compounds is analyzed immediately after a sample
containing relatively high concentrations of compounds. Syringes and splitless
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injection port liners must be cleaned carefully or replaced as needed. After
analysis of a sample containing high concentrations of compounds, a
laboratory reagent blank should be analyzed to ensure that accurate values are
obtained for the next sample.
5.0 SAFETY
5.1 The toxicity or carcinogenicity of each chemical and reagent used in this
method has not been precisely defined. However, each one must be treated as
a potential health hazard, and exposure to these chemicals should be
minimized. Each laboratory is responsible for maintaining a current awareness
of OSHA regulations regarding safe handling of the chemicals used in this
method. Additional references to laboratory safety are cited2 4.
5.2 Some method analytes have been tentatively classified as known or suspected
human or mammalian carcinogens. Pure standard materials and stock
standard solutions of these compounds should be handled with suitable
protection to skin, eyes, etc.
6.0 EQUIPMENT AND SUPPLIES
6.1 All glassware, including sample bottles, must be meticulously cleaned. This
may be accomplished by washing with detergent and water, rinsing with tap
water, distilled water, or solvent, air-drying, and heating (where appropriate)
in a muffle furnace for two hours at 400°C. Volumetric glassware must never
be heated in a muffle furnace.
6.2 Sample Containers — 1 L or 1 qt amber glass bottles fitted with Teflon-lined
screw caps. Amber bottles are highly recommended since some of the method
analytes are sensitive to light and are oxidized or decomposed upon exposure.
6.3 Volumetric Flasks — Various sizes.
6.4 Micro-syringes — Various sizes.
6.5 Vials — Various sizes of amber vials with Teflon-lined screw caps.
6.6 Drying Column — The drying tube should contain about 5-7 g of anhydrous
sodium sulfate to prohibit residual water from contaminating the extract. Any
small tube may be used, such as a syringe barrel, a glass dropper, etc., as long
as no sodium sulfate passes through the column into the extract.
6.7 Fused Silica Capillary Gas Chromatography Column — Any capillary column
that provides adequate resolution, capacity, accuracy, and precision may be
used. A 30 m x 0.25 mm ID fused silica capillary column coated with a
0.25 |im bonded film of polyphenylmethylsilicone (J&W DB-5) was used to
develop this method. Any column which provides analyte separations
equivalent to or better than this column may be used.
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6.8 Gas Chromatograph — Must be capable of temperature programming, be
equipped for split/splitless injection, and be equipped with an electron capture
detector. On-column capillary injection is acceptable if all the quality control
specifications in Sections 9.0 and 10.0 are met. The injection tube liner should
be quartz and about 3 mm in diameter. The injection system should not allow
the analytes to contact hot stainless steel or other hot metal surfaces that
promote decomposition.
6.9 Vacuum Manifold — A manifold system or a commercially available automatic
or robotic sample preparation system designed for disks or cartridges should
be utilized in this method. Ensure that all quality control requirements
discussed in Section 9.0 are met. A standard all glass or Teflon lined filter
apparatus should be used for disk or cartridge extraction when an automatic
system is not utilized.
REAGENTS AND STANDARDS
7.1 Helium Carrier Gas — As contaminant free as possible.
7.2 Extraction Disks and Cartridges — Containing octadecyl bonded silica
uniformly enmeshed in an inert matrix. The disks used to generate the data in
this method were 47 mm in diameter and 0.5 mm in thickness. Larger disk
sizes are acceptable. The disks should not contain any organic compounds,
either from the matrix or the bonded silica, that will leach into the ethyl
acetate and methylene chloride eluant. Cartridges should be made of inert,
non-leaching plastic or glass, and must not leach plasticizers or other organic
compounds into the eluting solvent. Cartridges contain about 1 g of silica or
other inert inorganic support whose surface is modified by chemically bonding
octadecyl C18 groups.
7.3 Solvents — Methylene chloride, ethyl acetate, and methanol, high purity
pesticide quality or equivalent.
7.4 Reagent Water — Water in which an interferant is not observed at the MDL of
the compound of interest. Prepare reagent water by passing tap or distilled
water through a filter bed containing activated carbon, or by using a water
purification system. If necessary, store reagent water in clean bottles with
Teflon-lined screw caps.
7.5 Hydrochloric Acid — 6 N.
7.6 Sodium Sulfate — Anhydrous, muffled at 450°C for a minimum of four hours
and stored in an air-tight clean glass container at ambient temperature.
7.7 Sodium Sulfite — Anhydrous.
7.8 Pentachloronitrobenzene — >98% purity, for use as the internal standard.
7.9 4,4-Dibromobiphenyl — >96% purity, for use as the surrogate compound.
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7.10 Stock Standard Solutions — Individual solutions of analytes may be purchased
from commercial suppliers or prepared from pure materials. These solutions
are usually available at a concentration of 500 jig/mL. These solutions are
used to make the primary dilution standard. They should be stored in amber
vials in a refrigerator or freezer. Stock standard solutions should be replaced if
ongoing quality control checks indicate a problem.
7.11 Primary Dilution Standards — Prepare the solution(s) to contain
all method analytes, but not the internal standard or surrogate compound, at a
concentration of 2.5 jig/mL in ethyl acetate.
