oEPA
United States
Environmental Protection
Agency
Office of Watet
Engineering and Analysis Division (WH-552)
Washington, DC 20460
EPA821-R-92-008
December 1992
Methods for the Determination of
Diesel, Mineral, and Crude Oils in
Offshore Oil and Gas Industry
Discharges
Printed on Recycled Paper
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Acknowledgements
The methods in this compendium were prepared under the direction of William A. Telliard of the
U.S. Environmental Protection Agency's (EPA's) Office of Water (OW), Engineering and Analysis
Division (EAD). This document was prepared under EPA Contract No. 68-C9-0019 by the
Environmental Services Division of Viar & Company, a wholly-owned subsidiary of DynCorp. The
methods were written by Interface, Inc. The American Petroleum Institute and its member companies
supported much of the methods development.
Disclaimer
The methods in this compendium have been reviewed and approved for publication by the
Engineering and Analysis Division of the U.S. Environmental Protection Agency. Mention of trade
names or commercial products does not constitute endorsement or recommendation for use.
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Introduction
The U.S. Environmental Protection Agency (EPA) is promulgating effluent limitations guidelines
for the Offshore subcategory of the Oil and Gas Extraction Point-Source category at Subpart A of 40 CFR
Part 435, under the authority of the Clean Water Act. The rule will in part prohibit diesel oil in drilling
fluids (muds) and drill cuttings from being discharged from offshore oil and gas platforms. This
compendium of analytical methods supports the final rule. The methods are being promulgated under
the authority of Sections 304(h), 501 (a), and 308 of the Federal Water Pollution Control Act (FWPCA,
33 U.S.C. 1251, et. seq.). These sections require EPA to promulgate guidelines establishing test
procedures for the determination of pollutants in discharges and to require data collection whenever
necessary to carry out the objectives of the CWA. The test procedures were developed by EPA's
Engineering and Analysis Division within the Office of Water's Office of Science and Technology.
Method 1651 was proposed as part of the 40 CFR Part 435 rule (56 FR 10664-10715). In Method
1651, oil is removed from a mud sample using a thermal extraction apparatus called a "retort." The
solution from the retort is placed in a separatory funnel and extracted using methylene chloride. The
extract is evaporated to dryness in a Kuderna-Danish concentrator, and the weight of oil is determined
using an analytical balance. The oil is then redissolved in methylene chloride, an internal standard is
added, and an aliquot is analyzed by gas chromatography (GC). Diesel oil is identified by comparing
the pattern of GC peaks with the pattern produced by reference diesel oil.
The American Petroleum Institute (API) and its member companies criticized Method 1651,
arguing that it was unable to reliably distinguish diesel oil from mineral oil and certain permitted mud
additives and that the retort apparatus used in Method 1651 could not be operated reproducibly. In
response to this criticism, EPA worked with API to develop Methods 1662, 1654A, and 1663. A flow
chart of how these methods are employed is shown in Figure 1. In the final rule, Methods 1662, 1654A,
and 1663 are being allowed as variants of Method 1651.
Method 1662 is a laboratory extraction procedure employing a Soxhlet/Dean-Stark (SDS) extractor
for reliable removal of oil from the mud. A total oil measurement by gravimetry (weighing) can be made
with this procedure, if desired.
Methods 1654A and 1663 both use a portion of the extract from Method 1662. A portion of the
extract from Method 1651 can be used if desired, but the SDS extraction procedure in Method 1662
provides improved precision and accuracy over the retort procedure in Method 1651.
Method 1654A measures the polynuclear aromatic hydrocarbon (PAH) content of the oil as
phenanthrene by high-performance liquid chromatography with an ultra-violet detector (HPLC/UV). If
the PAH content of the oil is less than 0.35 weight percent, the oil is mineral oil. If the PAH content
is equal to or greater than 0.35 weight percent, the oil is diesel oil or crude oil.
Methods 1651 and 1663 both measure the presence and distribution of hydrocarbons in the oil by
gas chromatography with a flame ionization detector (GC/FID). Method 1651 uses pattern matching to
attempt to distinguish diesel oil from mineral or crude oil; Method 1663 uses the distribution of normal
aliphatic hydrocarbons (n-alkanes) in the Cg-Cjo range to distinguish diesel oil from crude oil.
Using Method 1663, the presence of n-alkanes in the Cg-C^ range indicates the presence of diesel
oil or crude oil. If less than 10 n-alkanes are present in the Cg-C^ range (at a signal-to-noise ratio
of 3 or greater for each n-alkane), diesel oil is not present. If 10 or more n-alkanes are present in the
C9-C24 range, the percentage of n-alkanes in the C^-Cy, range are used to determine if the oil is crude
oil. The oil is crude oil if the C^-C-x, n-alkane content is greater than 1.2 percent of the total Cg-Cy,
n-alkane content.
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Introduction
Methods 1651, 1654A, 1662, and 1663 all employ standardized 304(h) quality control. This QC
requires instrument calibration and periodic verification, initial and ongoing demonstration of laboratory
capability, and recovery of spikes in samples to demonstrate that the method is applicable to each sample
type tested.
Questions about the methods or this document should be addressed to:
William A. Telliard, Director
Analytical Methods Staff
Engineering and Analysis Division (WH-552)
U.S. Environmental Protection Agency
401 M Street, S.W.
Washington, DC 20460
(202) 260-7531
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Introduction
Method 1662
SDS extraction
Rotovap to approx imately 1 ml
Adjust volume to 5.0 ml with acetonitrile
Evaporate 4.0 ml to dryness with nitrogen blowdown
Determine total oil in 4.0-mL portion by gravimetry
Method 1654 A
Determine PAH content of 1.0-mL portion by HPLC/UV
if PAH content <0.35 wt %, oi! is mineral oil
If PAH content >0.35 wt %, oil may be diesel or crude oil
Method 1663
Determine n-alkane pattern of 1.0-mL portion by GC/FID
If <10 n-alkanes present in Cg-C24 range @ S/N >3, no diesei
If n-alkanes present in 09-630 range & ^25^30 n-a!kanes >1.2
% of total Cg-C3o n-alkanes, oil is crude oil
CS2-10-S
Figure 1. Differentiation of Diesel, Mineral, and Crude Oils by SDS Extraction,
HPLC/UV, and GC/FID, using Methods 1662, 1 654A, and 1663, respectively
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Contents
Introduction iii
Method 1651, Rev. A
Total Oil and Diesel Oil in Drilling Muds and Drill Cuttings
by Retort, Gravimetry, and GC/FID 1
Method 1654, Rev. A
PAH Content of Oil by HPLC/UV 23
Method 1662
Total Extractable Material in Drilling Mud by SDS Extraction and Gravimetry ... 39
Method 1663
Differentiation of Diesel and Crude Oil by GC/FID 55
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Method 1651, Revision A
Total Oil and Diesel Oil in
Drilling Muds and Drill Cuttings
by Retort,
Gravimetry, and GC/FID
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1651, Revision A
Total Oil and Diesel Oil in Drilling Muds and Drill Cuttings
by Retort, Gravimetry, and GC/FID
1. SCOPE AND APPLICA TION
1.1 This method is used to determine the total oil content and the identity and concentration of
diesel oil in drilling mud samples. It is applicable to all mud types and may also be used to
determine the total oil and diesel oil content of drill cuttings.
1.2 This method may be used for compliance monitoring purposes as part of the "Effluent
Limitations Guidelines and New Source Performance Standards for the Offshore Subcategory
of the Oil and Gas Extraction Point Source Category" [50 FR 34592].
1.3 When this method is used to analyze samples for which there is no reference diesel oil, diesel
oil identification shall be supported by at least one additional qualitative technique.
Method 1625 provides gas chromatograph/mass spectrometer (GC/MS) conditions appropriate
for the qualitative and quantitative confirmation of the presence of the components of diesel oil
(References 1 and 2).
1.4 The detection limit of this method is usually dependent upon the presence of other oils in the
sample. Excluding interferences, estimated detection limits of 200 mg/kg of total oil and
100 mg/kg of diesel oil can be obtained.
1.5 Any modification of this method beyond those expressly permitted shall be considered as a
major modification subject to application and approval of alternative test procedures under
40 CFR 136.4 and 136.5.
1.6 The gas chromatography portions of this method are restricted to use by or under the
supervision of analysts experienced in the use of gas chromatography and in the interpretation
of gas chromatograms. Each laboratory that uses this method must generate acceptable results
using the procedures described in Sections 8.2 and 12 of this method.
2. SUMMARY OF METHOD
2.1 A weighed amount of drilling mud is distilled using a retort apparatus. The distillate is
extracted with methylene chloride and the extract is dried by passage through sodium sulfate.
The extract is evaporated to dryness, and the total amount of oil in the sample is determined
gravimetrically. The oil, together with a measured volume of internal standard, is redissolved
in a known volume of methylene chloride, and an aliquot is injected into a gas chromatograph
(GC). The components of the oil are separated by the GC and detected using a flame
ionization detector (FID).
2.2 Identification of diesel oil (qualitative analysis) is performed by comparing the pattern of GC
peaks (retention times and intensities) from the sample extract with the pattern of GC peaks
from a reference diesel oil sample. Identification of diesel oil is established when the
reference diesel and sample patterns agree per the criteria in this method.
2.3 Quantitative analysis of diesel oil is performed using an internal standard technique.
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Method 1651A
3. CONTAMINATION AND INTERFERENCES
3.1 Solvents, reagents, glassware, and other sample processing hardware may yield artifacts and/or
elevated baselines causing misinterpretation of chromatograms.
3.1.1 All materials shall be demonstrated to be free from interferences under the conditions
of the analysis by running method blanks initially and with a set of samples. Specific
selection of reagents and purification of solvents by distillation in all-glass systems
may be required.
3.1.2 Glassware and, where possible, reagents are cleaned by solvent rinse or baking at
450°C for a minimum of 1 hour.
3.2 There is no standard diesel oil. Oil components, as seen by GC/FID, will differ depending
upon the oil source, the production date, production process, and the producer. In addition,
there are three basic types of diesel oils: ASTM Designations No. 1-D, No. 2-D, and
No. 4-D. The No. 2-D is the most common diesel oil; however, No. 2-D is sometimes
blended with No. 1-D, which has a lower boiling range. For rigorous identification and
quantification of diesel oil in a drilling fluid sample by GC/FID, the chromatographic pattern
from the diesel oil should be matched with the chromatographic pattern from a reference
standard of the same diesel oil suspected to be in the sample.
3.3 To aid in the identification of interferences, the chromatographic pattern from a reference
sample of drilling fluid prior to use is compared to the chromatographic pattern of the drilling
fluid after use. An interference is present when the pattern of the background oil does not
match, but contributes substantially to, the pattern of the diesel oil in the sample.
3.4 Mineral oils are often added to drilling fluids for lubricity. These oils, when examined by
GC/FID, contain some components common to diesel oil but have chromatographic patterns
that are distinctly different from diesel oil. The analyst must first determine if the sample
chromatogram shows the presence of diesel, mineral, or a combination of both before reliable
quantification can be performed. This method permits selection of GC peaks unique to diesel
oil for determination of diesel oil in the presence of mineral oil.
4. SAFETY
4.1 The toxicity or carcinogenicity of each reagent used in this method has not been defined.
Therefore, 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.
4.2 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 handling data sheets (MSDSs) should also be made available to all personnel involved
in the chemical analysis. Additional references to laboratory safety are available and have
been identified (References 3 through 5) for the information of the analyst.
4.3 Methylene chloride has been classified as a known health hazard. All steps in this method
which involve exposure to this compound shall be performed in an OSHA-approved fume
hood.
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Method 1651A
5. APPARA TUS AND MA TER/ALS
NOTE: Brand names, suppliers, and pan numbers are for illustrative purposes only.
No endorsement is implied. Equivalent performance may be achieved using apparatus
and materials other than those specified here, but demonstration of equivalent
performance meeting the requirements of this method is the responsibility of the
laboratory.
5.1 Sample bottles for discrete sampling.
5.1.1 Bottle: 4-oz Boston round wide-mouth jar with PTFE-lined screw-cap (Sargent Welsh
S-9184-72CA, or equivalent). New bottles are used as received with no further
cleaning required.
5.1.2 Bottle mailer: To fit bottles above (Sargent-Welsh 2306, or equivalent).
5.2 Distillation apparatus.
5.2.1 Retort: 20-mL retort apparatus (IMCO Services Model No. R2100 or equivalent).
5.2.2 Glass wool: Pyrex (Corning 3950, or equivalent). Solvent-extracted or baked at
450°C for a minimum of 1 hour.
5.3 Extraction/drying apparatus.
5.3.1 Separatory funnel: 60-mL with PTFE stopcock.
5.3.2 Drying column: Pyrex chromatographic column, 400 mm long by 15 to 20 mm i.d.,
equipped with coarse-glass frit or glass-wool plug.
5.3.3 Glass filtering funnel: Crucible holder (Corning No. 9480, or equivalent).
5.3.4 Spatulas: Stainless steel or PTFE.
5.4 Evaporation/concentration apparatus.
5.4.1 Kuderna-Danish (K-D) apparatus.
5.4.1.1 Evaporation flask: 500-mL (Kontes K-570001-0500, or equivalent),
attached to concentrator tube with springs (Kontes K-662750-0012).
5.4.1.2 Concentrator tube: 10-mL, graduated (Kontes K-570050-1025, or
equivalent) with calibration verified. Ground-glass stopper (size 19/22
joint) is used to prevent evaporation of extracts.
5.4.1.3 Snyder column: Three-ball macro (Kontes K-503000-0232, or equivalent).
5.4.1.4 Snyder column: Two-ball micro (Kontes K-469002-0219, or equivalent).
5.4.1.5 Boiling chips.
5.4.1.5.1 Glass or silicon carbide: Approximately 10/40 mesh, extracted
with methylene chloride and baked at 450°C for a minimum of
1 hour.
5.4.1.5.2 PTFE (optional): Extracted with methylene chloride.
5.4.2 Water bath: Heated, with concentric ring cover, capable of temperature control
(+2°C), installed in a fume hood.
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Method 1651A
5.4.3 Sample vials: Amber glass, 1- to 5-mL with PTFE-lined screw- or crimp-cap, to fit
GC autosampler.
5.5 Balances.
5.5.1 Analytical: Capable of weighing 0.1 mg. Calibration must be verified with class S
weights each day of use.
5.5.2 Top-loading: Capable of weighing 10 mg.
5.6 Gas chromatograph (GC): Analytical system with split injection, capillary column,
temperature program with initial and final isothermal holds, and all required accessories,
including syringes, analytical columns, gases, detector, and recorder. The analytical system
shall meet the performance specifications in Section 12.
