5380 . __.
001D86101
DETERMINATION OF MERCAPTOBENZOTHIAZOLE IN WASTEWATERS
BY LIQUID CHROMATOGRAPHY
METHOD 640
7
Scope and Application
1.1 This method covers the determination of mercaptobenzothiazole.
The following parameter can be determined by this method:
Parameter CAS No.
Mercaptobenzothiazole 149-30-4
1.2 This is a high performance liquid chromatographic (HPLC)
method applicable to the determination of the compound listed
above in municipal and industrial discharges as provided
under 40 CFR 136.1. Any modification of this method beyond
those expressly permitted, shall be considered a major
modification subject to application and approval of
alternate test procedures under 40 CFR 136.4 and 136.5.
1.3 The method detection limit (MDL, defined in Section 14) for
each parameter is listed in Table 1. The MDL for a specific
U.S. Environmental Protection Agency
Region V, library
230 South Dearborn Street
Chic?*o, Illinois 60604
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U.S. Environmental Protection Agency
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wastewater may differ from those listed, depending upon the nature
of Interferences in the sample matrix.
1.4 The sample extraction and concentration steps in this method are
essentially the same as in certain other 600 series methods. Thus, a
single sample may be extracted to measure the compounds included in
the scope of the methods. When cleanup is required, the concen-
tration levels must be high enough to permit selecting aliquots, as
necessary, in order to apply appropriate cleanup procedures.
1.5 This method is restricted to use by or under the supervision of
analysts experienced in the use of liquid chromatoqraoh.y and in the
interpretation of liquid chromatograms. Each analyst must demonstrate
the ability to generate acceptable results with this method using
the procedure described in Section 8.2.
1.6 When this method is used to analyze unfamiliar samples for any or
all of the compounds above, compound identifications should be
supported by at least one additional qualitative technique. This
method describes analytical conditions for a second liquid
chromatographic column that can be used to confirm measurements
made with the primary column.
2. Summary of Method
2.1 A measured volume of sample, approximately 1 liter, is solvent ex-
tracted with methylene chloride using a separatory funnel. The
methylene chloride extract is dried and concentrated to 1.0 ml.
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Liquid chromatographic conditions are described which permit the
separation and measurement of the compounds in the extract by high
performance liquid chromatography with ultraviolet detection.
2.2 This method provides a silica gel column cleanup procedure to aid
in the elimination of interferences which may be encountered.
3. Interferences
3.1 Method interferences may be caused by contaminants in solvents,
reagents, glassware, and other sample processing apparatus that
lead to discrete artifacts or elevated baseline in liquid
chromatograms. All reagents and apparatus must be routinely
demonstrated to be free from interferences under the conditions of
the analysis by running laboratory reagent blanks as described in
Section 8.5.
3.1.1 Glassware must be scrupulously cleaned.2 Clean all
glassware as soon as possible after use by thoroughly
rinsing with the last solvent used 1n it. Follow by washing
with hot water and detergent and thorough rinsing with tap
and reagent water. Drain dry, and heat in an oven or muffle
furnace at 400°C for 15 to 30 min. Do not heat volumetric
ware. Some thermally stable materials such as PCBs may not
be eliminated by this treatment. Thorough rinsing with acetone
and pesticide quality hexane may be substituted for the
heating. After drying and cooling, seal and store glassware
in a clean environment to prevent any accumulation of dust
or other contaminants. Store inverted or capped with
aluminum foil.
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3.1.2 The use of high purity reagents and solvents helps to mini-
mize Interference problems. Purification of solvents by
distillation in all-glass systems may be required.
3.2 Matrix interferences may be caused by contaminants that are coex-
tracted from the sample. The extent of matrix interferences will
vary considerably from source to source, depending upon the nature
and diversity of the industrial complex or municipality sampled.
The cleanup procedure in Section 11 can be used to overcome many of
these interferences, but unique samples may require additional
cleanup approaches to achieve the MDL listed in Table 2.