7.12 Instrument Performance Check Solution — Prepare by accurately weighing
0.0010 g each of chlorothalonil, chlorpyrifos, DCPA, and HCH-delta. Dissolve
each analyte in MTBE and dilute to volume in individual 10-mL volumetric
flasks. Combine 2 jiL of the chlorpyrifos stock solution, 50 jiL of the DCPA
stock solution, 50 jiL of the chlorothalonil stock solution, and 40 jiL of the
HCH-delta stock solution to a 100 mL volumetric flask and dilute to volume
with ethyl acetate. Transfer to a TFE-fluorocarbon-sealed screw cap bottle and
store at room temperature. Solution should be replaced when ongoing QC
(Section 9.0) indicates a problem.
7.13 Calibration Solutions — Using the primary dilution standards, prepare
calibration solutions at six concentrations in ethyl acetate. The calibration
range is dependent upon the instrumentation used, and expected analyte
concentrations in the samples to be analyzed. A suggested concentration range
of calibration solutions is 0.002-1.0 jig/mL.
7.14 Internal Standard Solution — Prepare this solution of pentachloronitrobenzene
by itself in ethyl acetate at a concentration of 10 jig/mL.
7.15 Surrogate Compound Solution — Prepare this solution of 4,4'-dibromobiphenyl
by itself in ethyl acetate at a concentration of 10 jig/mL. Other surrogate
compounds may be used if it can be demonstrated that they are not in any
samples and are not interfered with by any analyte or other sample
component.
7.16 GC Degradation Check Solution — Prepare a solution in ethyl acetate
containing endrin and 4,4'-DDT each at a concentration of 1 jig/mL. This
solution will be injected to check for undesirable degradation of these
compounds in the injection port by looking for endrin aldehyde and endrin
ketone or for 4,4'- DDE and 4,4'- DDD.
SAMPLE COLLECTION. PRESERVATION. AND STORAGE
8.1 When sampling from a water tap, open the tap and allow the system to flush
until the water temperature has stabilized (generally one to two minutes).
Adjust the flow to about 500 mL/min and collect the sample from the flowing
stream. Keep sample sealed from collection time until analysis. When
sampling from a body of water, fill the sample container with water from a
representative area. Sampling equipment, including automatic samplers, must
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not use plastic tubing, plastic gaskets, or any parts that may leach interfering
analytes into the sample. Automatic samplers that composite samples over
time should use refrigerated glass sample containers.
8.2 Residual chlorine in the sample should be reduced by adding 50 mg/L of
sodium sulfite (this may be added as a solid with stirring or shaking until
dissolved, or as a prepared solution).
8.3 Adjust the sample to pH <2 by adding 6N HC1. It may require up to 4 mL to
accomplish this. It is very important that the sample be dechlorinated
(Section 8.2) before adding the acid to lower the pH of the sample. Adding
sodium sulfite and HC1 to the sample bottles prior to shipping the bottles to
the sampling site is not permitted. HC1 should be added at the sampling site
to retard any microbiological degradation of method analytes.
8.4 Samples must be iced or refrigerated as close to 4°C as possible from the time
of collection until extraction. Preservation study results show that the analytes
(except cyanazine) are stable for 14 days in samples that are preserved as
described in Sections 8.2 and 8.3. Refrigerated sample extracts may be stored
up to 30 days.
8.5 If cyanazine is to be determined, a separate sample must be collected.
Cyanazine degrades in the sample when it is stored under acidic conditions or
when sodium sulfite is present in the stored sample. Samples collected for
cyanazine determination MUST NOT be dechlorinated or acidified when
collected. They should be iced or refrigerated as described above and
analyzed within 14 days. However, these samples must be dechlorinated and
acidified immediately prior to fortification with the surrogate standard and
extraction using the same quantities of acid and sodium sulfite described
above.
QUALITY CONTROL
9.1 Quality control requirements are the initial demonstration of laboratory
capability followed by regular analyses of laboratory reagent blanks, laboratory
fortified blanks, and laboratory fortified matrix samples. The laboratory must
maintain records to document the quality of the data generated. Additional
quality control practices are recommended.
9.2 Before any samples are analyzed or any time a new supply of disks or
cartridges are received from a supplier, it must be demonstrated that a
laboratory reagent blank is reasonably free of contamination that would
prevent the determination of any analyte of concern. Both disks and cartridges
could contain trace quantities of phthalate esters or silicon compounds that
could prevent the determination of method analytes at low concentrations.
Other sources of background contamination are impure solvents, impure
reagents, and contaminated glassware. In general, background from method
analytes should be below method detection limits.
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9.3 To demonstrate initial laboratory capability, analyze a minimum of four
replicate laboratory fortified blanks containing each analyte of concern at a
suggested concentration in the range of 0.01-0.5 Hg/L.
9.3.1 Prepare each reagent water replicate by adding sodium sulfite
(Section 8.2) and HC1 (Section 8.3) to each sample, then adding an
appropriate aliquot of the primary dilution standard solution (s).
Analyze each replicate according to the procedures described in
Section 11.0.
9.3.2 Calculate the measured concentration of each analyte in each replicate,
the mean concentration of each analyte in all replicates, the mean
accuracy (as mean percentage of true value) for each analyte, and the
precision (as relative standard deviation, RSD) of the measurements for
each analyte.
9.3.3 For each analyte, the mean accuracy, expressed as a percentage of the
true value, should be 70-130% and the RSD should be <30%.