5.6.1 Column: 30 m (±5 m) long by 0.25 mm (±0.02 mm) i.d., 99% methyl, 1% vinyl,
1.0 jan film thickness, bonded-phase fused-silica capillary (Supelco SPB-1, or
equivalent).
5.6.2 Detector: Flame ionization. This detector has proven effective in the analyses of
drilling fluids for diesel oil and was used to develop the method performance
statements in Section 16. Guidelines for using alternative detectors are provided in
Section 11.1.
5.7 GC data system: Shall collect and record GC data, store GC runs in magnetic memory or on
magnetic disk or tape, process GC data, compute peak areas, store calibration data including
retention times and response factors, identify GC peaks through retention times, and compute
concentrations.
5.7.1 Data acquisition: GC data shall be collected continuously throughout the analysis and
stored on a magnetic storage device.
5.7.2 Response factors and calibration curves: The data system shall be used to record and
maintain lists of response factors and multi-point calibration curves (Section 7).
Computations of relative standard deviation (coefficient of variation, CV) are used for
testing calibration linearity. Statistics on initial (Section 8.2) and ongoing
(Section 12.5) performance shall be computed and maintained.
5.7.3 Data processing: The data system shall search, locate, identify, and quantify the
compounds of interest in each GC analysis. Software routines shall be employed to
compute and record retention times and peak areas. Displays of chromatograms and
library comparisons are required to verify results.
6. REAGENTS
6.1 Sodium sulfate: Anhydrous, ACS grade, granular.
6.2 Methylene chloride: Nanograde or equivalent.
6.3 Reagent water: Water in which the compounds of interest and interfering compounds are not
detected by this method.
6.4 Internal standard: Dissolve 1.0 g of 1,3,5-trichlorobenzene (TCB, Kodak No. 1801 or
equivalent) in 100 mL methylene chloride. Store in glass and tightly cap with PTFE-lined lid
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Method 1651A
to prevent loss of solvent by evaporation. Label with the concentration and date. Mark the
level of the meniscus on the bottle to detect solvent loss.
6.5 Calibration standards: Calibration standards are prepared from the same diesel oil expected to
be in the sample; otherwise, No. 2 diesel oil is used.
6.5.1 Prepare stock solutions of calibration standards at the concentrations shown in
Table 1. Weigh the appropriate amount of oil into a tared 10-mL volumetric flask
and dilute to volume with methylene chloride. Label each flask with the concentration
and date.
6.5.2 Using a micropipette or microsyringe, transfer 100 /xL of each reference standard
solution (Section 6.5.1) to a GC injection vial. Add 100 /*L of the TCB internal
standard (Section 6.4) to each vial and mix thoroughly. Calibration standards are
made fresh daily to avoid solvent loss by evaporation.
6.6 QC standard: Used for tests of initial (Section 8.2) and ongoing (Section 12.5) performance.
Prepare a reference mud sample containing 20,000 mg/kg of diesel by adding 20.0 mg
(±0.2 mg) of No. 2 diesel oil and 10.0 g (+0.1 g) of EPA Generic Mud No. 8 to a clean
retort cup (see Section 10.1). Mix the mud and diesel oil thoroughly with a metal spatula.
7. CALIBRATION
7.1 Establish gas chromatographic operating conditions given in Table 2. Verify that the GC
meets the performance criteria (Section 12) and the estimated detection limit (Section 1.4).
The gas chromatographic system is calibrated using the internal standard technique.
NOTE: Because each GC is slightly different, it may be necessary to adjust the
operating conditions (carrier gas flow rate and column temperature and temperature
program) slightly until the retention times in Table 3 are met.
7.2 Internal standard calibration procedure: 1,3,5-Trichlorobenzene (TCB) has been shown to be
free of interferences from the diesel oils tested in the development of this method. Check for
acceptability by injecting 0.5 fjL of the internal standard solution (Section 6.4) into the
GC/FID. If a major peak other than the TCB peak appears in the chromatogram, interference
with the peaks used for determination of diesel oil may occur. In this case, the analyst must
choose an alternative internal standard that is free from interferences.
7.2.1 Inject 1 ^iL of each calibration standard containing the internal standard (Table 1 and
Section 6.5.2) into the GC/FID. The TCB will elute approx 8.5 minutes after
injection. For the GC/FID used in the development of this method, the TCB internal
standard peak was 30 to 50% of full scale at an attenuator setting of 8 x 10"n amp.
7.2.2 Individual response factors.
7.2.2.1 Tabulate the peak area responses against concentration for each of the ten
largest peaks in the chromatogram (excluding the solvent peak, the internal
standard peak, and any peaks that elute prior to the internal standard peak).
(See Section 13 for guidance on peak selection.) Calculate response
factors (RF) for each peak using the following equation:
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Method 1651A
Equation 1
RF (/
where:
As = Area of the peak to be measured
C^ = Concentration of the internal standard, in mglkg
A^ = Area of the internal standard peak
C = Concentration of the peak to be measured, in mglkg
7.2.2.2 If the RF is constant (< 15% CV) over the calibration range (Table 1), 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/AU vs. RF.
7.2.2.3 Calibration verification: For each peak, the average RF or a point on the
calibration curve shall be verified on each working day by the
measurement of one or more calibration standards. If the RF for any peak
varies from the RF obtained in the calibration by more than +15%, the
test shall be repeated using a fresh calibration standard. Alternatively, a
new calibration curve shall be prepared.
7.2.3 Combined response factor: To reduce the error associated with the measurement of a
single peak, a combined response factor is used for computation of the diesel oil
concentration. This combined response factor is the sum of the individual response
factors as given in Equations 2 or 3:
Equation 2
RF Combined = RF(l) + RF(2)... + RF(n)
Equation 3
RF Combined =
[A'm + A* (2)"'+ A'
where:
n = Number of individuals peaks
Asm...A(rti = Areas of the individual peaks
C^ = Concentration of the internal standard, in mglkg
A^ = Area of the internal standard peak
Cs = Concentration of the peak to be measured, in mglkg
8
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Method 1651A
8. QUALITY ASSURANCE/QUALITY CONTROL
8.1 Each laboratory that uses this method is required to operate a formal quality assurance
program (Reference 6). The minimum requirements of this program consist of an initial
demonstration of laboratory capability, an ongoing analysis of standards and blanks as a test of
continued performance, analyses of spiked samples to assess accuracy, and analysis of
duplicates to assess precision. Laboratory performance is compared to established
performance criteria to determine if the results of analyses meet the performance
characteristics of the method.
8.1.1 The analyst shall make an initial demonstration of the ability to generate acceptable
accuracy and precision with this method. This ability is established as described in
Section 8.2.
8.1.2 The analyst is permitted to modify this method to improve separations or lower the
costs of measurements, provided all performance requirements are met. Each time a
modification is made to the method, the analyst is required achieve the estimated
detection limit (Section 1.4) and to repeat the procedure in Section 8.2 to demonstrate
method performance.
8.1.3 Analyses of spiked samples are required to demonstrate method accuracy. The
procedure and QC criteria for spiking are described in Section 8.3.
8.1.4 Analyses of duplicate samples are required to demonstrate method precision. The
procedure and QC criteria for duplicates are described in Section 8.4.
8.1.5 Analyses of blanks are required to demonstrate freedom from contamination. The
procedures and criteria for analysis of a blank are described in Section 8.5.
8.1.6 The laboratory shall, on an ongoing basis, demonstrate through calibration verification
and analysis of the QC standard (Section 6.6) that the analysis system is in control.
These procedures are described in Section 12.
8.1.7 The laboratory shall maintain records to define the quality of data that is generated.
Development of accuracy statements is described in Sections 8.3.4 and 12.5.
8.2 Initial precision and accuracy: To establish the ability to generate acceptable precision and
accuracy, the analyst shall perform the following operations.
8.2.1 Retort, extract, concentrate, and analyze four samples of the QC standard
(Sections 6.6 and 10.1.3) according to the procedure beginning in Section 10.
8.2.2 Using results of the set of four analyses, compute the average recovery (X) in mg/kg
and the standard deviation of the recovery (s) in mg/kg for each sample by the
internal standard method (Sections 7.2 and 14.2).
8.2.3 For each compound, compare s and X with the corresponding limits for initial
precision and accuracy in Table 4. If s and X meet the acceptance criteria, system
performance is acceptable and analysis of samples may begin. If, however, s exceeds
the precision limit or X falls outside the range for accuracy, system performance is
unacceptable. In this event, review this method and the retort manufacturer's
instructions, correct the problem, and repeat the test.
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Method 1651A
8.3 Method accuracy: The laboratory shall spike a minimum of 20% (one sample in each set of
five samples) of all drilling fluid samples. This sample shall be spiked with the diesel oil that
was added to the drilling fluid. If a reference standard of diesel oil that was added to the
drilling fluid is not available, No. 2 diesel oil shall be used for this spike. If doubt of the
identity and concentration of diesel oil in any of the remaining 80% of the samples exists, that
sample shall be spiked to confirm the identity and establish the diesel oil concentration.
8.3.1 The concentration of the spike in the sample shall be determined as follows.
8.3.1.1 If, as in compliance monitoring, the concentration of the oil in the sample
is being checked against a regulatory concentration limit, the spike shall be
at that limit or at 1 to 5 times higher than the background concentration
determined in Section 8.3.2, whichever concentration is higher.
8.3.1.2 If the concentration of the oil in a sample is not being checked against a
limit, the spike shall be at the concentration of the QC standard
(Section 6.6) or at 1 to 5 times higher than the background concentration,
whichever concentration is higher.
8.3.2 Analyze one sample aliquot to determine the background concentration (B) of total oil
and of diesel oil. If necessary, prepare a standard solution appropriate to produce a
level in the sample at the regulatory concentration limit or at 1 to 5 times the
background concentration (per Section 8.3.1). Spike a second sample aliquot with the
standard solution and analyze it to determine the concentration after spiking (A) of
each analyte. Calculate the percent recovery (P) of total oil and of diesel oil using
Equation 4:
Equation 4
p = IQO(A-B)
T
where:
A = Concentration of analyte after spiking
B = Background concentration of total oil and diesel oil
T = True value of the spike
8.3.3 Compare the percent recovery for total oil and for diesel oil with the corresponding
QC acceptance criteria in Table 4. If the results of the spike fail the acceptance
criteria, and the recovery of QC standard in the ongoing precision and recovery test
(Sections 10.1.3 and 12.5) is within the acceptance criteria in Table 4, an interference
may be present (see Sections 3 and 15 for identification of interferences). In this case,
the result may not be reported for regulatory compliance purposes. If, however, the
results of both the spike and the ongoing precision and recovery test fail the
acceptance criteria, the analytical system is judged to be out of control and the
problem must be immediately identified and corrected and the sample set reanalyzed.
8.3.4 As part of the QA program for the laboratory, method accuracy for samples shall be
assessed and records shall be maintained. After the analysis of five spiked samples in
which the recovery passes the test in Section 8.3, compute the average percent
10
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Method 1651A
recovery (P) and the standard deviation of the percent recovery (sp). Express the
accuracy assessment as a percent recovery interval from P 2sp to P + 2sp. For
example, if P = 90% and sp = 10% for five analyses of diesel oil, the accuracy
interval is expressed as 70 to 110%. Update the accuracy assessment on a regular
basis (e.g., after each five to ten new accuracy measurements).
8.4 The laboratory shall analyze duplicate samples for each drilling fluid type at a minimum of
20% (one sample for each set of five samples). A duplicate sample shall consist of a
well-mixed, representative aliquot of the sample.
8.4.1 Analyze one sample in the set in duplicate per the procedure beginning in Section 10.
8.4.2 Compute the relative percent difference (RPD) between the two results per the
following equation:
Equation 5
RPD = —Lj iL x 100
(D, + D2)/2
where'.
Dj = Concentration of diesel oil in the sample
D2 = Concentration of diesel oil in the second (duplicate) sample
8.4.3 The relative percent difference for duplicates shall meet the acceptance criteria in
Table 5. If the criteria are not met, the analytical system shall be judged to be out of
control, and the problem must be immediately identified and corrected and the sample
set reanalyzed.
8.5 Blanks: Reagent water blanks are analyzed to demonstrate freedom from contamination.
8.5.1 Extract and concentrate a reagent water blank initially and with each sample set
(samples started through the analysis on the same day, to a maximum of five
samples). Analyze the blank immediately after analysis of the QC standard
(Section 6.6) to demonstrate freedom from contamination.
8.5.2 If any of the components of diesel oil or any potentially interfering compound is
detected in a blank, analysis of samples is halted until the source of contamination is
eliminated and a blank shows no evidence of contamination.
8.6 Compare the concentration of the total oil (Section 14.1.2) determined gravimetrically with the
diesel oil concentration determined by GC/FID (Section 14.2.2). If the diesel oil concentration
exceeds the gravimetric oil concentration, the analysis has been performed improperly.
Correct the error or repeat the sample analysis beginning with Section 10.
8.7 The specifications contained in this method can be met if the apparatus used is calibrated
properly, then maintained in a calibrated state. The standards used for initial precision and
recovery (IPR, Section 8.2) and ongoing precision and recovery (OPR, Section 12.5) should
be identical, so that the most precise results will be obtained. The GC instrument will provide
11
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Method 1651A
the most reproducible results if dedicated to the settings and conditions required for the
analyses given in this method.
8.8 Depending on specific program requirements, field replicates and field spikes ofdiesel oil into
samples may be required to assess the precision and accuracy of the sampling and sample
transportation techniques.
9. SAMPLE COLLECTION, PRESERVATION, AND HANDLING
9.1 Collect drilling fluid samples in wide-mouth glass containers following conventional sampling
practices (Reference 7).
9.2 Samples must be representative of the entire bulk drilling fluid. In some instances, composite
samples may be required.
9.3 Maintain samples at 0 to 4°C from the time of collection until extraction.
9.4 Sample and extract holding times for this method have not yet been established. However,
based on tests of wastewater for the analytes determined in this method, samples shall be
extracted within seven days of collection and extracts shall be analyzed within 40 days of
extraction.
9.5 As a precaution against analyte and solvent loss or degradation, sample extracts are stored in
glass bottles with PTFE-lined caps, in the dark, at -20 to -!0°C.
10. SAMPLE EXTRACTION AND CONCENTRATION
10.1 Retort.
10.1.1 Tare the retort sample cup and cap to the nearest 0.1 g. Transfer a well-homogenized
and representative portion of the drilling fluid to be tested into the sample cup. Do
not fill the retort cup to the top so that excess sample must be wiped off. Place the
cap on the cup and reweigh. Record the weight of the sample to the nearest 0.1 g.