4. Safety
4.1 The toxicity or carcinogenicity of each reagent used in this method
has not been precisely defined; however, each chemical compound
should be treated as a potential health hazard. From this
viewpoint, exposure to these chemicals must be reduced to the
lowest possible level by whatever means available. The laboratory
is responsible for maintaining a current awareness file of OSHA
regulations regarding the safe handling of the chemicals specified
in this method. A reference file of material data handling sheets
should also be made available to all personnel involved in the
chemical analysis. Additional references to laboratory safety are
available and have been identified3-5 for the information of the
analyst.
5. Apparatus and Materials
5.1 Sampling equipment, for discrete or composite sampling.
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5.1.1 Grab sample bottle - Amber boroslllcate or flint glass,
1-Hter or 1-quart volume, fitted with screw caps lined with
Teflon. Foil may be substituted for Teflon if the sample is
not corrosive. If amber bottles are not available, protect
samples from light. The container and cap liner must be
washed, rinsed with acetone or methylene chloride, and dried
before use to minimize contamination.
5.1.2 Automatic sampler (optional) - Must incorporate glass sample
containers for the collection of a minimum of 250 ml.
Sample containers must be kept refrigerated at 4°C and
protected from light during compositing. If the sampler
uses a peristaltic pump, a minimum length of compressible
silicone rubber tubing may be used. Before use, however,
the compressible tubing should be thoroughly rinsed with
methanol, followed by repeated rinsings with distilled water
to minimize the potential for contamination of the sample.
An integrating flow meter is required to collect flow
proportional composites.
5.2 Glassware (All specifications are suggested. Catalog numbers are
included for illustration only.)
5.2.1 Separatory funnel - 2000-mL, with Teflon stopcock.
5.2.2 Drying column - Chromatographic column 400 mm long x 10 mm
ID with coarse frit.
5.2.3 Chromatographic column • 400 mm long x 19 mm ID with 250 ml
reservoir at the top and Teflon stopcock (Kontes K-420290 or
equivalent).
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5.2.4 Concentrator tube, Kuderna-Danish - 10-mL, graduated (Kontes
K-570050-1025 or equivalent). Calibration must be checked
at the volumes employed In the test. A ground glass stopper
1s used to prevent evaporation of extracts.
5.2.5 Evaporative flask, Kuderna-Danish - 500-mL (Kontes
K-570001-0500 or equivalent). Attach to concentrator tube
with springs.
5.2.6 Snyder column, Kuderna-Danish - three-ball macro/Kontes
K-503000-0121 or equivalent).
5.2.7 Snyder column, Kuderna-Danish - two-ball micro (Kontes
K-569001-0219 or equivalent).
5.2.8 Vials - Amber glass, 10 to 15 ml capacity with Teflon lined
screw-cap.
5.2.9 Erlenmeyer flask - 250-mL
5.2.10 Graduated cylinder - 1000-mL
5.2.11 Volumetric flask - 5-mL, 10-mL
5.3 Boiling chips - approximately 10/40 mesh carborundum. Heat at
400°C for 4 hours or Soxhlet extract with methylene chloride
5.4 Water bath - Heated, capable of temperature control (±2°C). The
bath should be used in a hood.
5.5 Balance - Analytical, capable of accurately weighing to the nearest
0.0001 g.
5.6 Liquid chromatograph - Analytical system complete with liquid
chromatograph suitable for on-column injection and all required
accessories including syringes, analytical columns, detectors,
and strip-chart recorder. A data system is recommended for
measuring peak areas.
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5.6.1 Column 1 - Spherisorb-ODS, 5 micron, 250 mm long x 4.6 mm
ID or equivalent. This column was used to develop the method
performance statements in Section 14. Alternate columns may
be used in accordance with the provisions described in
Section 12.1.
5.6.2 Column 2 - Lichrosorb RP-2, 5 micron, 250 mm long x 4.6 mm
ID or equivalent.
6- Reagents
6.1 Reagent water - Reagent water is defined as a water in which an
interferent is not observed at the method detection limit of each
parameter of interest.
6.2 Methylene chloride, methanol, acetonitrile, ethyl ether, and
acetone distilled-in-glass quality or equivalent. Ethyl ether must
be free of peroxides as indicated by EM Quant Test Strips (available
from Scientific Products Co., Catalog No. P1126-8 and other
suppliers). Procedures recommended for removal of peroxides are
provided with the test strips.