9.3.4 Analyze a minimum of seven replicate laboratory fortified blanks which
have been fortified with all analytes of interest at approximately
0.01 Hg/L. Calculate the MDL of each analyte using the procedure
described in Section 13.21. It is recommended that these analyses be
carried out over a period of three or four days to produce more realistic
limits.
9.3.5 Develop a system of control charts to plot the precision and accuracy of
analyte and surrogate compound recoveries as a function of time.
Charting of surrogate compound recoveries, which are present in every
sample, will form a significant record of data quality. When surrogate
recovery from a sample, a LFB, or a LFM is <70% or >130%, check
calculations to locate possible errors, the fortifying solution for
degradation, and changes in instrument performance. If the cause
cannot be determined, reanalyze the sample. If the recovery still is
<70% or >130%, remedial action (Section 10.8) will likely be necessary.
9.4 The analyst should monitor the internal standard response (peak area units) of
all samples and LFBs during each work shift. The IS area should not deviate
from the latest continuing calibration check (Section 10.7) by more than 30%, or
from the initial calibration by more than 50%.
9.5 With each group or set of samples processed within a 12-hour work shift,
analyze a LRB to determine background contamination. Any time a new batch
of LSE disks or cartridges are received, or a new supply of reagents are used,
repeat Section 9.2.
9.6 With each group or set of samples processed within a 12-hour work shift,
analyze a LFB containing each analyte of interest at a concentration of
0.01-0.5 Hg/L. If more than 20 samples are included in a set, analyze a LFB for
every 20 samples. Use the criteria in Section 9.3.3 to evaluate the accuracy of
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the measurements. If acceptable accuracy cannot be achieved, the problem
must be located and corrected before additional samples are analyzed.
Maintain control charts to document data quality.
9.7 In an attempt to ascertain any detrimental matrix effects, analyze a LFM for
each type of matrix (i.e., tap water, ground water, surface water). This need
not be done with every group of samples unless matrices are vastly different.
The LFM should contain each analyte of interest at a concentration of
approximately 1.0 Hg/L.
9.8 At least quarterly, analyze a QCS from an external source. If measured analyte
concentrations are not of acceptable accuracy as described in Section 9.3.3,
check the entire analytical procedure to locate and correct the problem.
9.9 Numerous other quality control measures are incorporated into other parts of
this method, and serve to alert the analyst to potential problems.
10.0 CALIBRATION AND STANDARDIZATION
10.1 Demonstration and documentation of acceptable initial calibration are required
before any samples are analyzed and is required intermittently throughout
sample analysis as dictated by results of continuing calibration checks. After
initial calibration has been successfully accomplished, a continuing calibration
check is required each 12-hour work shift in which analyses are performed.
10.2 Establish GC operating parameters equivalent to those below:
Injector temperature — 250°C
Detector temperature — 320°C
Injection volume — 2 |iL, splitless for 45 seconds
Temperature program — Inject at 40°C and hold one minute.
— program at 20°C/min. to 160°C hold three minutes
— program at 3°C/min. to 275°C with no hold
— program at 20°C/min. to 310°C with no hold
Using the above conditions and the column in Section 6.7, the total run time is
about 50 minutes. The last eluting analyte is trans-permethrin which elutes at
267°C with a retention time of 45.4 minutes. Table 1 lists all method analytes
and their retention times using the above conditions. It should be noted that
some method analytes elute very close together. If there are unresolved peaks
using the above temperature program, the analyst should modify the program
to achieve resolution.
10.3 Instrument performance should be monitored each 12-hour work shift by
analysis of the IPC sample. The IPC sample contains compounds designed to
indicate appropriate instrument sensitivity, column performance (primary
column) and chromatographic performance. IPC sample components and
performance criteria are listed in Table 2. Inability to demonstrate acceptable
instrument performance indicates the need for reevaluation of the instrument
system.
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10.4 Inject the GC degradation check solution. Look for the degradation products
of 4,4'-DDT (4,4'-DDE and 4,4'-DDD) and the degradation products of endrin
(endrin aldehyde, EA and endrin ketone, EK). For 4,4'-DDT, these products
will elute just before the parent, and for endrin, the products will elute just
after the parent. If degradation of either DDT or endrin exceeds 20%,
resilanize the injection port liner and/or break off a meter from the front of the
column. The degradation check solution is required in each 12-hour workshift
in which analyses are performed.
% degrade Total DDT degradation peak area (DDE+DDD) x jqq
of 4,4'DDT Total DDT peak area (DDT+DDE +DDD) X
% degrade _ Total EA+EK peak area x
of endrin Total endrin+EA+EK peak area
NOTE: If the analyst can verify that 4,4 DDT, endrin, their breakdown
products, and the analytes in the IPC solution are all resolved, the IPC solution
and the GC degradation check solution may be prepared and analyzed as a
single solution.
10.5 Prepare calibration solutions containing all analytes of interest according to
Section 7.13 in ethyl acetate. Each standard must contain the internal
standard, pentachloronitrobenzene, at a concentration of 0.5 |ig/mL. The
surrogate should also be present in each solution at that concentration.
10.6 Analyze each calibration standard using the suggested conditions in
Section 10.2. Tabulate peak area versus concentration for each
compound and the internal standard.
Calculate the response factor (RF) for each analyte and the surrogate using the
following equation.
rf-HB!
(Ais) (Cs)
where: As = Response for the analyte.
Ais = Response for the internal standard.
Cis = Concentration of the internal standard Hg/L.
Cs = Concentration of the analyte to be measured Hg/L.