NOTE: On agitation, most drilling fluids entrain air as small bubbles. The extent of
air entrainment is uncertain and is difficult to detect when the mud is poured into the
retort cup. By weighing the drilling fluid, the quantitative detection ofdiesel oil is
improved. In addition, by using a gravimetric measurement of the amount of sample,
the retort cup does not need to be completely filled. This procedure avoids the error
that occurs when the cup is filled and the oil rises to the surface of the sample and must
be wiped off (as occurs if the manufacturer's instructions are followed), thus resulting
in a loss of oil.
10.1.2 Follow the manufacturer's instructions for retort of the drilling fluid. Substitute 6 g
of loosely packed glass wool for the steel wool in the manufacturer's instructions and
distill the sample into a glass receiver. The presence of solids in the distillate require
that the distillation be rerun starting with a new portion of sample, Placing more
glass wool in the retort expansion chamber, per the manufacturer's instructions, will
help prevent the solids from being carried over in the distillation.
12
-------
Method 1651A
10.1.3 QC standard: Used for tests of initial (Section 8.2) and ongoing (Section 12.5)
precision and accuracy. For the initial set of four samples (Section 8.2) and for each
set of samples started through the retort process on the same working day (to a
maximum of five), prepare a QC sample as follows.
10.1.3.1 Place the QC standard (Section 6.6) in the retort cup beginning in
Section 10.1.
10.1.3.2 Analyze the QC standard beginning with Section 10.1.2 then proceeding to
Section 10.2.
10.1.4 Blank: For the initial set of four samples (Section 8.2) and for each set of samples
started through the retort process on the same working day (to a maximum of five),
prepare a blank as follows.
10.1.4.1 Place 10 mL of reagent water in a clean, tared retort cup and weigh to
the nearest mg. Record the weight of the reagent water.
10.1.4.2 Analyze the blank beginning with Section 10.1.2 then proceeding to
Section 10.2.
10.2 Extraction and drying.
10.2.1 After the distillation is complete, pour the retort distillate into a 60-mL separatory
funnel. Quantitatively rinse the inner surfaces of the retort stem and condenser with
methylene chloride into the separatory funnel. Rinse the receiver with two full
receiver volumes of methylene chloride and add to the separatory funnel.
10.2.2 Stopper and shake the funnel for one minute, with periodic venting to prevent a
buildup of gas pressure. Allow the layers to separate.
10.2.2 Prepare a glass filtering funnel by plugging the bottom with a piece of glass wool and
pouring in 1 to 2 inches of anhydrous sodium sulfate. Alternatively, a drying column
may be used. Wet the funnel or column with a small portion of methylene chloride
and allow the methylene chloride to drain to a waste container.
10.2.3 Place the glass filtering funnel or drying column into the top of a Kuderna-Danish
(K-D) flask equipped with a preweighed 10-mL receiving flask. Add a preweighed
boiling chip to the receiving flask. Drain the methylene chloride (lower) layer into
the glass filtering funnel or drying column, and collect the extract in the K-D flask.
10.2.4 Repeat the methylene chloride extraction twice more, rinsing the receiver with two
thorough washings each time and draining each methylene chloride extract through the
funnel or drying column into the K-D flask.
10.3 Concentration.
10.3.1 Place a Snyder column on the K-D flask. Prewet the Snyder column by adding about
1 mL of methylene chloride to the top. Place the K-D apparatus on a hot water bath
(60 to 65°C) so that the concentrator tube is partially immersed in the hot water and
the entire lower rounded surface of the flask is bathed with hot vapor. Adjust the
vertical position and the water temperature as required to complete the concentration
in 15 to 20 minutes. At the proper rate of distillation, the balls of the column will
actively chatter but the chambers will not flood with condensed solvent. Concentrate
13
-------
Method 1651A
the sample until it is free of methylene chloride. Remove the K-D apparatus from the
hot water bath and allow to cool.
10.3.2 Weigh and record the final weight of the receiving flask.
10.3.3 Dissolve the oil in methylene chloride and adjust the final volume to 0.40 mL
(400 /xL). If the extract did not concentrate to a final volume of 0.40 mL or less,
adjust the final volume to 4.0 mL.
11. GAS CHROMATOGRAPHY
11.1 Table 3 lists the retention times that can be achieved under the conditions in Table 2 for the
n-alkanes of interest. The chromatogram in Figure 1 can be used as guidance in peak selection
when peaks other than the n-alkanes are used. Other retort devices, columns, chromatographic
conditions, or detectors may be used if the estimated detection limits (Section 1.4) and the
requirements of Section 8.2 are met.
11.2 Using a micropipette or microsyringe, transfer equal 100-/iL volumes of the sample extract or
QC standard extract (Section 10.3.3) and the TCB internal standard solution (Section 6.4) into
a GC injection vial. Cap tightly and mix thoroughly.
11.3 Inject 1 [iL of the sample extract or reference standard into the GC using the conditions in
Table 2.
11.4 Begin data collection and the temperature program at the time of injection.
11.5 If the area of any peak exceeds the calibration range of the system, make a ten-fold dilution of
the extract (Section 10.3.3), mix a 100-/*L aliquot of this dilute extract with 90 /iL of the
internal standard solution (Section 6.4), and reanalyze.
12. SYSTEM AND LABORATORY PERFORMANCE
12.1 At the beginning of each 8-hour shift during which analyses are performed, GC calibration is
verified. For these tests, analysis of a calibration standard prepared from the 300-mg/mL
reference standard (Section 6.5.2) shall be used to verify all performance criteria. Adjustment
and/or recalibration (per Section 7) shall be performed until all performance criteria are met.
Only after all performance criteria are met may the QC standard, blank, and samples be
analyzed.
12.2 Retention times.
12.2.1 Retention time of the internal standard: The absolute retention time of the TCB
internal standard shall be within the range of 7.96 to 8.08 minutes.
12.2.2 Relative retention times of the n-alkanes: The retention times of the n-alkanes relative
to the TCB internal standard shall be within the limits given in Table 3.
12.3 Calibration verification.
12.3.1 Compute the response factor for each peak by the internal standard technique
(Section 7.2).
12.3.2 For each peak, compare the response factor with the response factor from the initial
calibration (Section 7.2.2). If all response factors are within ± 15% of their
respective values in the initial calibration, system calibration has been verified. If
14
-------
Method 16 51A
not, prepare a fresh calibration standard and repeat the test (Section 12.1), or
recalibrate (Section 7).
12.4 Multiple GC peaks: Each peak selected for use in the calculation shall be a single, distinct GC
peak.
12.5 Ongoing precision and accuracy.
12.5.1 Compute the total oil concentration and the concentration of diesel oil in the QC
standard in each sample set (Section 10.1.3) prior to analysis of any sample in the set.
12.5.2 Compare the concentration with the QC limit in Table 4. If the concentrations of total
oil and of diesel oil in the QC standard meet the acceptance criteria, system
performance is acceptable and analysis of samples may proceed. If, however, the
concentrations do not meet the acceptance criteria, system performance is unac-
ceptable. In this event, correct the problem, reprocess the sample set (Section 10),
and repeat the ongoing precision and accuracy test (Sections 10.1.3 and 12.5).
12.5.3 Add results that pass the specifications in Section 12.5.2 to initial and previous
ongoing data. Update QC charts to form a graphic representation of continued
laboratory performance. Develop statements of laboratory accuracy for total oil and
diesel oil in drilling fluids by calculating the average percent recovery (R) and the
standard deviation of percent recovery (sr). Express the accuracy statement as a
recovery interval from R 2sr to R + 2sr. For example, if R = 95% and sr = 5%,
the accuracy is 85 to 105%.
13. QUALITA TIVE DETERMINA TION
If less than ten of the GC peaks used to calculate the combined RF (Section 7.2.2) are present in the
sample and the QC tests (Sections 8 and 12) for the sample set are acceptable, diesel oil is not present
in the sample. If the ten GC peaks used to calculate the combined RF are present in the analysis of
the sample, diesel oil is identified by comparing the relative retention times and relative areas of
peaks to the respective peaks in the diesel oil calibration standard. If either the relative retention
times or the relative areas disagree and the QC tests (Sections 8 and 12) are acceptable, then an
interference is suspected, and Method 1625 (Revision C or greater) shall be used to determine the
presence of the components of diesel oil in the sample.
13.1 Relative retention times: If the n-alkane peaks are used for identification of diesel oil, the
relative retention times shall agree within the limits in Table 3. If peaks other than the
n-alkanes are used, the relative retention times shall agree within +2% of the retention times
of the peaks used for calibration (Section 7).
13.2 Distribution of peak area ratios (Reference 8): Diesel oil is further identified by comparing
the distribution of the area ratios of ten peaks in the chromatogram of the diesel oil calibration
standard (Section 6.5) to these same ratios in the chromatogram of the sample extract.
13.2.1 Using the largest peak of the ten as reference, divide the area of each of the other
nine peaks by the area of this largest peak. Repeat this division process for the same
ten peaks in the calibration standard.
13.2.2 If all ratios agree within ±21%, diesel has been positively identified. The quantity of
diesel oil is then determined per Section 14.
15
-------
Method 1651A
14. QUANTITATIVE DETERMINATION
14.1 Total oil by gravimetry.
14.1.1 Subtract the weight of the preweighed receiving flask and boiling chip
(Section 10.2.3) from the final weight of the receiving flask (Section 10.3.2).
14.1.2 Calculate the concentration of total oil in the sample using the following equation:
Equation 6
W,
C (mg/kg) = _/ x 1000
where;
W, = Final weight of oil, in mg (from Section 14.1.1)
Ws - Wet weight of sample, in grams (from Section 10.1.1)
14.2 Diesel oil by gas chromatography.
14.2.1 Compute the concentration of diesel oil in the sample extract using the combined
response factor given in Section 7.3.3 for the ten largest peaks chosen in Section 13
using the following equation:
Equation 7
Ccx (mg/mL) =
(A^RF Combined)
where:
Cex = Concentration of the oil in the extract
^ = Concentration of the internal standard, in mg/mL
As = Area of the peak to be measured
A.a = Area of the internal standard peak
(For RF Combined, see Equations 2 and 3)
14.2.2 Calculate the concentration of diesel oil (in mg/kg) in the sample as follows:
Equation 8
C (mg/kg) = —-—— x 1000
j
where:
CM = Concentration of the oil in the extract
Vex = Final extract volume, in mL (from Section 10.3.3 or 14.2.3)
W = Wet weight of sample, in g (from Section 10.1.1)
16
-------
Method 1651A
14.2.3 If area of any peak in the chromatographic pattern exceeds the calibration range of the
GC, the extract is diluted by a factor of 10 with methylene chloride, 100 ^L is
withdrawn and mixed with 90 pL of the internal standard solution (Section 6.4), and
the diluted extract is reanalyzed.
14.3 Results of analyses of diesel oil in drilling fluids are reported in units of mg/kg (wet weight) to
three significant figures. Results for samples that have been diluted are reported at the least
dilute level at which the peak areas are within the calibration range (Section 14.2.3).
7 5. COMPLEX SA MPLES
15.1 The most common interference in the determination of diesel oil are from mineral oil in
drilling fluids, proprietary additives, and naturally occurring hydrocarbons from crude-oil-
bearing formations.
15.2 The presence of mineral oil or other interfering oils and additives can often be determined by
comparing the pattern of chromatographic peaks in the sample with the patterns of
chromatographic peaks in the reference standard (Sections 6.5 and 10.1.3) and in the spiked
sample (Section 8.3).
15.3 In cases where there is a mixture of diesel and mineral oil, the analyst may have to choose
some of the smaller early- or late-eluting peaks present in the chromatographic pattern of the
diesel oil, and not present in the chromatographic pattern of the mineral oil, to determine the
diesel content. Quantification using these peaks is performed by using these peaks for
calibration (Section 7) and for determination of the final concentration (Section 14).
15.4 Method 1625 (Revision C or later) shall be used to determine the components of diesel oil if
diesel oil cannot be determined by this method in the presence of these interferences. If this
method and Method 1625 are both used to determine the presence of the components of diesel
oil, the results from the determination using Method 1625 take precedence over the results
from the determination using this method.
16. METHOD PERFORMANCE
16.1 This method was developed by two laboratories that tested for diesel oil in drilling fluids
(mainly drilling muds) over a two-year period. The performance data for this method are
based on the performance of the method in these two laboratories (Reference 9).
16.2 The most commonly occurring drilling fluid in the tests of this method was a seawater
lignosulfonate mud (EPA Generic Mud No. 8). The estimated detection limit for diesel oil in
this mud is 100 mg/kg.
17
-------
Method 1651A
References
1. Brown, John S. "Organic Chemical Characterization of Diesel and Mineral Oils Used as
Drilling Mud Additives." Proceedings of Tenth Annual Analytical Symposium, USEPA,
Industrial Technology Division (WH-552), 401 M St., S.W., Washington, DC 20460: March
19-20, 1986.
2. Brown, John S. "Final Report for Research Program on: Organic Chemical Characterization
of Diesel and Mineral Oils used as Drilling Mud Additives." Phase II, Contract Reference
Agreement No. 501-P-5476R, to Offshore Operators Committee, Environmental
Subcommittee. Houston, TX. (Prepared by Battelle Ocean Science and Technology
Department, 397 Washington St., Duxbury, MA 02332.)
3. "Carcinogens—Working With Carcinogens." Department of Health, Education, and Welfare,
Public Health Service, Centers for Disease Control [available through National Technical
Information System, 5285 Port Royal Road, Springfield, VA 22161, document no. PB-
277256]: August 1977.
4. "OSHA Safety and Health Standards, General Industry [29 CFR 1910], Revised."
Occupational Safety and Health Administration, OSHA 2206. Washington, DC: January 1976.
5. "Safety in Academic Chemistry Laboratories (3rd Edition)." American Chemical Society
Publication, Committee on Chemical Safety. Washington, DC: 1979.
6. "Handbook of Analytical Quality Control in Water and Wastewater Laboratories." USEPA,
EMSL-Ci, EPA-600/4-79-019. Cincinnati, OH: March 1979.
7. "Standard Practice for Sampling Water," ASTM Annual Book of Standards, Part 31, D3370-
76, ASTM. Philadelphia, PA: 1980.
8. Boehm, Paul D., and Sauer, Theodor C., "Review and Evaluation of Draft EPA Method 1651
Total Oil and Diesel Oil in Drilling Discharges by Retort, Gravimetry, and GC-FID." Battelle
Ocean Sciences, 397 Washington St., Duxbury, MA 02332: March 4, 1988.
9. Rushneck, D.R., and Eynon, B.P., "Precision and Recovery Analysis of DPMP Diesel
Measurements." Memorandum to Dennis Ruddy, USEPA, Industrial Technology Division
(WH-552), 401 M. St. S.W., Washington, DC 20460 (23 August 1987, draft).