6.3 Sodium sulfate (ACS) Granular, anhydrous; heated in a muffle
furnace at 400°C overnight.
6.4 Silica gel, Davison Grade 923, 100-200 mesh, dried for 12 hours
at 150eC.
6.5 IN. Sodium hydroxide. Dissolve 4.0 grams of sodium hydroxide
in 100 ml of distilled water.
6.6 IN^Sulfuric acid. Slowly add 2.8 ml of cone. H2S04 (94%)
to about 50 ml of distilled water. Dilute to 100 ml with
distilled water.
6.7 Sodium phosphate, monobasic, ACS grade.
6.8 Sodium phosphate, dibasic, ACS grade.
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6.9 Stock standard solutions (1.00 ug/uL) - Stock standard solutions
can be prepared from pure standard materials or purchased as
certified solutions.
6.9.1 Prepare stock standard solutions by accurately weighing about •
0.0100 grams of pure material. Dissolve the material 1n
distilled-1n-glass quality methanol and dilute to volume in
a 10-mL volumetric flask. Larger volumes can be used at the
convenience of the analyst. If compound purity 1s certified
at 96% or greater, the weight can be used without correction
to calculate the concentration of the stock standard.
Commercially prepared stock standards can be used at any
concentration if they are certified by the manufacturer or by
an independent, source.
6.9.2 Transfer the stock standard solutions into Teflon-sealed
screw-cap bottles. Store at 4°C and protect from light.
Frequently check standard solutions for signs of degradation
or evaporation, especially just prior to preparing
calibration standards from them.
6.9.3 Stock standard solutions must be replaced after six months
or sooner if comparison with check standards indicates a
problem.
7. Calibration
7.1 Establish liquid chromatographic operating parameters equivalent to
those indicated in Table 1. The liquid chromatographic system can be
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calibrated using the external standard technique (Section 7.2} or
the internal standard technique (Section 7.3).
7.2 External standard calibration procedure:
7.2.1 For each compound of interest, prepare calibration standards
at a minimum of three concentration levels by adding volumes
of one or more stock standards to a volumetric flask and
diluting to volume with methanol. One of the external
standards should be at a concentration near, but above, the
method detection limit. The other concentrations should
correspond to the range of concentrations expected in the
sample concentrates or should define the working range of
the detector.
7.2.2 Using injection of 5 to 20 yL of each calibration standard,
tabulate peak height or area responses against the mass
injected. The results can be used to prepare a calibration
curve for each compound. Alternatively, the ratio of the
response to the mass injected, defined as the calibration
factor (CF), can be calculated for each compound at each
standard concentration. If the relative standard deviation
of the calibration factor is less than 10% over the working
range, the average calibration factor can be used in
place of a calibration curve.
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7.2.3 The working calibration curve or calibration factor must be
verified on each working shift by the measurement of one or
more calibration standards. If the response for any
compound varies from the predicted response by more than
_+10%, the test must be repeated using a fresh calibration
standard. Alternatively, a new calibration curve or
calibration factor must be prepared for that compound.
7.3 Internal standard calibration procedure. To use this approach, the
analyst must select one or more Internal standards similar in
analytical behavior to the compounds of Interest. The analyst must
further demonstrate that the measurement of the internal standard
1s not affected by method or matrix Interferences. Due to these
limitations, no Internal standard applicable to all samples can be
suggested.
7.3.1 Prepare calibration standards at a minimum of three
concentration levels for each compound of interest by adding
volumes of one or more stock standards to a volumetric
flask. To each calibration standard, add a known constant
amount of one or more internal standards, and dilute to
volume with methanol. One of the standards should be at
a concentration near, but above, the method detection limit.
The other concentrations should correspond to the range of
concentrations expected in the sample concentrates or should
define the working range of the detector.
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7.3.2 Using Injections of 5 to 20 wL of each calibration standard,
tabulate the peak height or area responses against the
concentration for each compound and internal standard.
Calculate response factors (RF) for each compound as
follows:
where:
AS * Response for the compound to be measured.