10.7 If the RF over the working range is constant (<30% RSD), the average RF can
be used for calculations. Alternatively, use the results to generate a linear
regression calibration for each analyte using response ratios (AS/AIS) vs. Cs.
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10.8 The linear regression calibration or RF must be verified on each work shift (not
to exceed 12 hours) by measuring one or more medium concentration
calibration standards. Calculate the RF for each analyte from the data
measured in the continuing calibration check. The RF for each analyte must be
within 30% of the mean value measured in the initial calibration. If a linear
regression calibration is being used, the calculated amount for each analyte
must be within 30% of the true value. If these conditions do not exist,
remedial action should be taken which may require recalibration.
10.9 The following are suggested remedial actions which may improve method
performance:
10.9.1 Check and adjust GC operating conditions and temperature
programming parameters.
10.9.2 Clean or replace the splitless injector liner. Silanize a cleaned or new
liner.
10.9.3 Break off a short portion of the GC column from the end near the
injector, or replace GC column. Breaking off a portion of the column
will somewhat shorten the analyte retention times.
10.9.4 Prepare fresh calibration solutions and repeat the initial calibrations.
10.9.5 Replace any components in the GC that permit analytes to come in
contact with hot metal surfaces.
11.0 PROCEDURE
11.1 Disk Extraction
11.1.1 This procedure was developed using the standard 47 mm diameter
disks. Larger disks (i.e., 90 mm) may be used if special matrix
problems are encountered. If larger disks are used, the washing solvent
volume is 15 mL and the elution solvent volumes are two 15 mL
aliquots.
11.1.2 Insert the disk into the filter apparatus or sample preparation unit.
Wash the disk with 5 mL of a 1:1 mixture of ethyl acetate (EtAC) and
methylene chloride (MeCl2) by adding the solvent to the disk, then
drawing it through very slowly to ensure adequate contact time
between solvent and disk. Soaking the disk may not be desirable when
disks other than Teflon are used.
11.1.3 Add 5 mL methanol to the disk and draw some of it through slowly.
A layer of methanol must be left on the surface of the disk which must
not be allowed to go dry from this point until the end of the sample
extraction. THIS IS CRITICAL FOR UNIFORM FLOW AND GOOD
ANALYTE RECOVERIES.
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11.1.4 Rinse the disk with 5 mL reagent water by adding the water to the disk
and drawing most through, again leaving a layer on the surface of the
disk.
11.1.5 Add 5 mL methanol to the sample and mix well. Mark the water
meniscus on the side of the sample bottle for later determination of
sample volume.
11.1.6 Add 50 |iL of the surrogate compound solution (Section 7.15) and shake
well.
11.1.7 Draw the sample through the disk while maintaining sufficient
vacuum. One liter of drinking water may pass through the disk in as
little as five minutes without reducing analyte recoveries. Drain the
entire sample from the container through the disk. Determine the
original sample volume by refilling the sample bottle to the mark with
tap water and transferring the water to a 1000 mL graduated cylinder.
Measure to the nearest 5 mL.
11.1.8 Dry the disk by drawing air or nitrogen through the disk for about
10 minutes.
11.1.9 Remove the filtration glassware, but do not disassemble the reservoir
and fritted base. Insert a collection tube into the vacuum manifold. If
a suction flask is being used, empty the water from the flask and insert
a suitable collection tube to contain the eluate. The only constraint on
the collection tube is that it fit around the drip tip of the fritted base.
Reassemble the apparatus.
11.1.10 Rinse the inside walls of the sample bottle with 5 mL EtAC then
transfer the solvent to the disk using a syringe or disposable pipet.
Rinse the inside walls of the glass filtration reservoir with this EtAC.
Draw the solvent through the disk very slowly to allow adequate
contact time between disk and solvent for good analyte recoveries.
11.1.11 Repeat the above step (Section 11.10) with 5 mL MeCl2.
11.1.12 Using the syringe or disposable pipet, rinse the filtration reservoir
with two 3 mL portions of 1:1 EtAc:MeCl2. Pour all combined eluates
through the drying tube containing about 5-7 g of anhydrous sodium
sulfate. Rinse the drying tube and the sodium sulfate with two 3 mL
portions of 1:1 EtAc/MeCl2. Collect all eluate and washings in a
concentrator tube.
11.1.13 Concentrate the extract to 0.8 mL under a gentle stream of nitrogen
while warming gently in a water bath or heating block. Rinse the
inside walls of the concentrator tube two or three times with EtAC
during concentration. Fortify the extract with 50 pL of the IS
fortifying solution (Section 7.14). Adjust the extract volume to 1.0 mL
with EtAc.
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11.1.14 Inject a 1 |iL or 2 |iL aliquot into the gas chromatograph using the GC
conditions used for initial calibration (Section 10.2). Table 1 lists
retention times for method analytes using these conditions.
11.1.15 Identify a method analyte in the sample extract by comparing its gas
chromatographic retention time to the retention time of the known
analyte in a reference standard chromatogram, a calibration standard,
or a laboratory fortified blank. If the retention time of the sample
peak is within the predefined retention time window, identification is
considered positive. The width of the retention time window used to
make identifications should be based on measurements of actual
retention time variations of standards during the course of a work
shift. It is suggested that three times the standard deviation of the
retention times obtained when the system is calibrated be used to
calculate the window. The experience of the analyst should be an
important factor in the interpretation of a gas chromatogram.