18
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Method 1651A
Table 1. Concentration of Calibration Standards
Expected Concen- Wt of Diesel oil in Concentration in
tration in Sample 10 mL volumetric* standard solution
(mg/kg) (g) (mg/mL)
50,000 use undiluted oil
30,000 7.6 760
10,000 3.0 300
5,000 1.5 150
*Weigh oil to the nearest mg
Table 2. Gas Chromatographic Operating Conditions*
Injection port, transfer line, and detector temperatures: 275 °C
Column temperature program:
Initial temperature: 90°C
Initial time: 0 minutes
Ramp: 90-250°C @ 5°C per minute
Final temperature: 250°C
Final hold: 10 minutes, or until all peaks have eluted
Carrier gas and flow rates:
Carrier: Nitrogen or helium
Velocity: 20-40 cm/sec @ 90 °C
Split ratio: 0-120:1**
Makeup gas: As required by manufacturer
Hydrogen and air flow rates: As specified by manufacturer
Detector amplifier settings: 10"" amp full scale. Attenuation is adjusted so that the highest
peaks are on scale in the most concentrated standard.
Recorder: Chart speed of 1-2 cm/min (fixed).
* Conditions are approximate and can be adjusted to meet the performance criteria in Section 12
(see the note in Section 7.1)
** Lower split ratios may give more reproducible results
19
-------
Method 1651A
Table 3. Retention Times and Relative Retention Time Limits for Major
Components of Diesel Oil
Retention Time
Compound
TCB
n-C12
n-C13
n-C14
n-C1B
n-C16
n-C17
n-C18
n-C19
n-C20
n-C21
n-C22
n-C23
n-C24
Mean
(minutes)
8.0
9.9
12.6
15.3
17.9
20.4
22.9
25.2
27.3
29.4
31.5
33.4
35.3
37.1
Relative
1.00-1.00
1.22-1.24
1.55-1.57
1.89-1.92
2.21-2.25
2.52-2.56
2.82-2.88
3.12-3.15
3.39-3.43
3.66-3.71
3.90-3.97
4.14-4.21
4.37-4.45
4.58-4.69
Table 4. QC Acceptance Criteria for Precision and Recovery
Analyte
Total oil by grav
Diesel oil by GC
Test concentration
(mg/kg)
20,000
n*
20,000
n*
Limit for s
(mg/kg)
3,400
0.17n
3,600
0.18n
Range for X
(mg/kg)
18,000-23,700
0.88n-1.16n
17,200-20,300
0.80n-1.08n
Range for P
(mg/kg)
16,700-24,900
0.82n-1.22n
13,600-21,400
0.73n-1.14n
* For other test concentrations in the range of 1,000-50,000 mg/kg, assuming a spike to
background ratio of 5:1.
Table 5. QC Acceptance Criteria for Duplicates
Concentration
Detected
(mg/kg)
500
750
1,000
2,000
5,000
10,000
20,000
50,000
Relative % Difference
Total Oil
36
30
28
24
21
21
20
20
Diesel Oil
94
68
54
34
22
18
16
15
20
-------
Method 1651A
Diesel Oil in Drilling Mud
Reference Diesel Oil
Mineral Oil
A52-010-4
Figure 1. Gas Chromatography of Diesel Oil in Drilling Mud, Reference Diesel Oil, and
Mineral Oil
21
-------
Method 1654, Revision A
PAH Content of Oil by
HPLC/UV
-------
Method 1654, Revision A
PAH Content of Oil by HPLC/UV
1. SCOPE AND APPLICA TION
1.1 This method is designed to determine the polynuclear aromatic hydrocarbon (PAH) content of
oil by high-performance liquid chromatography (HPLC) with an ultra-violet absorption (UV)
detector. The PAH content is measured and reported as phenanthrene.
1.2 This method is for use in the Environmental Protection Agency's (EPA's) survey and
monitoring programs under the Federal Water Pollution Control Act.
1.3 For oil in drilling muds, this method is designed to be used in conjunction with the extraction
procedure in EPA Method 1662.
1.4 The level of PAH in Table 1 typifies the minimum level that can be detected in oil with this
method.
1.5 Any modification of this method beyond those expressly permitted shall be considered as a
major modification subject to application and approval of alternative test procedures under
40 CFR 136.4 and 136.5.
1.6 This method is restricted to use by or under the supervision of analysts experienced in the use
of HPLC systems 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.
2. SUMMARY OF METHOD
2.1 An oil sample is diluted in acetonitrile and a 20-/*L aliquot is injected into the HPLC. The
PAHs are partially separated by HPLC and detected with the UV detector.
2.2 Identification of PAH (qualitative analysis) is performed by comparing the response of the UV
detector to the response during the retention-time range characteristic of the PAH in diesel oil.
PAH is present when a response occurs during this retention-time range.
2.3 Quantitative analysis is performed by calibrating the HPLC with phenanthrene using an
external standard technique, and using the calibration factor to determine the concentration of
PAH in the sample.
2.4 Quality is assured through reproducible calibration and testing of the extraction and HPLC
systems.
3. INTERFERENCES
3.1 Solvents, reagents, glassware, and other sample processing hardware may lead to discrete
artifacts and/or elevated baselines causing misinterpretation of chromatograms.
3.1.1 All materials used in the analysis shall be demonstrated to be free from interferences
by running method blanks initially and with each sample batch (samples started
through the extraction process at the same time, to a maximum often). Specific
selection of reagents and purification of solvents by distillation in all-glass systems
may be required.
25
-------
Method 1654A
3.1.2 Glassware and, where possible, reagents are cleaned by solvent rinse and/or baking at
450°C for a minimum of 1 hour.
3.2 When used in conjunction with Method 1662, blanks extracted in that method are treated as an
integral part of this method.
3.3 Interferences co-extracted from samples may vary from source to source, depending on the
diversity of the site being sampled.
4. SAFETY
4.1 The toxicity or carcinogenicity of each compound or reagent used in this method has not been
precisely defined; however, each chemical should be treated as a potential health hazard.
Exposure to these chemicals must be reduced to the lowest possible level.
4.2 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 safety data sheets (MSDSs) should also be made available to all personnel involved in
the chemical analysis. Additional information on laboratory safety can be found in
References 1 through 3.
4.3 Methylene chloride has been classified as a known health hazard. All steps in this method
which involve exposure to this compound shall be performed in an OSHA-approved fume
hood.
5. APPARATUS AND MATERIALS
NOTE: Brand names, suppliers, and part numbers are for illustrative purposes only.
No endorsement is implied. Equivalent performance may be achieved using apparatus
and materials other than those specified here, but demonstration of equivalent
performance meeting the requirements of this method is the responsibility of the
laboratory.
5.1 Equipment for glassware cleaning.
5.1.1 Laboratory sink with overhead fume hood.
5.1.2 Kiln: Capable of reaching 450°C within 2 hours and holding 450°C within + 10°C,
with temperature controller and safety switch (Cress Manufacturing Co, Sante Fe
Springs, CA, B31H or X31TS, or equivalent).
5.2 Equipment for sample preparation.
5.2.1 Laboratory fume hood.
5.2.2 Analytical balance: Capable of weighing 0.1 mg.
5.2.3 Glassware.
5.2.3.1 Disposable pipettes: Pasteur, 150 mm long by 5 mm i.d. (Fisher Scientific
13-678-6A, or equivalent).
5.2.3.2 Glass pipettes: 1.0- and 10-mL, accurate to 1% or better.
5.2.3.3 Volumetric flasks: Glass, 10- and 100-mL.
26
-------
Method 1654A
5.2.4 Sample vials: Amber glass, 2- to 5-mL with PTFE-lined screw-cap, to fit HPLC
autosampler.
5.3 High-performance liquid chromatograph (HPLC): An analytical system complete with pumps,
sample injector, column oven, and ultra-violet (UV) detector.
5.3.1 Pumping system: Capable of isocratic operation and producing a linear gradient from
50% water/50% acetonitrile to 100% acetonitrile in 10 minutes (Waters 600E, or
equivalent).
5.3.2 Sample injector: Capable of automated injection of up to 30 samples (Waters 700, or
equivalent).
5.3.3 Column oven: Capable of operation at room ambient to 50°C (Waters TCM, or
equivalent).
5.3.4 Column: Two C18 columns, 150 mm long by 4.6 mm i.d., 300 angstroms (Vydac
201 TP5415, or equivalent) connected in series, preceded by one C18 guard column,
30 mm long by 4.6 mm i.d., 300 angstroms (Vydac 201 GCC54T, or equivalent),
operated at the conditions shown in Table 1.
5.3.5 Detector: UV operated at 254 nm (Waters 490E, or equivalent).
5.4 Data system.
5.4.1 Data acquisition: The data system shall collect and record LC peak areas and
retention times on magnetic media.
5.4.2 Calibration: The data system shall be used to calculate and maintain lists of
calibration factors (response divided by concentration) and multi-point calibration
curves. Computations of relative standard deviation (coefficient of variation) are used
to test calibration linearity.
5.4.3 Data processing: The data system shall be used to search, locate, identify, and
quantify the compounds of interest in each analysis. Displays of chromatograms are
required to verify results.
5.4.4 Statistics on initial (Section 8.2) and ongoing (Section 12.6) performance shall be
computed and maintained.
6. REAGENTS
6.1 Solvents.
6.1.1 Sample preparation: Methylene chloride, distilled in glass (Burdick and Jackson, or
equivalent).
6.1.2 HPLC: Methanol, acetonitrile, and water, HPLC quality.
6.2 Standards: Purchased as solutions or mixtures with certification to their purity, concentration,
and authenticity, or prepared from materials of known purity and composition. If compound
purity is 96% or greater, the weight may be used without correction to compute the
concentration of the standard. If PAH in oil from drilling mud is to be tested, the diesel oil
standard used in this method should be from the oil used on the drilling rig from which the
mud sample is taken. If this oil is not available, No. 2 diesel oil from a local source may be
substituted.
27
-------
Method 1654A
6.2.1 Stock solutions: Prepare in methanol or acetonitrile for injection into the HPLC.
Observe the safety precautions in Section 4.
6.2.1.1 Diesel oil (1.25 mg/mL): If QC extracts from Method 1662 are to be
tested, use the oil that was spiked to produce these extracts. Weigh
125 mg of diesel oil to three significant figures in a 100-mL ground-glass-
stoppered volumetric flask and fill to the mark with acetonitrile. After the
oil is completely dissolved, transfer the solution to a clean 150-mL bottle
with PTFE-lined cap.
6.2.1.2 Polynuclear aromatic hydrocarbons—naphthalene, phenanthrene, and
indeno[l,2,3-o/]pyrene: Dissolve an appropriate amount of reference
material in a suitable solvent. For example, weigh 10.0 mg of naphthalene
in a 10-mL volumetric flask and fill to the mark with methanol. After the
naphthalene is completely dissolved, transfer the solution to a 15-mL vial
with PTFE-lined cap.
6.2.1.3 Stock solutions should be checked for signs of degradation prior to the
preparation of calibration or performance test standards.
6.2.2 PAH calibration standards (CAL): Dilute and mix the stock solutions
(Section 6.2.1.2) in acetonitrile to produce the calibration standards shown in Table 2.
The three solutions permit the response of phenanthrene to be measured as a function
of concentration, and naphthalene and indeno[l,2,3-o/]pyrene permit the retention-
time window for PAH to be defined. The medium-level solution is used for
calibration verification (Section 12.2).
6.2.3 Precision and recovery standard: The stock solution of diesel oil (Section 6.2.1.1) is
used for initial precision and recovery (IPR; Section 8.2) and ongoing precision and
recovery (OPR; Section 12.6).
6.2.4 Stability of solutions.
6.2.4.1 When not being used, standards are stored in the dark at -20 to -10°C in
screw-capped vials with PTFE-lined lids. A mark is placed on the vial at
the level of the solution so that solvent loss by evaporation can be
detected. The vial is brought to room temperature prior to use. Any
precipitate is redissolved and solvent is added if solvent loss has occurred.
6.2.4.2 Standard solutions used for quantitative purposes (Sections 6.2.1 through
6.2.3) shall be analyzed within 48 hours of preparation and on a monthly
basis thereafter for signs of degradation. Standards will remain acceptable
if the peak area remains within +15% of the area obtained in the initial
analysis of the standard.
7. CALIBRATION
7.1 Assemble the HPLC and establish the operating conditions in Table 2.
7.2 Retention time adjustment.
7.2.1 Inject 20 \tL of the medium level calibration standard (Table 2).
7.2.2 Locate the three peaks in this standard.
28
-------
Method 1654A
7.2.3 Adjust the initial solvent mixture, the isocratic hold, the gradient, and the final
isocratic hold until the retention times are within ± 1 minute of the retention times
given in Table 2.
7.3 Minimum level: Analyze 20 juL of the low-level calibration standard (Table 2) and verify that
the HPLC instrument meets the minimum level for phenanthrene in Table 1.
7.4 External standard calibration.
7.4.1 Analyze 20 /iL of each calibration standard (Table 2) beginning with the lowest
concentration and proceeding to the highest using to the procedure in Section 11.
7.4.2 Record the areas for the phenanthrene peak and the height of the phenanthrene peak in
the high-level standard.
7.4.3 Compute the ratio of response to amount injected (calibration factor) at each
concentration by dividing the area of the peak by the concentration of the standard
injected. Calculate the mean of the three values to produce an average calibration
factor.
7.4.4 Linearity: If the calibration factor is constant over the three point calibration range
(< 15% relative standard deviation), linearity through the origin can be assumed; if
not, the system shall be recalibrated.
7.5 The average calibration factor is verified on each working 8-hour shift by the measurement of
the medium-level calibration standard (Section 12.5).
7.6 Single-point calibration for diesel oil: Inject the precision and recovery standard
(Section 6.2.3) to produce a single calibration point for diesel oil.
7.6.1 Integrate the area from the retention time of naphthalene (including the leading edge
of the naphthalene peak) through the end of the indeno[l,2,3-of|pyrene peak or until
the detector signal returns to a stable baseline, whichever comes later, as shown in
Figure 1.
7.6.2 Determine the calibration factor for diesel oil by dividing the integrated area
(Section 7.6.1) by the diesel oil concentration (Section 6.2.1.1).