AjS - Response for the internal standard.
Cfs " Concentration of the internal standard in yg/L.
GS * Concentration of. the compound to be measured in
If the RF value over the working range is constant, less
than 10% relative standard deviation, the RF can be assumed
to be invariant and the average RF can be used for
calculations. Alternatively, the results can be used to
plot a calibration curve of response ratios, AS/A-JS
against RF.
7.3.3 The working calibration curve or RF must be verified on each
working shift by the measurement of one or more calibration
standards. If the response for any compound varies from the
predicted response by more than +10%, the test must be
repeated using a fresh calibration standard. Alternatively,
a new calibration curve must be prepared for that compound.
7.4 Before using any cleanup procedure, the analyst must process a
series of calibration standards through the procedure to validate
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elution patterns and the absence of Interferences from the
reagents.
8. Quality Control
8.1 Each laboratory using this method 1s required to operate a formal
quality control program. The minimum requirements of this program
consist of an Initial demonstration of laboratory capability and
the analysis of spiked samples as a continuing check on
performance. The laboratory Is required to maintain performance
records to define the quality of data that Is generated.
8.1.1 Before performing any analyses, the analyst must demonstrate
the ability to generate acceptable accuracy and precision
with this method. This ability 1s established as described
1n Section 8.2.
8.1.2 In recognition of the rapid advances occurring In chromato-
graphy, the analyst 1s permitted certain options to Improve
the separations or lower the cost of measurements. Each
time such modifications to the method are made, the analyst
Is required to repeat the procedure 1n Section 8.2.
8.1.3 The laboratory must spike and analyze a minimum of 10% of
all samples to monitor continuing laboratory performance.
This procedure 1s described 1n Section 8.4.
8.2 To establish the ability to generate acceptable accuracy and
precision, the analyst must perform the following operations.
8.2.1 Select a representative spike concentration for each
compound to be measured. Using stock standards, prepare a
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quality control check sample concentrate In methanol 1000
times more concentrated than the selected concentrations.
8.2.2 Using a pi pet, add 1.00 ml of the check sample concentrate
to each of a minimum of four 1000-mL aliquots of reagent
water. A representative wastewater may be used in place of
the reagent water, but one or more additional aliquots must
be analyzed to determine background levels, and the spike
level must exceed twice the background level for the test to
be valid. Analyze the aliquots according to the method
beginning in Section 10.
8.2.3 Calculate the average percent recovery (R), and the standard
deviation of the percent recovery (s), for the results.
Uastewater background corrections must be made before R and
s calculations are performed.
8.2.4 Using the appropriate data from Table 2, determine the
recovery and single operator precision expected for the
method, and compare these results to the values measured in
Section 8.2.3. If the data are not comparable, the analyst
must review potential problem areas and repeat the test. .
8.3 The analyst must calculate method performance criteria and define
the performance of the laboratory for each spike concentration and
parameter being measured.
8.3.1 Calculate upper and lower control limits for method
performance as follows:
Upper Control Limit (UCL) » R + 3 s
Lower Control Limit (LCL) - R - 3 s
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where R and s are calculated as In Section 8.2.3. The UCL
and LCL can be used to construct control charts6 that are
useful in observing trends in performance.
8.3.2 The laboratory must develop and maintain separate accuracy
statements of laboratory performance for wastewater samples.
An accuracy statement for the method 1s defined as R ^ s.
The accuracy statement should be developed by the analysis
of four aliquots of wastewater as described in Section
8.2.2, followed by the calculation of R and s. Alternately,
the analyst may use four wastewater data points gathered
through the requirement for continuing quality control in
Section 8.4. 'The accuracy statements should be updated
regularly.6
8.4 The laboratory 1s required to collect in duplicate a portion of
their samples to monitor spike recoveries. The frequency of spiked
sample analysis must be at least 10% of all samples or one sample
per month, whichever 1s greater. One aliquot of the sample must be
spiked and analyzed as described in Section 8.2. If the recovery
for a particular compound does not fall within the control limits
for method performance, the results reported for that compound in
all samples processed as part of the same set must be qualified as
described in Section 13.3. The laboratory should monitor the
frequency of data so qualified to ensure that 1t remains at or
below 5%.