Confirmation may be performed by analysis on a second column, or if
concentrations are sufficient, by GC/MS.
11.2 Cartridge Extraction
11.2.1 This procedure may be carried out in the manual mode or in the
automatic mode using a robotic or automatic sample preparation
device. If an automatic system is used to prepare samples, follow the
manufacturer's instructions, but follow this procedure. If the manual
mode is used, the setup of the extraction apparatus described in EPA
Method 525.2s may be used.
11.2.2 Elute each cartridge with a 5 mL aliquot of ethyl acetate followed by a
5 mL aliquot of methylene chloride. Let the cartridge drain dry after
each flush. Then elute the cartridge with a 10 mL aliquot of methanol,
but DO NOT allow the methanol to elute below the top of the cartridge
packing. Add 10 mL of reagent water to the cartridge and elute, but
before the reagent water level drops below the top edge of the packing,
begin adding sample to the solvent reservoir.
11.2.3 Pour the water sample into the 2 L separatory funnel with the stopcock
closed, add 5 mL methanol and the surrogate standard, and mix well.
If a vacuum manifold is used instead of the separatory funnel, the
sample may be transferred directly to the cartridge after the methanol
and surrogate standard are added to the sample.
11.2.4 Drain the sample into the cartridge being careful not to overflow the
cartridge. Maintain the packing material in the cartridge immersed in
water at all times. After all the sample has passed through the LSE
cartridge, draw air or nitrogen through the cartridge for 10 minutes.
11.2.5 If the setup in Method 525.2s is being used, transfer the 125 mL solvent
reservoir and LSE cartridge to the elution apparatus. The same
reservoir is used for both apparatus. Rinse the inside of the separatory
508.1-14
-------
funnel and the sample jar with 5 mL ethyl acetate and elute the
cartridge with this rinse into the collection tube. Wash the inside of the
separatory funnel and the sample jar with 5 mL methylene chloride and
elute the cartridge, collecting the rinse in the same collection tube.
Small amounts of residual water from the sample container and the
LSE cartridge may form am immiscible layer with the eluate. Pass the
eluate through the drying column which is packed with approximately
5-7 g of anhydrous sodium sulfate and collect in a second tube. Wash
the sodium sulfate with at least 2 mL methylene chloride and collect in
the same tube. Proceed according to steps in Sections 11.1.13, 11.1.14,
and 11.1.15 above.
12.0 DATA ANALYSIS AND CALCULATIONS
12.1 Calculate the concentration (C) of the analyte in the sample using the response
factor (RF) determined in Section 10.5 and the equation below.
r , n * (As) ^
C Cug/L) =
(A.) (RF) (Vo)
where: As = Response for the parameter to be measured.
Ais = Response for the internal standard.
Is = Amount of internal standard added to each extract (|ig).
VQ = Volume of water extracted (L).
If a linear regression calibration is used, use the regression equation to
calculate the amount of analyte in the sample. All samples containing analytes
outside the calibration range must be diluted and reanalyzed. When diluting,
add additional internal standard to maintain its concentration at 0.5 /xg/mL in
the diluted extract.
13.0 METHOD PERFORMANCE
13.1 Method performance data was obtained using the GC column and conditions
described in Sections 6.7 and 10.2. Retention times are listed in Table 1. All
data presented here were obtained with the liquid-solid extraction disk option.
Previous method development research has shown no significant performance
differences between cartridges and disks. Method 525.2 shows comparative
recovery data for Method 508.1 analytes using both cartridges and disks.
13.2 Method detection limits (MDL) for all method analytes were determined by
analyzing seven reagent water samples which were fortified with the analytes
at a concentration of 0.01 Hg/L. The mean and standard deviation were
calculated for each analyte. The MDL was calculated by multiplying the
standard deviation by the students-t value for n-1 and a 99% confidence
interval1. The students-t value for seven replicates (n-l=6) is 3.143. The mean
recoveries and the standard deviations along with the MDLs are listed in
Table 3.
508.1-15
-------
13.3 Method accuracy and precision were determined by analyzing two sets of
eight reagent water samples fortified at approximately 5 and 10 times the
average MDL. The fortification concentrations for these samples were
calculated by averaging the analyte MDLs and multiplying that average by
5 and 10. Thus the concentrations used were 0.03 Hg/L and 0.048 Hg/L.
Results of these analyses are listed in Tables 4 and 5. An additional set of
samples was analyzed at approximately 20 times the average MDL
(0.096 Hg/L). This set of samples was extracted from an artificial matrix
containing lmg/L fulvic acid. The fulvic acid served to mimic the naturally
occurring organic material found in many water sources. The results of these
analyses are listed in Table 6.
13.4 Atrazine, hexachlorocyclopentadiene, and metribuzin appear to be problem
analytes. The recoveries of atrazine were 70.4, 74.9, and 71.9 mean percent at
0.03, 0.048, and 0.096 Hg/L respectively in fortified reagent water. This analyte
displays low peak response when compared to most of the other method
analytes, and requires manual peak area integration even at the 0.048 Hg/L
level. Hexachlorocyclopentadiene, while displaying relatively high peak
response, showed poor recovery. The resulting mean recoveries were 50.8,
52.6, and 21.7%, respectively for the three levels. It is suspected that the
higher volatility of hexachlorocyclopentadiene causes the problem. Very
careful, very slow nitrogen blowdown may produce higher recoveries of this
compound. Metribuzin was recovered poorly at 39.5, 67.7, and 40.7% for the
three data sets. However, this analyte has a somewhat greater peak response
than atrazine.