8. QUALITY ASSURANCE/QUALITY CONTROL
8.1 Each laboratory that uses this method is required to operate a formal quality assurance
program (Reference 4). The minimum requirements of this program consist of an initial
demonstration of laboratory capability, an ongoing analysis of standards and blanks as a test of
continued performance, analyses of spiked samples to assess accuracy, and analysis of
duplicates to assess precision. Laboratory performance is compared to established
performance criteria to determine if the results of analyses meet the performance
characteristics of the method. If the determination of PAH is to be made on extracts from
Method 1662, the quality control samples for initial precision and recovery (IPR), spiked
samples, duplicate samples, and ongoing precision and recovery (OPR) samples from Method
1662 shall be substituted for those in the QC tests below, and the specifications in Table 1 for
extracts from Method 1662 shall be met.
29
-------
Method 1654A
8.1.1 The analyst shall make an initial demonstration of the ability to generate acceptable
accuracy and precision with this method. This ability is established as described in
Section 8.2.
8.1.2 The analyst is permitted to modify this method to improve separations or lower the
costs of measurements, provided all performance requirements are met. Each time a
modification is made to the method, the analyst is required to achieve the minimum
level (Section 7.3) and to repeat the procedure in Section 8.2 to demonstrate method
performance.
8.1.3 Analyses of spiked samples are required to demonstrate method accuracy when
extracts from Method 1662 are analyzed. The procedure and QC criteria for spiking
are described in Section 8.3.
8.1.4 Analyses of duplicate samples are required to demonstrate method precision when
extracts from Method 1662 are analyzed. The procedure and QC criteria for
duplicates are described in Section 8.4.
8.1.5 Analyses of blanks are required to demonstrate freedom from contamination. The
procedures and criteria for analysis of a blank are described in Section 8.5.
8.1.6 The laboratory shall, on an ongoing basis, demonstrate through calibration verification
and analysis of the precision and recovery standard that the analysis system is in
control. These procedures are described in Section 12.5 and 12.6.
8.1.7 The laboratory shall maintain records to define the quality of data that is generated.
Development of accuracy statements is described in Sections 8.3.2 and 12.6.4.
8.2 Initial precision and recovery (IPR): The initial precision and recovery test is performed using
the precision and recovery standard. If extracts from Method 1662 are to be analyzed, the
extracts from the initial precision and recovery tests in that method shall be used; otherwise,
the laboratory shall generate acceptable precision and recovery by performing the following
operations.
8.2.1 Using diesel oil, prepare four separate aliquots of the precision and recovery standard
(Section 6.2.3). If extracts from Method 1662 are analyzed, the extracts from the
initial precision and recovery test in that method shall be used. Analyze these
aliquots using the procedure in Section 11.
8.2.2 Using results of the set of four analyses, compute the average recovery (X) of PAH in
mg/mL and the standard deviation of the recovery (s) in mg/mL for each aliquot by
the external standard method (Sections 7.4 and 14.4).
8.2.3 Compare s and X with the corresponding limits for initial precision and recovery in
Table 1. If s and X meet the acceptance criteria, system performance is acceptable
and analysis of oil samples may begin. If, however, s exceeds the precision limit or
X falls outside the range for accuracy, system performance is unacceptable. In this
event, review this method, correct the problem, and repeat the test.
8.3 Method accuracy: If extracts from Method 1662 are to be analyzed, the extract from the
accuracy test in that method shall be used; otherwise, an accuracy test is unnecessary. The
procedure for determining method accuracy is given in Section 8.3 of Method 1662, and the
specification for accuracy is given in Table 1 of this method.
30
-------
Method 1654A
8.3.1 Compare the percent recovery of PAH with the corresponding QC acceptance criteria
in Table 1. If the results of the spike fail the acceptance criteria, and the recovery of
the QC standard in the ongoing precision and recovery test (Section 12.6.3) is within
the acceptance criteria in Table 1, an interference may be present. In this case, the
result may not be reported for regulatory compliance purposes. If, however, the
results of both the spike and the ongoing precision and recovery test fail the
acceptance criteria, the analytical system is judged to be out of control and the
problem shall be identified and corrected, and the sample batch reanalyzed.
8.3.2 As part of the QA program for the laboratory, method accuracy for samples shall be
assessed and records shall be maintained. After the analysis of five spiked samples
in which the recovery passes the test in Section 8.3, compute the average percent
recovery (P) and the standard deviation of the percent recovery (sp). Express the
accuracy assessment as a percent recovery interval from P 2sp to P + 2s,,. For
example, if P = 90% and sp = 10% for five analyses of PAH in diesel oil, the
accuracy interval is expressed as 70 to 110%. Update the accuracy assessment on a
regular basis (e.g., after each five to ten new accuracy measurements).
8.4 Duplicates: If extracts from Method 1662 are to be analyzed, the extracts from the duplicates
test in that method shall be used. The procedure for preparing duplicates is given in Section
8.4 of Method 1662, and the specification for RPD is given in Table 1 of this method. If
extracts from Method 1662 are not to be analyzed, duplicates of the precision and recovery
standard (Section 6.2.3) are analyzed, and the specification for RPD is given for PAH in diesel
oil in Table 1 of this method.
8.4.1 Analyze each of the duplicates per the procedure in Section 11 and compute the
results per Section 14.
8.4.2 Calculate the relative percent difference (RPD) between the two results per the
following equation:
Equation 1
RPD= ID' " °2\ xlOO
(D, + D2)/2
where:
D, = Concentration of diesel oil in the sample
D^ = Concentration of diesel oil in the second (duplicate) sample
8.4.3 The relative percent difference for duplicates shall meet the acceptance criteria in
Table 1. If the criteria are not met, the analytical system is be judged to be out of
control, and the problem must be immediately identified and corrected and the sample
set re-extracted and reanalyzed.
8.5 Blanks: If extracts from Method 1662 are to be analyzed, the extracts from blanks in that
method shall be analyzed in addition to the blanks in this method.
31
-------
Method 1654A
8.5.1 Rinse the glassware used in preparation of the extracts in this method with acetonitrile
and analyze a 20-^L aliquot of the rinsate using the procedure in Section 11 and
compute the results per Section 14.
8.5.2 If PAH is detected in a blank at greater than the method detection limit (MDL) in
Table 1, analysis of samples is halted until the source of contamination is eliminated
and a blank shows no evidence of contamination.
8.6 The specifications contained in this method can be met if the apparatus used is calibrated
properly, then maintained in a calibrated state. The standards used for initial precision and
recovery (IPR, Section 8.2) and ongoing precision and recovery (OPR, Section 12.6) should
be identical, so that the most precise results will be obtained. The HPLC instrument will
provide the most reproducible results if dedicated to the settings and conditions required for
the analyses given in this method.
8.7 Depending on specific program requirements, field replicates and field spikes of diesel oil into
samples may be required when Method 1662 and this method are used to assess the precision
and accuracy of the sampling and sample transportation techniques.
9. SAMPLE COLLECTION, PRESERVATION, AND HANDLING
9.1 Oil samples are collected in 20- to 40-mL vials with PTFE- or aluminum-foil-lined caps and
stored in the dark at -20 to -10°C.
9.2 If extracts from Method 1662 are to be analyzed, the laboratory should be aware that sample
and extract holding times for this method have not yet been established. However, based on
tests of wastewater for the analytes determined in this method, samples shall be extracted
within 7 days of collection and extracts shall be analyzed within 40 days of extraction.
9.3 As a precaution against analyte and solvent loss or degradation, sample extracts are stored in
glass bottles with PTFE-lined caps, in the dark, at -20 to -10°C.
10. DILUTION OF OIL AND EXTRACTS
10.1 Neat oil samples: If oil is received in neat form, it should be diluted to bring the
concentration within the range of the instrument. If the oil is No. 2 diesel oil, the appropriate
concentration will be approximately 2000 /ig/mL. Mineral oils and other oils containing a
lesser PAH content will require less dilution.
10.2 Extracts from Method 1662: If extracts of samples from Method 1662 are to be analyzed,
these extracts (from Section 10.4.2 of that method) are analyzed undiluted unless diesel oil is
known or suspected to be present. Extracts of QC samples (IPR, OPR, matrix spikes, and
duplicates) from Method 1662 are diluted by a factor of 10 to bring them within the range of
the HPLC.
10.3 Dilution of neat oil expected to be diesel oil.
10.3.1 Weigh 100 mg into a 10-mL volumetric flask and dilute to the mark with acetonitrile
to produce a concentration of 10 mg/mL. Stopper and mix thoroughly.
10.3.2 Using a calibrated 1.0-mL volumetric pipette, withdraw 1.0 mL of the solution and
place in a 10-mL volumetric flask. Then withdraw an additional 0.25 mL of the
32
-------
Method 1654A
solution and place in the 10-mL volumetric flask (for a total of 1.25 mL). Fill to the
mark with acetonitrile to produce a concentration of 1.25 mg/mL (1250 jig/mL). This
solution will be near, but not above, the limit of the calibration range and will match
the concentration of the QC samples from Method 1662 (assuming 100% recovery).
7 /. HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY
11.1 Table 2 summarizes the recommended operating conditions for the HPLC. Included in this
table and in Table 1 are retention times and the minimum level that can be achieved under
these conditions. An example of the separation achieved for diesel oil by the multiple HPLC
column system is shown in Figure 1. Other HPLC columns, chromatographic conditions, or
detectors may be used if the requirements for the minimum level (Sections 7.3) and initial
precision and recovery (Section 8.2) are met.
11.2 Calibrate the system as described in Section 7 or verify calibration as described in Section 12.
11.3 Analysis of extracts.
11.3.1 Inject 20 /xL of the sample extract, Method 1662 extract, or diluted QC extract into
the HPLC using a high-pressure syringe or a constant-volume sample-injection loop.
Record the volume injected to the nearest 0.1 /iL.
11.3.2 Upon injection, begin the solvent program used in calibrating the column (Section
7.2.3). Record the signal from the time of injection until the detector returns to a
stable baseline. Return the solvent to the initial conditions.
11.3.3 Using the retention-time data determined during calibration, integrate the area from
the retention time of naphthalene (including the leading edge of the naphthalene peak)
through the end of the indeno[l,2,3-cd]pyrene peak or until the detector signal returns
to a stable baseline, whichever comes later.
11.4 If the height of the response during the period recorded (Section 11.3.2) exceeds the height of
the response for phenanthrene during calibration (Section 7.4.2), dilute the extract by
successive factors of 10 with acetonitrile and reanalyze until the response is within the
calibration range.
12. HPL C SYSTEM AND LABORA TORY PERFORMANCE
12.1 At the beginning of each 8-hour shift during which analyses are performed, HPLC calibration
and system performance are verified. For these tests, analysis of the medium-level calibration
standard (Table 2) and of the diluted extract of the precision and recovery standard
(Section 6.2.3) shall be used to verify all performance criteria. Adjustment and/or
recalibration (per Section 7) shall be performed until all performance criteria are met. Only
after all performance criteria are met may samples and blanks be analyzed.
12.2 Inject 20 /iL of the medium-level calibration standard (Table 2) into the HPLC instrument
according to the procedure in Section 11.
12.3 Retention time: The absolute retention times of the naphthalene, phenanthrene, and
indeno[l,2,3-o/]pyrene peaks shall be within +30 seconds of the respective retention times in
the initial calibration (Section 7.2.3).
33
-------
Method 1654A
12.4 HPLC resolution: Resolution is acceptable if the peak width at half-height of the phenanthrene
peak is less than 30 seconds.
12.5 Calibration verification: Compute the concentration of phenanthrene based on the average
calibration factor (Section 7.4.4). The concentration shall be within the limits in Table 1. If
calibration is verified, system performance is acceptable and analysis of blanks and QC
samples may begin. If, however, the concentration falls outside of the calibration verification
range, system performance is unacceptable. In this case, correct the problem and repeat the
test, or recalibrate (Section 7.4).
12.6 Ongoing precision and recovery (OPR): If the extract is from Method 1662, the OPR standard
from that method shall be used and the specification for the OPR from Method 1662 in
Table 1 shall be met; if not, a sample of diesel oil shall be diluted per the procedure in
Section 10 and shall be used for the OPR test.
12.6.1 Analyze the appropriate OPR standard.
12.6.2 Compute the concentration of PAH in this standard per Section 14.
12.6.3 Compare the concentration with the limits for ongoing precision and recovery in
Table 1. If the concentration is in the range specified, the analytical processes are in
control and analysis of blanks and samples may proceed. If, however, the
concentration is not in the specified range, these processes are not in control. In this
event, correct the problem, re-extract the sample batch if the OPR is from
Method 1662, or redilute the oil sample (per Section 10.3), and repeat the ongoing
precision and recovery test.
12.6.4 Add results which pass the specification in Section 12.6.3 to initial and previous
ongoing data. Update QC charts to form a graphic representation of continued
laboratory performance. Develop a statement of laboratory data quality for each
analyte by calculating the average percent recovery (R) and the standard deviation of
percent recovery (sr). Express the accuracy as a recovery interval from R - 2sr to
R + 2sr. For example, if R = 95% and sr = 5%, the accuracy is 85 to 105%.
13. QUALITATIVE IDENTIFICATION
13.1 Qualitative determination is accomplished by comparison of data from analysis of a sample or
blank with data from analysis of the calibration verification standard (Section 12.5).
13.2 PAH is identified in the sample by the presence of peaks and/or an elevated baseline (hump)
between the retention times of the naphthalene and indeno[l,2,3-ctf]pyrene peaks
(Section 11.3.3), as shown in Figure 1. The experience of the analyst shall weigh heavily in
interpretation of the chromatogram.
14. QUANTITA TIVE DETERMINA TION
14.1 Using the data system, compute the concentration of the PAH detected in the solution injected
into the HPLC (in /ig/mL) using the calibration factor (Section 7.4).
14.2 Concentration of PAH in oil: If neat oil was analyzed, the concentration of PAH in the oil is
determined using the following equation:
34
-------
Method 1654A
Equation 2
C (itglmL)
C (mg/g) = -!- -
" C. (mglmL)
where:
Co = Concentration of PAH in the oil sample
Cp = Concentration of PAH measured (from Sections 11.4 and 14.1)
C; = Concentration of oil in the solution injected into the HPLC
(from Sections 10.3.2, 11.4, and 14.1)
14.3 Concentration of diesel oil in QC extracts from Method 1662: Calculate the concentration of
diesel oil in QC extracts from Method 1662 by integrating the area per Section 7.6.1 and using
the calibration from Section 7.6.2 of this method, taking into account the dilution of these
extracts (Section 10.2).
14.4 Concentration of PAH in oil from Method 1662: The PAH content of oil is complicated by
the splitting and possible dilution of these extracts.
14.4.1 Concentration in undiluted extracts: This concentration is determined by Equation 3:
Equation 3
V xC 5 x 1 x C
_ e P - P_
0 [1/SxWJ Wr
where:
Co = Concentration of PAH in the oil sample
V, = Amount of extract split for HPLC analysis, in mL (1.0 mL)
Cp = Concentration of PAH measured
Wr = Weight of oil in the concentration tube in Method 1662
(Section 11.5.5 of Method 1662)
1/5 = Fraction of this weight used for the PAH determination
14.4.2 Concentration in diluted extracts: If the extract was diluted by a factor of 10
(Section 10.3 or 11.4), the concentration determined in Section 14.4.1 is multiplied
by 10.