8.5 Before processing any samples, the analyst should demonstrate
though the analysis of a 1-liter aliquot of reagent water that all
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glassware and reagents Interferences are under control. Each time
a set of samples 1s extracted or there Is a change In reagents, a
laboratory reagent blank should be processed as a safeguard against
laboratory contamination.
8.6 It 1s recommended that the laboratory adopt additional quality
assurance practices for use with this method. The specific
practices that are most productive depend upon the needs of the
laboratory and the nature of the samples. Field duplicates may be
analyzed to monitor the precision of the sampling technique. When
doubt exists over the Identification of a peak on the chromatogram,
confirmatory techniques such as gas chromatography with a
dissimilar column, specific element detector, or mass spectrometer
must be used. Whenever possible, the laboratory should perform
analysis of standard reference materials and participate in
relevant performance evaluation studies.
9. Samples Collection, Preservation, and Handling
9.1 Grab samples must be collected in glass containers. Conventional
sampling practices7 should be followed; however, the bottle must
not be prerinsed with sample before collection. Composite samples
should be collected in refrigerated glass containers in accordance
with the requirements of the program. Automatic sampling equipment
must be as free as possible of plastic and other potential sources
of contamination.
*
9.2 The samples must be Iced or refrigerated at 4°C from the time of
collection until extraction.
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9.3 Adjust the pH of the sample to 6 to 8 with sodium hydroxide or
sulfuric acid immediately after sampling.
10. Sample Extraction
10.1 Mark the water meniscus on the side of the sample bottle for later
determination of sample volume. Pour the entire sample into a
2-liter separatory funnel. Check the pH of the sample with wide
range pH paper and adjust to 6 to 8 with 1 N sodium hydroxide or
1 N sulfuric acid. Dissolve 5 grams of monobasic sodium phosphate
and 5 grams of dibasic sodium phosphate in the sample.
10.2 Add 60 ml of methylene chloride to the sample bottle, seal, and
shake 30 seconds to rinse the inner walls. Transfer the solvent to
the separatory funnel and extract the sample by shaking the funnel
for 2 min with periodic venting to release excess pressure. Allow
the organic layer to separate from the water phase for a minimum of
10 min. If the emulsion interface between layers is more than one
third the volume of the solvent layer, the analyst must employ
mechanical techniques to complete the phase separation. The
optimum technique depends upon the sample, but may include
stirring, filtration of the emulsion through glass wool, centrifu-
gation, or other physical methods. Collect the methylene chloride
extract in a 250-mL Erlenmeyer flask.
10.3 Add a second 60-ml volume of methyl ene chloride to the sample
bottle and repeat the extraction procedure a second time, combining
the extracts in the Erlenmeyer flask. Perform a third extraction
in the same manner.
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10.4 Assemble a Kuderna-Danish (K-D) concentrator by attaching a 25-mL
concentrator tube to a 500-ml evaporative flask. Other concentra-
tion devices or techniques may be used in place of the K-D if the
requirements of Section 8.2 are met.
10.5 Pour the combined extract through a drying column containing about
10 cm of anhydrous sodium sulfate, and collect the extract in the
K-D concentrator. Rinse the Erlenmeyer flask and column with 20 to
30 ml of methylene chloride to complete the quantitative transfer.
Once the flask rinse has passed through the drying column, rinse
the column with 30 to 40 ml of methyl ene chloride.
10.6 Add 1 or 2 clean boiling chips to the evaporative flask and attach
a three-ball Snyder column. Prewet the Snyder column by adding
about 1 ml methylene chloride to the top. Place the K-D apparatus
on a hot water bath, 60 to 65°C, so that the concentrator tube 1s
partially Immersed in the hot water, and the entire lower rounded
surface of the flask 1s bathed with hot vapor. Adjust the vertical
position of the apparatus and the water temperature as required to
complete the concentration in 15 to 20 min. At the proper rate of
distillation, the balls of the column will actively chatter but the
chambers will not flood with condensed solvent. When the apparent
.volume of liquid reaches 1 ml, remove the K-D apparatus and allow
it to drain and cool for at least 10 min.