14.0 POLLUTION PREVENTION
14.1 This method utilizes the new liquid-solid extraction (LSE) technology to
remove the analytes from water. It requires the use of very small volumes of
organic solvent and very small quantities of pure analytes. This eliminates the
potential hazards to both the analyst and the environment that are present
when large volumes of solvents are used in conventional liquid-liquid
extractions.
14.2 For information about pollution prevention that may be applicable to
laboratory operations, consult "Less Is Better: Laboratory Chemical
Management for Waste Reduction" available from the American Chemical
Society's Department of Governmental Relations and Science Policy, 1155 16th
Street N.W., Washington, D.C. 20036.
15.0 WASTE MANAGEMENT
15.1 It is the laboratory's responsibility to comply with all federal, state, and local
regulations governing waste management, particularly the hazardous waste
identification rules and land disposal restrictions. The laboratory using this
method has the responsibility to protect the air, water, and land by minimizing
and controlling all releases from fume hoods and bench operations.
Compliance is also required with any sewage discharge permits and
regulations. For further information on waste management, consult "The
508.1-16
-------
Waste Management Manual for Laboratory Personnel," also available from the
American Chemical Society at the address in Section 14.2.
16.0 REFERENCES
1. J.A. Glaser, Foerst, D.L., McKee, G.D., Quave, S.A., and Budde, W.L. "Trace
Analyses for Wastewaters," Environ. Sci. Technol. 1981 JJ3, 1426-1435. or
40 CFR, Part 136, Appendix B.
2. "Carcinogens - Working With Carcinogens," Department of Health, Education,
and Welfare, Public Health Service, Center for Disease Control, National
Institute for Occupational Safety and Health, Publication No. 77-206,
August 1977.
3. "OSHA Safety and Health Standards, General Industry," (29 CFR 1910),
Occupational Safety and Health Administration, OSHA 2206 (Revised
January 1976).
4. "Safety in Academic Chemistry Laboratories," American Chemical Society
Publication, Committee on Chemical Safety, 3rd Edition, 1979.
5. Eichelberger, J.W., Munch J.W., and Shoemaker, J.A. "Determination of
Organic Compounds in Drinking Water by Liquid-Solid Extraction and
Capillary Column Gas Chromatography/Mass Spectrometry," U.S.
Environmental Protection Agency, Environmental Monitoring Systems
Laboratory, Cincinnati, Ohio.
508.1-17
-------
17.0 TABLES, DIAGRAMS, FLOWCHARTS, AND VALIDATION DATA
TABLE 1. RETENTION TIMES FOR METHOD ANALYTES USING THE GC
COLUMN IN SECTION 6.7 AND THE GC CONDITIONS IN SECTION 10.2
Analyte
Retention Time (minutes)
Hexachlorocyclopentadiene
9.64
Etridiazole
11.41
Chloroneb
12.39
Propachlor
14.69
Trifluralin
16.29
HCH-alpha
17.01
Hexachlorobenzene
17.44
Simazine
17.86
Atrazine
18.23
HCH-Beta
18.33
HCH-Gamma
18.71
HCH-Delta
19.21
Chlorthalonil
20.27
Metribuzin
21.88
Heptachlor
22.78
Alachlor
22.86
Aldrin
24.81
Metolachlor
25.02
Cyanazine
25.21
DCPA
26.49
Heptachlor Epoxide
27.20
Chlordane-Gamma
28.65
Endosulfan I
29.36
Chlordane-alpha
29.58
Dieldrin
30.95
4,4'-DDE
31.97
Endrin
32.24
Endosulfan II
32.81
Chlorbenzilate
32.98
4,4'-DDD
33.49
Endrin Aldehyde
33.96
Endosulfan sulfate
35.43
4,4'-DDT
35.80
Methoxychlor
39.38
cis-Permethrin
44.98
trans-Permethrin
45.42
Internal Standard (IS)
Pentachloronitrobenzene: 19.02 minutes
Surrogate (SUR)
4,4-Dibromobiphenyl: 25.64 minutes
508.1-18
-------
TABLE 2. LABORATORY PERFORMANCE CHECK SOLUTION
Test
Analyte
Cone,
Hg/mL
Requirements
Sensitivity
Chlorpyrifos
0.0020
Detection of analyte; S/N >3
Chromatographic performance
DCPA
0.0500
0.80 < PGF <1.15
Column performance
Chlorothalonil
0.0500
Resolution >0.50b
HCH-delta
0.0400
aPGF - peak Gaussian factor. Calculated using the equation:
PGF _ 1-83 x W (1/2)
W (1/10)
where: W(l/2) is the peak width at half height and W(l/10) is the peak width at tenth height.
bResolution between the two peaks as defined by the equation:
R = —
W
where: t is the difference in elution times between the two peaks and W is the average peak width, at the baseline, of
the two peaks.
-------
TABLE 3. MDL STATISTICAL RESULTS SEVEN REPLICATES IN REAGENT
WATER ANALYTE CONCENTRATIONS 0.01 |ig/L
Mean
Std. Dev.
Calc.