14.5 If the concentration is to be expressed as weight percent, C0 is multiplied by 0.1.
14.6 Report results to three significant figures without correction for recovery.
15. METHOD PERFORMANCE
This method was validated in a single laboratory (Reference 6) using samples of hot-rolled drilling
mud (Reference 7).
-------
Method 1654A
References
1. "Carcinogens—Working With Carcinogens." Department of Health, Education, and Welfare,
Public Health Service, Centers for Disease Control [available through National Technical
Information System, 5285 Port Royal Road, Springfield, VA 22161, document no. PB-
277256]: August 1977.
2. "OSHA Safety and Health Standards, General Industry [29 CFR 1910], Revised."
Occupational Safety and Health Administration, OSHA 2206. Washington, DC: January 1976.
3. "Safety in Academic Chemistry Laboratories (3rd Edition)." American Chemical Society
Publication, Committee on Chemical Safety. Washington, DC: 1979.
4. "Handbook of Analytical Quality Control in Water and Wastewater Laboratories." USEPA,
EMSL-Ci, EPA-600/4-79-019. Cincinnati, OH: March 1979.
5. "Standard Practice for Sampling Water," ASTM Annual Book of Standards, Part 31, D3370-
76, ASTM. Philadelphia, PA: 1980.
6. "Determination of Polynuclear Aromatic Hydrocarbons and Diesel by Modified EPA Method
8310." Prepared for the American Petroleum Institute c/o Shell Development Co, Westhollow
Research Center, 3333 Highway 6 South, Houston, TX 77082 by Analytical Technologies
Inc., 225 Commerce Drive, Fort Collins, CO 80524: March 29 1991, April 12, 1991, and
August 18, 1992.
7. "Results of the API Study of Extraction and Analysis Procedures for the Determination of
Diesel Oil in Drilling Muds (Final Report)." American Petroleum Institute, Offshore Effluent
Guidelines Steering Committee, Technology Work Group, Prepared by J.C. Raia, Shell
Development Co. Houston, TX: April 18, 1991.
36
-------
Method 1654A
Table 1. Performance Data and Method Acceptance Criteria for PAH
PAH in
Diesel Oil1
100
7.6
Diesel Oil in Mud
Extract2
Phenanthrene
0.1
0.39-0.61
Criterion Units
Minimum level3 /yg/mL
Method Detection Limit4 //g/mg
Initial prec and recov
Precision (std dev)
PAH in diesel oil6 mg/mL 120
Diesel in mud extract6 mg/mL -- 0.55
Recovery
PAH in diesel oil5 mg/mL 1090-1340
Diesel in mud extract6 mg/mL -- 0.84-1.95
Calibration verification7 fjg/mL
Ongoing prec and recov
PAH in diesel oil6 mg/mL 1010-1450
Diesel in mud extract mg/mL -- 0.76-2.15
Matrix spike recovery6 pet -- 0.43-2.39
Duplicates RPD 9.5 44
Notes:
1 CAS Registry number 68534-30-5; No. 2 diesel oil used for these tests
2 From Method 1662
3 This is a minimum level at which the analytical system shall give recognizable signals and
acceptable calibration points.
4 40 CFR Part 136, Appendix B; MDL is measured as PAH in oil
5 Test concentration of diesel oil = 1250 //g/mL
6 Test concentration in diluted extract = 1.25 mg/mL
7 Test concentration = 0.50//g/mL
Table 2. HPLC Calibration Data
Analyte
Naphthalene
Phenanthrene
IndenoM ,2,3-ceflpyrene
Diesel oil
Retention Time*
(minutes)
7.2
10.0
18.9
7.0-20.0
Calibration solution
concentration (ug/mL)
Low
0.1
Medium
5
0.5
0.5
1250
High
2.0
Column system: Two C18 columns (150 mm long by 4.6 mm i.d., 300 angstroms) connected in
series, preceded by one C1B guard column (30 mm long by 4.6 mm i.d., 300 angstroms).
Column temperature 30°C; solvent flow rate 1.5 mL/min; linear gradient from 50% water/
50% acetonitrile at injection to 100% acetonitrile in 10 minutes, hold at 100% acetonitrile for
15 minutes.
37
-------
Method 1654A
00
O>
O>
I
oo
r^
_
CO
Q.
CO
Three-Component Standard
03
CO
CD
0)
n
£
>,
Q.
f
CO
No. 2 Diesel Oil
0.00
0.50
1.00 1.50
x 10^ minutes
2.00
Figure 1. Liquid Chromatography of the Three-Component Standard and of No. 2
Diesel Oil
38
-------
Method 1662
Total Extractable Material in
Drilling Mud
by SDS Extraction and
Gravimetry
-------
Method 1662
Total Extractable Material in Drilling Mud
by SDS Extraction and Gravimetry
1. SCOPE AND A PPLICA TION
1.1 This method is designed to determine the oil content of drilling mud by Soxhlet/Dean-Stark
(SDS) extraction and gravimetric measurement. However, this is a method-defined
measurement that does not discriminate oil from other materials capable of being extracted
from the mud. EPA Methods 1651, 1654, and 1663 can be used to aid in determining the
presence and identity of oil.
1.2 This method is for use in the Environmental Protection Agency's (EPA's) survey and
monitoring programs under the Federal Water Pollution Control Act.
1.3 The detection limit of this method is usually dependent on the level of background materials in
the drilling mud rather than instrumental limitations. The level in Table 1 typifies the
minimum level that can be detected with no interferences present.
1.4 Any modification of this method beyond those expressly permitted shall be considered a major
modification subject to application and approval of alternative test procedures under
40 CFR 136.4 and 136.5.
1.5 Each analyst that uses this method must demonstrate the ability to generate acceptable results
using the procedure in Section 8.2.
2. SUMMARY OF METHOD
2.1 Approximately 25 g of drilling mud is extracted with toluene in an SDS extractor
(Reference 1). The extract is evaporated to dryness using a rotary evaporator and nitrogen
blowdown apparatus. The weight of oil is determined using an analytical balance.
2.2 Quality is assured through reproducible calibration and testing of the extraction and
gravimetric systems.
3. INTERFERENCES
3.1 Solvents, reagents, glassware, and other sample processing hardware may lead to discrete
artifacts and elevated measurements causing misinterpretation of results.
3.2 All materials used in the analysis shall be demonstrated to be free from interferences by
running method blanks initially and with each sample batch (samples started through the
extraction process at the same time, to a maximum of ten). Specific selection of reagents and
purification of solvents by distillation in all-glass systems may be required.
3.3 Glassware and, where possible, reagents are cleaned by solvent rinse and/or baking at 200°C
for a minimum of 1 hour.
41
-------
Method 1662
4. SAFETY
4.1 The toxicity or carcinogenicity of each reagent used in this method has not been precisely
defined; however, each chemical should be treated as a potential health hazard. Exposure to
these chemicals must be reduced to the lowest possible level.
4.2 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 safety data sheets (MSDSs) should be made available to all personnel involved in the
chemical analysis. Additional information on laboratory safety can be found in References 2
through 4.
4.3 Methylene chloride has been classified as a known health hazard. All steps in this method
which involve exposure to this compound shall be performed in an OSHA-approved fume
hood.
5. APPARA TUS AND MA TERIALS
NOTE: Brand names, suppliers, and part numbers are for illustrative purposes only.
No endorsement is implied. Equivalent performance may be achieved using apparatus
and materials other than those specified here, but demonstration of equivalent
performance meeting the requirements of this method is the responsibility of the
laboratory.
5.1 Sampling equipment for discrete sampling.
5.1.1 Sample bottle: Wide-mouth amber glass or opaque cosmetic jars, 100-mL minimum,
with screw-cap. If amber bottles are not available, samples shall be protected from
light.
5.1.2 Bottle caps: Threaded to fit sample bottles. Caps shall be lined with PTFE or
aluminum.
5.1.3 Cleaning.
5.1.3.1 Bottles: Detergent water wash, tap water rinse, cap with aluminum foil,
and bake at 110 to 200°C for a minimum of 1 hour prior to use.
5.1.3.2 Liners: Detergent wash, tap water and solvent rinse, and bake at 110 to
200°C for a minimum of 1 hour prior to use.
5.1.4 Bottles and liners must be lot-certified to be free of artifacts by running blanks
according to this method. If blanks from bottles and/or liners without cleaning or
with fewer cleaning steps than required above show no detectable materials (per
Section 8.5), the bottle and liner cleaning steps that do not eliminate these artifacts
may be omitted.
5.2 Equipment for glassware cleaning.
5.2.1 Laboratory sink with overhead fume hood.
5.2.2 Oven: Capable of reaching 200°C within 2 hours and holding 200°C within ± 10°C.
42
-------
Method 1662
5.3 Equipment for sample preparation.
5.3.1 Laboratory fume hood.
5.3.2 Balances.
5.3.2.1 Analytical: Capable of weighing 1.0 mg.
5.3.2.2 Top loading: Capable of weighing 100 mg.
5.3.3 Beaker: 400- to 500-mL.
5.3.4 Spatula: Stainless steel.
5.3.5 Desiccator: Cabinet- or jar-type, capable of keeping the Kuderna-Danish concentrator
tubes (Section 5.5.1.1) dry during cooling.
5.4 Soxhlet/Dean-Stark (SDS) extractor.
5.4.1 Soxhlet: 50 mm i.d., 200-mL capacity with 500-mL flask (Cal-Glass LG-6900, or
equivalent, except substitute 500-mL round-bottom flask for 300-mL flat-bottom
flask).
5.4.2 Thimble: 123 mm long by 43 mm i.d. to fit Soxhlet (Cal-Glass LG-6901-122, or
equivalent).
5.4.3 Moisture trap: Dean-Stark or Barret with PTFE stopcock to fit Soxhlet (Figure 1).
5.4.4 Heating mantle: Hemispherical, to fit 500-mL round-bottom flask (Cal-Glass
LG-8801-112, or equivalent).
5.4.5 Variable transformer: Powerstat (Cal-Glass LG-8965-100, or equivalent).
5.5 Concentration apparatus.
5.5.1 Rotary evaporator or other concentration device capable of evaporating toluene: Any
concentration technique may be used provided that the requirements of Section 8.2
and the method detection limit in Table 1 are met.
5.5.2 Rotary evaporator with vacuum pump.
5.5.1.1 Rotary evaporator: Operated at approximately 60 rpm with built-in water
bath operated at approximately 90°C and condenser with tap water
approximately 45°C (Buchi Model Re-121, or equivalent).
5.5.1.2 Vacuum pump: CAST Model 1HAP-25-M100X (or equivalent).
5.5.2 Nitrogen blowdown apparatus: Equipped with water bath controlled at 40 to 50°C
(N-Evap, Organomation Associates, Inc., or equivalent), installed in a fume hood.
5.5.2.1 Concentrator tube: 10-to 15-mL, graduated (Kontes K-570050-1025, or
equivalent) with calibration verified.
5.5.3 Pipettes.
5.5.3.1 Disposable, Pasteur, 150 mm long by 5 mm i.d. (Fisher Scientific
13-678-6A, or equivalent).
5.5.3.2 Disposable, serological, 10-mL (6 mm i.d.).
5.6 Calculator or computer: Capable of calculating and maintaining statistics on initial
(Section 8.2) and ongoing (Section 11.3.4) performance.
43
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Method 1662
6. REAGENTS
6.1 Reference matrix: Blank drilling mud, playground sand, or similar material in which the
compounds of interest and interfering compounds are not detected by this method. May be
prepared by pre-extraction with methylene chloride and drying at 110 to 200°C for a minimum
of 4 hours.
6.2 Solvent: Toluene and methylene chloride, distilled in glass (Burdick and Jackson, or
equivalent).
6.3 White quartz sand, 60/70 mesh: For Soxhlet/Dean-Stark extraction, (Aldrich Chemical Co,
Cat No. 27,437-9, or equivalent).
6.4 Standard for diesel oil: Ideally, the oil standard used in this method should be from the oil
used on the drilling rig from which the mud sample is to be taken. If this oil is not available,
No. 2 diesel oil may be substituted. When not being used, the standard is stored in the dark at
-20 to -10°C in a screw-capped vial with PTFE-lined lid. A mark is placed on the vial at the
level of the solution so that solvent loss by evaporation can be detected. The vial is brought to
room temperature prior to use and solvent is added (if required).
6.5 Stock solution.
6.5.1 Diesel oil in toluene: Weigh 6.25 g of diesel oil to three significant figures in a 100-
mL ground-glass stoppered volumetric flask and fill to the mark with toluene. After
the oil is completely dissolved, transfer the solution to a clean 150-mL bottle with
PTFE-lined cap.
6.5.2 The stock solution should be checked for signs of degradation prior to the preparation
of the precision and recovery standard.
6.6 Precision and recovery standard: The stock solution is spiked into the reference matrix
(Section 6.1) for the determination of initial precision and recovery (IPR; Section 8.2) and
ongoing precision and recovery (OPR; Section 11.2). When 1 mL of this solution is spiked
into a 25-g reference matrix sample, a concentration of 0.25% (2.5 g/kg) will be produced.
7. CALIBRA TION
7.1 Verify calibration of the balance at 10 mg and 100 mg using class "S" weights.
7.2 Calibration shall be within + 10% (1 mg) at 10 mg and +2% (2 mg) at 100 mg. If not within
these limits, recalibrate the balance and repeat the test.
8. QUALITY ASSURANCE/QUALITY CONTROL
8.1 Each laboratory that uses this method is required to operate a formal quality assurance
program (Reference 5). The minimum requirements of this program consist of an initial
demonstration of laboratory capability, an ongoing analysis of standards and blanks as a test of
continued performance, analyses of spiked samples to assess accuracy, and analysis of
duplicates to assess precision. Laboratory performance is compared to established
performance criteria to determine if the results of analyses meet the performance
characteristics of the method.
44
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Method 1662
8.1.1 The analyst shall make an initial demonstration of the ability to generate acceptable
accuracy and precision with this method. This ability is established as described in
Section 8.2.
8.1.2 The analyst is permitted to modify this method to improve separations or lower the
costs of measurements, provided all performance requirements are met. Such
modifications may use alternative extraction or concentration techniques or alternative
HPLC columns. Each time a modification is made to the method, the analyst is
required to repeat the procedure in Section 8.2 to demonstrate method performance.