10.7 Remove the macro-Snyder column and rinse the flask and Its lower
joint into the concentrator tube with 1 to 2 ml of methyl ene
chloride. Add 1 or 2 clean boiling chips and attach a two-ball
micro-Snyder column to the concentrator tube. Prewet the
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micro-Snyder column with methylene chloride and concentrate the
solvent extract as before. When an apparent volume of 0.5 ml is
reached, or the solution stops boiling, remove the K-D apparatus
and allow it to drain and cool for 10 minutes.
10.8 Remove the micro-Snyder column and adjust the volume of the extract
to 1.0 ml with methylene chloride. Stopper the concentrator tube
and store refrigerated if further processing will not be performed
immediately. If the extract is to be stored longer than two days,
transfer the extract to a screw capped vial with a Teflon-lined
cap. If the sample extract requires no further cleanup, proceed
with Section 10.9. If the sample requires cleanup, proceed to
Section 11.
10.9 Add 1 or 2 clean boiling chips to the concentrator tube along
with 10-ml of methanol. Attach a two-ball micro-Snyder column and
prewet the micro-Snyder column with about 1 ml of methanol. Concentrate
the solvent extract as before to an apparent volume of 2 ml
and allow it to drain and cool for 10 minutes. Transfer the solvent
extract to a 5 ml volumetric flask and dilute to the mark with methanol.
Proceed with the liquid chromatographic analysis in Section 12.
10.10 Determine the original sample volume by refilling the sample bottle
to the mark and transferring the water to a 1000-mL graduated
cylinder. Record the sample volume to the nearest 5 ml.
11. Cleanup and Separation
11.1 Cleanup procedures may not be necessary for a relatively clean
sample matrix. The cleanup procedure recommended in this method
has been used for the analysis of various clean waters and
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industrial effluents. If particular circumstances demand the use
of an alternative cleanup procedure, the analyst must determine the
elution profile and demonstrate that the recovery of each compound
of interest is not less than 85%.
11.2 The following silica gel column cleanup procedure has been demon-
strated to be applicable to mercaptobenzothiazole.
11.2.1 Add 10 g of silica gel to 100 ml of ethyl ether and 600 uL of
reagent water in a 250-mL Erlenmeyer flask. Shake vigorously
for 15 minutes. Transfer the slurry to a chromatographic
column (silica gel may be retained with a plug of glass wool).
Allow the solvent to elute from the column until the silica gel
is almost exposed to the air. Wash the column with 100 ml of
methylene chloride. Use a column flow of 2 to 2.5 mL/min
throughout the wash and elution profiles.
11.2.2 Quantitatively add the sample extract from Section 10.8 to
the head of the column. Allow thesolvent to elute from-the
column until the silica gel is almost exposed to the air.
Elute the column with 50 ml of methylene chloride. Discard
this fraction.
11.2.3 Elute the column with 50 ml of 6% acetone in methylene chloride
and collect eluate in a K-D apparatus. Concentrate this
fraction to 1 nt as described in Sections 10.6 and 10.7.
Exchange solvent with methanol as described in Section 10.9
and proceed with liquid chromatographic analysis.
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12. Liquid Chromatography
12.1 Table 1 summarizes the recommended operating conditions for the
liquid chromatograph. Included in this table are estimated retention
times and method detection limits that can be achieved by this
method. Examples of the separations achieved by Column 1 and
Column 2 are shown in Figures 1 and 2. Other columns, chromatographic
conditions, or detectors may be used if the requirements of Section
8.2 are met.
12.2 Calibrate the liquid chromatographic system daily as described in
Section 7.
12.3 If the internal standard approach is being used, the analyst must
not add the internal standard to the sample extracts until immediately
before injection into the instrument. Mix thoroughly.
12.4 Inject 5 to 20 yL of the sample extract. Record the
resulting peak sizes in area or peak height units.