Analyte
(Pg/L)
% REC
(Pg/L)
% RSD
MDL
Alachlor
0.008
80
0.0030
37.5
0.009
Aldrin
0.008
80
0.0030
37.5
0.009
Atrazine
0.014
140
0.0010
7.14
0.003
Chlorbenzilate
0.008
80
0.0007
8.75
0.002
Chlordane-alpha
0.007
70
0.0012
17.1
0.004
Chlordane-gamma
0.006
60
0.003
50.0
0.001
Chloroneb
0.012
120
0.0019
15.8
0.006
Chlorothalonil
0.007
70
0.0007
10.0
0.002
Cyanazine
0.010
100
0.0022
22.0
0.007
DCPA
0.010
100
0.0028
28.0
0.009
4,4'-DDD
0.009
90
0.0008
8.89
0.003
4,4'-DDE
0.008
80
0.0009
11.2
0.003
4,4'-DDT
0.012
120
0.0011
9.17
0.004
4,4'-Dibromobiphenyl
0.440
88.0
0.027
6.14
(Surrogate)
Dieldrin
0.007
70
0.0009
12.9
0.003
Endosulfan I
0.007
70
0.0019
27.1
0.006
Endosulfan II
0.007
70
0.0003
42.9
0.001
Endosulfan Sulfate
0.007
70
0.0010
14.3
0.003
Endrin
0.015
150
0.0023
15.3
0.007
Endrin Aldehyde
0.008
80
0.0012
15.0
0.004
Etridiazole
0.011
110
0.0045
40.9
0.014
HCH-alpha
0.007
70
0.0003
42.8
0.001
HCH-beta
0.009
90
0.0029
32.2
0.009
HCH-delta
0.008
80
0.0014
17.5
0.004
HCH-gamma
0.007
70
0.0020
28.6
0.006
Heptachlor
0.009
90
0.0016
17.8
0.005
Heptachlor Epoxide
0.006
60
0.0003
5.0
0.001
Hexachlorobenzene
0.010
100
0.0004
4.0
0.001
Hexachlorocyclopentadiene
0.004
40
0.0013
32.5
0.004
Methoxychlor
0.006
60
0.0009
15.0
0.003
Metolochlor
0.013
130
0.0049
37.7
0.015
Metribuzin
0.009
90
0.0028
31.1
0.009
cis-Permethrin
0.007
70
0.0030
42.9
0.009
trans-Permethrin
0.011
110
0.0022
20.0
0.007
Propachlor
0.008
80
0.0027
33.8
0.008
Simazine
0.009
90
0.0025
27.8
0.008
Trifluralin
0.006
60
0.0003
5.0
0.001
508.1-20
-------
TABLE 4. EIGHT REPLICATES IN REAGENT WATER ANALYTE
CONCENTRATIONS 0.03 |ig/L
Mean
Std. Dev.
Analyte
(l-ig/L)
% REC
(l-ig/L)
% RSD
Alachlor
0.031
103
0.005
16.1
Aldrin
0.025
81.9
0.005
20.2
Atrazine
0.021
70.4
0.002
11.4
Chlorbenzilate
0.024
81.5
0.006
23.1
Chlordane-alpha
0.025
83.4
0.005
18.8
Chlordane-gamma
0.025
82.3
0.007
28.8
Chloroneb
0.026
88.3
0.006
24.3
Chlorothalonil
0.032
106
0.006
19.5
Cyanazine
0.029
95.2
0.004
12.8
DCPA
0.026
85.2
0.004
14.1
4,4'-DDD
0.027
89.1
0.004
16.4
4,4'-DDE
0.023
78.0
0.005
20.0
4,4'-DDT
0.028
93.8
0.005
17.4
4,4'-Dibromobiphenyl (Surrogate)
0.466
93.2
0.032
6.97
Dieldrin
0.027
91.5
0.004
15.8
Endosulfan I
0.028
92.6
0.005
17.8
Endosulfan II
0.026
87.9
0.005
18.6
Endosulfan Sulfate
0.032
106
0.004
11.5
Endrin
0.029
96.5
0.004
13.9
Endrin Aldehyde
0.030
98.8
0.004
13.7
Etridiazole
0.028
95.3
0.008
27.1
HCH-alpha
0.026
88.4
0.007
24.9
HCH-beta
0.028
95.0
0.004
13.9
HCH-delta
0.034
114
0.004
11.1
HCH-gamma
0.033
110
0.004
11.3
Heptachlor Epoxide
0.027
90.6
0.005
17.4
Heptachlor
0.026
85.6
0.006
22.1
Hexachlorobenzene
0.032
107
0.006
20
Hexachlorocyclopentadiene
0.015
50.8
0.007
44.8
Methoxychlor
0.024
92.7
0.003
10.7
Metolochlor
0.034
113
0.006
18.2
Metribuzin
0.012
39.5
0.002
15.8
cis-Permethrin
0.033
81.2
0.004
17.8
trans-Permethrin
0.033
111
0.004
13.4
Propachlor
0.028
93.0
0.005
17.4
Simazine
0.020
68.4
0.002
11.5
Trifluralin
0.024
80.5
0.004
18.0
508.1-21
-------
TABLE 5. EIGHT REPLICATES IN REAGENT WATER ANALYTE
CONCENTRATIONS 0.048 ng/L
Mean
Std. Dev.