8.1.3 Analyses of spiked samples are required to demonstrate method accuracy. The
procedure and QC criteria for spiking are described in Section 8.3.
8.1.4 Analyses of duplicate samples are required to demonstrate method precision. The
procedure and QC criteria for duplicates are described in Section 8.4.
8.1.5 Analyses of blanks are required to demonstrate freedom from contamination. The
procedures and criteria for analysis of a blank are described in Section 8.5.
8.1.6 The laboratory shall, on an ongoing basis, demonstrate through calibration verification
and analysis of the OPR sample that the analysis system is in control. These
procedures are described in Section 11.
8.1.7 The laboratory shall maintain records to define the quality of data that is generated.
Development of accuracy statements is described in Sections 8.3.4 and 11.2.4.
8.2 Initial precision and accuracy (IPR): To establish the ability to generate acceptable precision
and accuracy, the analyst shall perform the following operations.
8.2.1 Extract and evaporate four samples of the precision and recovery standard
(Section 6.6) according to the procedure beginning in Section 10.
8.2.2 Using results of the set of four analyses, compute the average recovery (X) in g/kg
and the standard deviation of the recovery (s) in g/kg for each sample.
8.2.3 For each compound, compare s and X with the corresponding limits for initial
precision and accuracy in Table 1. If s and X meet the acceptance criteria, system
performance is acceptable and analysis of samples may begin. If, however, s exceeds
the precision limit or X falls outside the range for accuracy, system performance is
unacceptable. In this event, review this method, correct the problem, and repeat the
test.
8.3 Method accuracy: The laboratory shall spike a minimum of 10% (one sample in each set of
ten samples) of all drilling mud samples. This sample shall be spiked with the diesel oil that
was added to the drilling fluid. If a reference standard of diesel oil that was added to the
drilling fluid is not available, No. 2 diesel oil shall be used for this spike. If doubt of the
concentration of diesel oil in any of the remaining 90% of the samples exists, that sample shall
be spiked to confirm the diesel oil concentration.
8.3.1 The concentration of the spike in the sample shall be determined as follows.
8.3.1.1 If, as in compliance monitoring, the concentration of the oil in the sample
is being checked against a regulatory concentration limit, the spike shall be
at that limit or at 1 to 5 times higher than the background concentration
determined in Section 8.3.2, whichever concentration is higher.
45
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Method 1662
8.3.1.2 If the concentration of the oil in a sample is not being checked against a
limit, the spike shall be at the concentration of the precision and recovery
standard (Section 6.6) or at 1 to 5 times higher than the background
concentration, whichever concentration is higher.
8.3.2 Analyze one sample aliquot to determine the background concentration (B) of oil. If
necessary, prepare a standard solution appropriate to produce a level in the sample at
the regulatory concentration limit or at 1 to 5 times the background concentration (per
Section 8.3.1). Spike a second sample aliquot with the standard solution and analyze
it to determine the concentration after spiking (A) of each analyte. Calculate the
percent recovery (P) of the oil using Equation 1:
Equation 1
p = 100 (A-B)
f
where'.
A = Concentration of analyte after spiking
B = Background concentration of oil
T = True value of the spike
8.3.3 Compare the percent recovery for total oil with the corresponding QC acceptance
criteria in Table 1. If the results of the spike fail the acceptance criteria, and the
recovery of the QC standard in the ongoing precision and recovery test (Sections
10.1.3 and 11.2.4) is within the acceptance criteria in Table 1, an interference may be
present. (See Section 3 for identification of interferences). In this case, the result
may not be reported for regulatory compliance purposes. If, however, the results of
both the spike and the ongoing precision and recovery test fail the acceptance criteria,
me analytical system is judged to be out of control, and the problem shall be
identified and corrected and the sample batch reanalyzed.
8.3.4 As part of the QA program for the laboratory, method accuracy for samples shall be
assessed and records shall be maintained. After the analysis of five spiked samples
in which the recovery passes the test in Section 8.3, compute the average percent
recovery (P) and the standard deviation of the percent recovery (sp). Express the
accuracy assessment as a percent recovery interval from P 2sp to P + 2sp. For
example, if P = 90% and sp = 10% for five analyses of diesel oil, the accuracy
interval is expressed as 70 to 110%. Update the accuracy assessment on a regular
basis (e.g., after each five to ten new accuracy measurements).
8.4 The laboratory shall analyze duplicate samples for each drilling-mud type at a minimum of
10% (one sample for each ten sample set). A duplicate sample shall consist of a well-mixed,
representative aliquot of the sample.
8.4.1 Analyze one sample in the set in duplicate per the procedure beginning in Section 10.
8.4.2 Compute the relative percent difference (RPD) between the two results per the
following equation:
46
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Method 1662
Equation 2
RPD = I ' d_ x 100
(D, + Z>2)/2
where:
£>, = Concentration of diesel in the sample
D2 = Concentration of diesel oil in the second (duplicate) sample
8.4.3 The relative percent difference for duplicates shall meet the acceptance criteria in
Table 1. If the criteria are not met, the analytical system is be judged to be out of
control, and the problem must be immediately identified and corrected and the sample
set reanalyzed.
8.5 Blanks: Reference matrix blanks (Section 6.1) are analyzed to demonstrate freedom from
contamination.
8.5.1 Extract and concentrate a 25-g aliquot of the reference matrix initially and with each
sample batch (samples started through the analysis at the same time, to a maximum of
ten samples).
8.5.2 If greater than 0.2 g/kg of material is detected in a blank, analysis of samples is
halted until the source of contamination is eliminated and a blank shows no evidence
of contamination.
8.6 The specifications contained in this method can be met if the apparatus used is calibrated
properly, then maintained in a calibrated state. The standards used for initial precision and
recovery (IPR, Section 8.2) and ongoing precision and recovery (OPR, Section 11.2) should
be identical, so that the most precise results will be obtained.
8.7 Depending on specific program requirements, field replicates and field spikes of diesel oil into
samples may be required to assess the precision and accuracy of the sampling and sample
transporting techniques.
9. SAMPLE COLLECTION, PRESERVATION, AND HANDLING
9.1 Collect drilling mud samples in wide-mouth glass containers following conventional sampling
practices (Reference 6).
9.2 Samples must be representative of the entire bulk drilling mud. In some instances, composite
samples may be required.
9.3 Maintain samples in the dark at 0 to 4°C from the time of collection until analysis.
9.4 Analyze samples within 28 days of collection.
10. SAMPLE EXTRACTION AND CONCENTRATION
10.1 Preparation of sample and QC aliquots.
10.1.1 Transfer approximately 25 g of a well-homogenized and representative portion of the
drilling mud to a tared 400- to 500-mL beaker. Determine and record the weight.
47
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Method 1662
10.1.2 Add approximately 50 g of quartz sand (Section 6.3) to the beaker and mix the
drilling mud and sand thoroughly.
10.1.3 QC standard and blank: Used for tests of initial (Section 8.2) and ongoing
(Section 11.2) precision and accuracy. For each of the four initial precision and
recovery (IPR) standards, the ongoing precision and recovery (OPR) standard, and the
blank (Section 8.5), prepare aliquots as follows.
10.1.3.1 Place approximately 25 g of the reference matrix (Section 6.1) in a clean
400- to 500-mL beaker.
10.1.3.2 Spike 1 mL of the precision and recovery standard (Section 6.6) into the
IPR or OPR standard. Do not spike the blank.
10.1.3.3 Add approximately 50 g of quartz sand (Section 6.3) to the beaker and mix
thoroughly.
10.2 Soxhlet/Dean-Stark extraction.
10.2.1 Pre-extraction: Used to clean the SDS extractor. Pre-extraction may be eliminated if
extractable material is not found in blanks.
10.2.1.1 Charge a clean extraction thimble with 50 g of quartz sand (Section 6.3).
Do not disturb the silica layer throughout the extraction process.
10.2.1.2 Place the thimble in a clean extractor. Place 30 to 40 mL of toluene in the
receiver and 200 to 250 mL in the flask.
10.2.1.3 Begin the extraction by heating the flask until the toluene is boiling. When
properly adjusted, one to two drops of toluene per second will fall from
the condenser tip into the receiver. Pre-extract the apparatus for a
minimum of 4 hours.
10.2.1.4 After pre-extraction, cool and disassemble the apparatus. Rinse with
methylene chloride and allow to air-dry in a hood.
10.2.2 SDS extraction.
10.2.2.1 Load the sample (from Section 10.1.2) and QC aliquot(s) and blank (from
Section 10.1.3.3) into pre-cleaned thimbles.
10.2.2.2 Reassemble the apparatus and add a fresh charge of toluene to the
receivers and reflux flasks. Rinse the beakers into their respective
thimbles using 10 to 20 mL of toluene.
10.2.2.3 Apply power to the heating mantle to begin refluxing. Adjust the reflux
rate to match the rate of percolation through the sand bed until sufficient
water has been removed so that the flow of toluene is no longer restricted.
10.2.2.4 Drain the water from the receiver at 1 to 2 hours and 8 to 9 hours, or
sooner if the receiver fills with water. Record the total volume of water
collected. Reflux the sample for a total of 16 to 24 hours. Cool to room
temperature.
10.2.2.5 Estimate and record the volume of extract (to the nearest 100 mL).
48
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Method 1662
10.3 Concentration.
10.3.1 Add one or two clean boiling chips to the evaporative flask and attach it to the rotary
evaporator.
10.3.1.1 Place the round-bottom flask in the hot-water bath (approximately 90°C)
so that approximately one-half of the flask is immersed in hot water.
10.3.1.2 Start the flow of cooling water and turn on the vacuum pump. Rotate the
flask slowly at first to control the rate of evaporation of the toluene.
10.3.1.3 When the apparent volume reaches a few milliliters, remove the flask from
the hot water bath and allow it to cool for at least 10 minutes. To
minimize the loss of the more volatile components of oil, do not take the
sample to dryness in the rotary evaporator.
10.3.1.4 Turn off the pump and cooling water.
10.3.1.5 Disassemble the apparatus.
10.3.1.6 Using a squeeze bottle or pipette, rinse the inside surface of the round-
bottom flask with a small portion of acetonitrile. Transfer the solution to a
calibrated Kuderna-Danish concentrator tube. Repeat the rinsing and
transfer two more times to quantitatively transfer the solution to the
concentrator tube.
10.4 Extract for other analyses: If a portion of the extract is to be retained for HPLC analysis
using Method 1654A or GC/FID analysis using Method 1663, the extract is split as follows.
10.4.1 Adjust the extract volume to 5.0 mL with acetonitrile.
10.4.2 Remove 1.00 mL with a volumetric pipette and place in a 2- to 3-mL amber vial with
PTFE-lined screw-cap. Mark a line on the vial at the level of the solution. Seal and
store in the dark at -20 to -10°C.
10.4.3 Evaporate the remaining 4 mL of extract per the steps below.
10.5 Evaporation to dryness.
10.5.1 Place the receiver in the water in the nitrogen blowdown apparatus. Adjust the water
temperature to 40 to 50°C.
10.5.2 Adjust the height of the blowdown needle to approximately 1 cm above the surface of
the solution.
10.5.3 Adjust the nitrogen flow rate so that it is sufficient to create a depression in the
surface of the solution but not so great that the solution spatters.
10.5.4 Evaporate the solvent until the volume is constant, but no longer than 30 minutes.
Wipe the outside surface of the concentrator tube dry and cool the tube in the
desiccator.
10.5.5 Weigh the receiver. If doubt exists that constant weight has been achieved, return the
receiver to the blowdown apparatus and evaporate solvent for 15 minutes more. Cool
the receiver in the desiccator and weigh the receiver. Constant weight is achieved
when the readings differ by less than 5% or 5 mg, whichever is greater.
49
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Method 1662
71. SYSTEM AND LABORA TORY PERFORMANCE
11.1 Calibration verification: Verify calibration of the balance per Section 7 before and after each
set of 12 or fewer measurements. (The 12 measurements will normally be ten samples, plus
one ongoing precision and recovery standard, plus one blank.) If calibration is not verified
after the measurements, recalibrate the balance and reweigh the batch.
11.2 Ongoing precision and recovery.
11.2.1 Weigh the evaporated precision and recovery standard extracted and concentrated with
each batch of samples.
11.2.2 Calculate the concentration of oil in this standard.
11.2.3 Compare the concentration with the limits for ongoing precision and recovery in
Table 1. If the concentration is in the range specified, the extraction and evaporation
processes are in control and analysis of blanks and samples may proceed. If,
however, the concentration is not in the specified range, these processes are not in
control. In this event, correct the problem, re-extract the sample batch, and repeat
the ongoing precision and recovery test.
11.2.4 Add results that pass the specification in Section 11.2.3 to initial and previous ongoing
data. Update QC charts to form a graphic representation of continued laboratory
performance. Develop a statement of laboratory data quality for each analyte by
calculating the average percent recovery (R) and the standard deviation of percent
recovery (sr). Express the accuracy as a recovery interval from R 2sr to R + 2sr.
For example, if R = 95% and sr = 5%, the accuracy is 85 to 105%.
12. QUANTITATIVE DETERMINATION
12.1 Determination of dry weight of sample and of percent solids.
12.1.1 Using the sample weight (Section 10.1.1) and the weight (volume) of water in the
moisture trap (Section 10.2.4.4), calculate the dry weight of solids in the sample as
follows:
Equation 3
w=w-w
d s w
where:
Wd = Dry weight of solids, in grams
Ws = Weight of sample, in grams
Ww = Weight of water, in grams
50
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Method 1662
12.1.2 Calculate the percent solids as follows:
Equation 4
W.
% solids = 100 -J.
^
where:
Wd = Dry weight of solids, in grams
Ws = Weight of sample, in grams
12.2 Determination of extractable material concentration.
12.2.1 Calculate the concentration of extractable material in the total (wet) sample using the
following equation:
Equation 5
W
Concentration (%) = 0.1 —
Ws
where:
Wr = Weight of extractable material in receiver, in mg
Ws = Weight of sample, in grams
12.2.2 If 1 mL of the 5-mL extract was removed for HPLC or GC analysis, multiply the
result by 1.25 to compensate for this loss.
12.3 Report results to two significant figures without correction for recovery.
13. METHOD PERFORMANCE
This method was validated in a single laboratory (Reference 7) using samples of hot-rolled drilling
mud (Reference 8).
51
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Method 1662
References
1. Lamparski, L.L. and T.J. Nestrick. "Novel Extraction Device for the Determination of
Chlorinated Dibenzo-p-dioxins (PCDDs) and Dibenzofurans (PCDFs) in Matrices Containing
Water." Chemosphere, 19: 27-31, 1989.