12.5 The width of the retention time window used to make identifications
should be based upon measurements of actual retention time
variations of standards over the course of a day. Three times the
standard deviation of a retention time for a compound can be used
to calculate a suggested window size; however, the experience of
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the analyst should weigh heavily In the Interpretation of
chromatograms.
12.6 If the response for the peak exceeds the working range of the
system, dilute the extract and reanalyze.
12.7 If the measurement of the peak response Is prevented by the
presence of Interferences, further cleanup 1s required.
13. Calculations
13.1 Determine the concentration of Individual compounds in the sample.
13.1.1 If the external standard calibration procedure is used,
calculate the amount of material injected from the peak
response using the calibration curve or calibration factor
in Section 7.2.2. The concentration in the sample can be
calculated as follows:
(A)(Vt)
Concentration, yg/L
(Vi)(Vs)
where:
A • Amount of material injected, in nanograms.
V-j « Volume of extract Injected in uL.
Vt " Volume of total extract in uL.
Vs * Volume of water extracted in ml.
13.1.2 If the internal standard calibration procedure was used,
calculate the concentration in the sample using the response
factor (RF) determined in Section 7.3.2 as follows:
(As)(Is)
Concentration, ug/L
(Ais)(RF)(V0)
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where:
As * Response for the compound to be measured.
AJS « Response for the Internal standard.
Is » Amount of Internal standard added to each
extract 1n yg.
V0 - Volume of water extracted, 1n liters.
13.2 Report results 1n mlcrograms per liter without correction for
recovery data. When duplicate and spiked samples are analyzed,
report all data obtained with the sample results.
13.3 For samples processed as part of a set where the laboratory spiked
sample recovery falls outside of the control limits in Section 8.3,
data for the affected compounds must be labeled as suspect.
14. Method Performance
14.1 The method detection limit (HDL) is defined as the minimum concen-
tration of a substance that can be measured and reported with 99%
confidence that the value is above zero.11 The MDL concentrations
listed in Table 1 were obtained using reagent water.1 Similar
results were achieved using representative wastewaters.
14.2 This method has been tested for linearity of recovery from spiked
reagent water and has been demonstrated to be applicable over the
concentration range from 5 to 1000 ug/L.
14.3 In a single laboratory, Battelle Columbus Laboratories, using
spiked wastewater samples, the average recoveries presented in
Table 2 were obtained after silica gel cleanup. Seven replicates of
each of two different wastewaters were spiked and analyzed. The
standard deviation of the percent recovery is also included in
Table 2.1
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REFERENCES
1. "Development of Methods for Pesticides 1n Wastewaters," Report for EPA
Contract 68-03-2956 (In preparation).
2. ASTM Annual Book of Standards, Part 31, D3694, "Standard Practice for
Preparation of Sample Containers and for Preservation," American
Society for Testing and Materials, Philadelphia, PA, p. 679, 1980.
3. "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.
4. "OSHA Safety and Health Standards, General Industry," (29 CFR 1910),
Occupational Safety and Health Administration, OSHA 2206 (Revised,
January 1976).
5. "Safety In Academic Chemistry Laboratories," American Chemical Society
Publication, Committee on Chemical Safety, 3rd Edition, 1979.
6. "Handbook for Analytical Quality Control in Water and Wastewater
Laboratories," EPA-600/4-79-019, U. S. Environmental Protection Agency,
Environmental Monitoring and Support Laboratory - Cincinnati, Ohio
45268, March 1979.
7. ASTM Annual Book of Standards, Part 31, D3370, "Standard Practice for
Sampling Water," American Society for Testing and Materials,
Philadelphia, PA, p. 76, 1980.
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TABLE 1. CHROMATOGRAPHIC CONDITIONS AND METHOD DETECTION
LIMITS
Retention Time (Min) MDL
Parameter Column 1 Column 2 (ug/L)
Mercaptobenzothiazole 8.4 9.5 1.7
Column 1 conditions: Spherisorb-ODS, 5 micron, 250 x 4.6 mm;
1 mL/min flow; 50/50 acetonitrile/water.
Column 2 conditions: Lichrosorb RP-2, 5 micron, 250 x 4.6 mm;
1 mL/min flow; 10/90 acetonitrile/water.
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