Analyte
(l-ig/L)
% REC
(l-ig/L)
% RSD
Alachlor
0.044
91.1
0.002
3.70
Aldrin
0.034
69.8
0.004
11.5
Atrazine
0.036
74.9
0.002
6.60
Chlorbenzilate
0.051
107
0.004
8.40
Chlordane-alpha
0.047
97.7
0.002
4.80
Chlordane-gamma
0.044
92.6
0.003
5.40
Chloroneb
0.055
155
0.004
6.70
Chlorothalonil
0.059
123
0.004
6.00
Cyanazine
0.045
94.5
0.000
3.60
DCPA
0.042
88.5
0.001
2.90
4,4'-DDD
0.052
108
0.003
5.80
4,4'-DDE
0.046
94.8
0.004
8.30
4,4'-DDT
0.056
116
0.004
7.20
4,4'-Dibromobiphenyl (Surrogate)
0.474
94.7
0.032
6.79
Dieldrin
0.048
101
0.002
4.00
Endosulfan I
0.049
102
0.004
7.50
Endosulfan II
0.051
106
0.004
7.80
Endosulfan Sulfate
0.056
117
0.005
9.30
Endrin
0.053
111
0.004
8.20
Endrin Aldehyde
0.047
98.5
0.005
10.7
Etridiazole
0.051
107
0.003
6.46
HCH-alpha
0.052
109
0.005
10.0
HCH-beta
0.044
90.7
0.002
3.60
HCH-delta
0.058
120
0.005
8.80
HCH-gamma
0.053
111
0.007
13.3
Heptachlor
0.040
82.6
0.004
9.80
Heptachlor Epoxide
0.048
100
0.003
6.60
Hexachlorobenzene
0.044
90.7
0.005
11.8
Hexachlorocyclopentadiene
0.025
52.6
0.005
19.1
Methoxychlor
0.052
109
0.005
9.50
Metolochlor
0.060
126
0.002
3.60
Metribuzin
0.033
67.7
0.006
18.1
cis-Permethrin
0.049
102
0.009
18.9
trans-Permethrin
0.056
117
0.007
11.7
Propachlor
0.049
102
0.002
3.33
Simazine
0.039
82.2
0.003
6.69
Trifluralin
0.0043
89.9
0.002
4.71
508.1-22
-------
TABLE 6. EIGHT REPLICATES IN REAGENT WATER CONTAINING FULVIC
ACID (1 mg/L) ANALYTE CONCENTRATIONS 0.096 |ig/L
Mean
Std. Dev.
Analyte
(l-ig/L)
% REC
(l-ig/L)
% RSD
Alachlor
0.093
96.6
0.012
13.2
Aldrin
0.071
73.6
0.006
8.90
Atrazine
0.069
71.9
0.005
9.30
Chlorbenzilate
0.086
89.9
0.009
10.4
Chlordane-alpha
0.088
91.9
0.004
4.90
Chlordane-gamma
0.072
74.5
0.006
7.50
Chloroneb
0.082
85.4
0.008
9.70
Chlorothalonil
0.079
82.5
0.007
9.20
Cyanazine
0.085
89.0
0.011
12.5
DCPA
0.075
78.6
0.004
4.90
4,4'-DDD
0.091
95.0
0.009
10.3
4,4'-DDE
0.095
96.5
0.005
5.00
4,4'-DDT
0.082
85.0
0.008
9.50
4,4'-Dibromobiphenyl (Surrogate)
0.046
91.2
0.030
6.64
Dieldrin
0.089
92.3
0.009
9.90
Endosulfan I
0.088
91.8
0.008
8.60
Endosulfan II
0.088
92.0
0.006
7.40
Endosulfan Sulfate
0.094
98.3
0.007
7.30
Endrin
0.098
102
0.010
10.3
Endrin Aldehyde
0.067
69.8
0.003
5.20
Etridiazole
0.095
98.9
0.009
9.80
HCH-alpha
0.092
95.4
0.006
6.70
HCH-beta
0.088
91.2
0.007
7.80
HCH-delta
0.094
97.6
0.006
5.90
HCH-gamma
0.102
106
0.007
7.10
Heptachlor
0.068
71.4
0.007
9.80
Heptachlor Epoxide
0.088
91.6
0.007
7.80
Hexachlorobenzene
0.063
65.3
0.006
8.90
Hexachlorocyclopentadiene
0.021
21.7
0.008
40.1
Methoxychlor
0.092
96.1
0.011
12.0
Metolochlor
0.110
115
0.012
11.1
Metribuzin
0.039
40.7
0.004
9.50
cis-Permethrin
0.078
81.3
0.009
11.1
trans-Permethrin
0.082
85.2
0.008
11.1
Propachlor
0.098
102
0.017
17.4
Simazine
0.076
78.8
0.005
6.10
Trifluralin
0.074
77.4
0.010
13.3
508.1-23
-------
508.1-24
-------
Figure 1. Aroelor 1016. Chromatogram of LFB at 0.2 ug/L
TIME (MIN)
Figure 2. Aroelor 1221. Chromatogram of LFB at 0.2 ug/L
s
a
Ifl
. L
JUL
J
-i—¦—¦—i—i—i ¦ ¦ ¦ ¦ '
10
15
20 25 30
TIME (MIN)
35
40
508.1-25
-------
Figure 3. Aroclor 1232. Chromatogram of LFB at 0.2ug/L
Figure 4. Aroclor 1242. Chromatogram of LFB at 0.2ug/L
TIME (MIN)
508.1-26
-------
Figure 5. Aroclor 1248. Chroma tog ram of LFB at 0.2ug/L
|