2. "Carcinogens—Working With Carcinogens." Department of Health, Education, and Welfare,
Public Health Service, Centers for Disease Control [available through National Technical
Information System, 5285 Port Royal Road, Springfield, VA 22161, document no. PB-
277256]: August 1977.
3. "OSHA Safety and Health Standards, General Industry [29 CFR 1910], Revised."
Occupational Safety and Health Administration, OSHA 2206. Washington, DC: January 1976.
4. "Safety in Academic Chemistry Laboratories (3rd Edition)." American Chemical Society
Publication. Committee on Chemical Safety. Washington, DC: 1979.
5. "Handbook of Analytical Quality Control in Water and Wastewater Laboratories." USEPA,
EMSL-Ci, EPA-600/4-79-019. Cincinnati, OH: March 1979.
6. "Standard Practice for Sampling Water," ASTM Annual Book of Standards, Part 31, D3370-
76, ASTM, Philadelphia, PA: 1980.
7 "Results of the API Study of Extraction and Analysis Procedures for the Determination of
Diesel Oil in Drilling Muds (Final Report)." American Petroleum Institute, Offshore Effluent
Guidelines Steering Committee, Technology Work Group, Prepared by J.C. Raia, Shell
Development Co. Houston, TX: April 18, 1991.
8. "Development of Specifications for Method 1662." Analytical Technologies, Inc., Work
Order 92-06-025, prepared for the American Petroleum Institute. 1220 L St NW, Washington,
DC: August 18, 1992.
52
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Method 1662
Table 1. Method Acceptance Criteria for Diesel Oil1 in Drilling Mud
Diesel OH
Acceptance Criterion
Method Detection Limit (matrix)3
Initial precision and recovery4
Precision [standard deviation]
Recovery [mean; X]
Ongoing precision and recovery4
Matrix spike recovery
Precision of duplicates
Notes:
Section
8.2.3
11.2.3
8.3.3
8.4.3
Units2
g/kg
g/kg
g/kg
g/kg
percent
RPD
Amount
1.1
0.85
1.18 -3.73
1.08 -3.83
35 159
34
1 CAS Registry number 68534-30-5
2 To convert to weight percent, multiply the amount by 0.1
3 40 CFR Part 136, Appendix B; measured in API Mud number 101-1
4 Text concentration: 2.5 g/kg (0.25 percent) diesel oil in mud
5 Precision of duplicate analyses must be <34%.
53
-------
Method 1662
AS2-010-002
Figure 1. Soxhlet/Dean-Stark Extractor
54
-------
Method 1663
Differentiation of Diesel and
Crude Oil by GC/FID
-------
Method 1663
Differentiation of Diesel and Crude Oil by GC/FID
1. SCOPE AND APPLICA TION
1.1 This method differentiates between diesel oil and crude oil in drilling muds and other sources
by comparing the ratio of n-alkanes in the Cg-C^ range as determined by gas chromatography
(GC) with a flame-ionization detector (FID).
1.2 This method is for use in the Environmental Protection Agency's survey programs and may be
used for compliance monitoring as part of the "Effluent Limitations Guidelines and New
Source Performance Standards for the Offshore Subcategory of the Oil and Gas Extraction
Point Source Category" [50 FR 34592].
1.3 For oil in drilling muds, this method is designed to be used in conjunction with the extraction
procedure in EPA Method 1662.
1.4 This method cannot differentiate between mineral oil and diesel/crude oil. EPA
Method 1654A can be used to determine that the oil is not mineral oil by measurement of the
polynuclear aromatic (PAH) content.
1.5 When used in conjunction with EPA Method 1662, the estimated detection limit for diesel or
crude oil in drilling mud is 100 mg/kg, excluding interferences caused by other materials in
the mud.
1.6 Any modification of this method beyond those expressly permitted shall be considered as a
major modification subject to application and approval of alternative test procedures under
40 CFR 136.4 and 136.5.
1.7 The gas chromatography portions of this method are restricted to use by or under the
supervision of analysts experienced in the use of gas chromatography and in the interpretation
of gas chromatograms. Each laboratory that uses this method must generate acceptable results
using the procedures described in Sections 7.1, 8.2, and 12 of this method.
2. SUMMARY OF METHOD
2.1 An oil sample is diluted in hexane. An internal standard is added and an aliquot is injected
into a gas chromatograph (GC). The components of the oil are separated by the GC and
detected by a flame-ionization detector (FID).
2.2 Identification of diesel oil or crude oil (qualitative analysis) is performed by comparing ratios
of groups of n-alkanes.
2.3 Quantitative analysis is performed by calibrating the GC/FID with hexadecane using an
internal standard technique. The calibration factor is then used to determine the amounts of
the groups of n-alkanes. A quotient of these amounts establishes that the oil is diesel or crude.
2.4 Quality is assured through reproducible calibration and testing of the extraction and GC
systems.
57
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Method 1663
3. CONTAMINATION AND INTERFERENCES
3.1 Solvents, reagents, glassware, and other sample processing hardware may yield artifacts and/or
elevated baselines causing misinterpretation of chromatograms.
3.1.1 All materials used in the analysis shall be demonstrated to be free from interferences
by running method blanks initially and with a sample batch (samples started through
the extraction process at the same time, to a maximum of ten). Specific selection of
reagents and purification of solvents by distillation in all-glass systems may be
required.
3.1.2 Glassware and, where possible, reagents are cleaned by rinsing with solvent or baking
at 450°C for a minimum of I hour.
3.2 Interferences co-extracted from samples may vary from source to source, depending on the
diversity of the site being sampled.
4. SAFETY
4.1 The toxicity or carcinogenicity of each reagent used in this method has not been defined.
Therefore, 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.
4.2 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 safety data sheets (MSDSs) should also be made available to all personnel involved in
the chemical analysis. Additional references to laboratory safety can be found in References I
through 3.
5. A PPA RA TUS A ND MA TERIA L S
NOTE: Brand names, suppliers, and pan numbers are for illustrative purposes only.
No endorsement is implied. Equivalent performance may be achieved using apparatus
and materials other than those specified here, but demonstration of equivalent
performance meeting the requirements of this method is the responsibility of the
laboratory.
5.1 Equipment for glassware cleaning.
5.1.1 Laboratory sink with overhead fume hood.
5.1.2 Kiln: Capable of reaching 450°C within 2 hours and holding 450°C within ± 10°C,
with temperature controller and safety switch (Cress Manufacturing Co., Santa Fe
Springs, CA, B31H or X31TS, or equivalent).
5.2 Equipment for sample preparation.
5.2.1 Laboratory fume hood.
5.2.2 Analytical balance: Capable of weighing O.I mg.
5.2.3 Glassware.
58
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Method 1663
5.2.3.1 Disposable pipettes: Pasteur, 150 mm long by 5 mm i.d. (Fisher Scientific
13-678-6A, or equivalent).
5.2.3.2 Glass pipettes: 0.1-, 1.0-, and 10-mL, accurate to 1% or better.
5.2.3.3 Volumetric flasks: Glass, 10- and 100-mL.
5.2.3.4 Sample vials: Amber glass, 1- to 3-mL with PTFE-lined screw- or crimp-
cap, to fit GC autosampler.
5.3 Gas Chromatograph (GC): Analytical system with split injection, capillary column,
temperature program with initial and final isothermal holds, and all required accessories,
including syringes, analytical columns, gases, detector, and recorder. The analytical system
shall meet the performance specifications in Section 12.
5.3.1 Column: 30 m long (+5 m) by 0.25 mm i.d. (±0.02 mm), 99% methyl, 1% vinyl,
1.0 pm film thickness, bonded-phase fused-silica capillary (Supelco SPB-1, or
equivalent).
5.3.2 Detector: Flame ionization. Capable of detecting 10 ng of hexadecane.
5.4 GC data system: Shall collect and record GC data, store GC runs in magnetic memory or on
magnetic disk or tape, process GC data, compute peak areas, store calibration data including
retention times and the response factor, identify GC peaks through retention times, and
compute concentrations.
5.4.1 Data acquisition: GC data shall be collected continuously throughout the analysis and
stored on a magnetic storage device.
5.4.2 Response factor: The data system shall be used to record and maintain the response
factor (Section 7). Computations of relative standard deviation (coefficient of vari-
ation; CV) are used for testing calibration linearity. Statistics on initial (Section 8.2)
and ongoing (Section 12.5) performance shall be computed and maintained.
5.4.3 Data processing: The data system shall search, locate, identify, and quantify the
compounds of interest in each GC analysis. Software routines shall be employed to
compute and record retention times and peak areas. Displays of chromatograms and
library comparisons are required to verify results.
6. REAGENTS
6.1 Hexane: ACS grade or equivalent.
6.2 Standards: Purchased as solutions or mixtures with certification as to their purity,
concentration, and authenticity, or prepared from materials of known purity and composition.
If compound purity is 96% or greater, the weight may be used without correction to compute
the concentration of the standard. If diesel oil in drilling mud is to be tested, the diesel oil
standard used in this method should be from the diesel oil added to the mud on the drilling rig
from which the mud sample is taken. If this oil is not available, No. 2 diesel oil from a local
source may be substituted.
6.2.1 Stock solutions: Prepare in hexane for injection into the GC. Observe the safety
precautions in Section 4.
-------
Method 1663
6.2.1.1 Diesel oil (62.5 mg/mL): If QC extracts from Method 1662 are to be
tested, use the oil that was spiked to produce these extracts. Weigh 6.25 g
of diesel oil to three significant figures in a 100-mL ground-glass stoppered
volumetric flask and fill to the mark with hexane. After the oil is
completely dissolved, transfer the solution to a 150-mL bottle with
PTFE-lined cap.
6.2.1.2 Normal hydrocarbons—decane (C,2), hexadecane (C16), and tetracosane
(C24): Dissolve an appropriate amount of reference material in a suitable
solvent. For example, weigh 10.0 mg of decane in a 10-mL volumetric
flask and fill to the mark with hexane. After the decane is completely
dissolved, transfer the solution to a 15-mL vial with PTFE-lined cap.
6.2.1.3 Internal standard: Dissolve 1.0 g of 1,3,5-trichlorobenzene (TCB, Kodak
No. 1801 or equivalent) in 100 mL hexane. After the TCB is completely
dissolved, transfer the solution to a 150-mL bottle with PTFE-lined cap.
Label with the concentration and date. Mark the level of the meniscus on
the bottle to detect solvent loss.
6.2.1.4 Stock solutions should be checked for signs of degradation prior to the
preparation of calibration or performance test standards.
6.2.2 Normal hydrocarbon calibration standards (CAL): Dilute and mix the stock solutions
(Section 6.2.1.2) in hexane to produce the calibration standards shown in Table 1.
The three solutions permit the response of hexadecane to be measured as a function of
concentration, and decane and tetracosane permit the retention-time window of diesel
oil to be defined. The medium-level solution is used for calibration verification.
6.2.3 Precision and recovery standard: Dilute the stock solution of diesel oil
(Section 6.2.1.1) to produce a concentration of 1.25 mg/mL in hexane. This standard
is used for initial precision and recovery (IPR, Section 8.2) and ongoing precision and
recovery (OPR, Section 12.5).
6.2.4 Addition of internal standard: Using a micropipette or microsyringe, transfer 100 /iL
of each standard solution (Section 6.2.2 or 6.2.3) to a GC injection vial. Add 100 pL
of the TCB internal standard (Section 6.2.1.3) to each vial and mix thoroughly.
Calibration and precision and recovery standards are made fresh daily to avoid solvent
loss by evaporation.
6.2.5 Stability of standards.
6.2.5.1 When not being used, standards are stored in the dark at -20 to -10°C in
screw-capped vials with PTFE-lined lids. A mark is placed on the vial at
the level of the solution so that solvent loss by evaporation can be
detected. The vial is brought to room temperature prior to use. Any
precipitate is redissolved and solvent is added if solvent loss has occurred.
6.2.5.2 Standard solutions used for quantitative purposes (Sections 6.2.1 through
6.2.3) shall be analyzed within 48 hours of preparation and on a monthly
basis thereafter for signs of degradation. Standards will remain acceptable
if the peak area remains within + 15% of the area obtained in the initial
analysis of the standard.
60
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Method 1663
7. CALIBRATION
7.1 Establish gas chromatographic operating conditions given in Table 2. Verify that the GC
meets the minimum level in Table 4. The gas chromatograph is calibrated using the internal
_ standard technique. _
NOTE: Because each GC is slightly different, it may be necessary to adjust the
operating conditions (carrier gas flow rate and column temperature and temperature
program) slightly until the retention times in Table 3 are met.
7.2 Internal standard calibration procedure: 1,3,5-Trichlorobenzene (TCB) has been shown to be
free of interferences from the diesel and crude oils tested in the development of this method.
Check for acceptability by injecting 0.5 /xL of the internal standard solution (Section 6.2.1.3)
into the GC\FID. If a major peak other than the TCB peak appears in the chromatogram,
interference with the peaks used for determination of diesel/crude oil may occur. In this case,
the analyst must choose an alternative internal standard that is free from interferences.
7.2.1 Inject 1 /zL of each calibration standard containing the internal standard (Table 1 and
Section 6.2.2) into the GC\FID. The TCB will elute approx 8.5 minutes after
injection. For the GC\FID used in the development of this method, the TCB internal
standard peak was 30 to 50% of full scale at an attenuator setting of 8 x 10"11 amp.
7.2.2 Response factor of hexadecane (C16).
7.2.2.1 Tabulate the peak areas against concentration for the TCB and C16 peaks.
Calculate response factors (RF) at each concentration for C16 using the
following equation:
Equation 1
RF (
where:
As = Area of the peak to be measured
Ch = Concentration of the internal standard, in pglkg
A^ = Area of the internal standard peak
C. = Concentration of the peak to be measured, in
7.2.2.2 Calculate the average, standard deviation, and relative standard deviation
(RSD) of the response factors. If the RF is constant (< 15% RSD) over
the calibration range, linearity through the origin can be assumed and
system performance is acceptable; if not, the system must be recalibrated.
7.2.2.3 The average response factor is verified on each working 8-hour shift by
measurement of the medium-level calibration standard (Section 12.4).
7.2.3 Single-point calibration for diesel oil: Inject the precision and recovery standard
(Section 6.2.3) to which the internal standard has been added (Section 6.2.4) to
produce a single calibration point for diesel oil.
61
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Method 1663
7.2.3.1 Integrate the area of the C16 peak.
7.2.3.2 Determine the response factor for diesel oil using Equation 1.
8. QUALITY ASSURANCE/QUALITY CONTROL
8.1 Each laboratory that uses this method is required to operate a formal quality assurance
program (Reference 4). The minimum requirements of this program consist of an initial
demonstration of laboratory capability, an ongoing analysis of standards and blanks as a test of
continued performance, analyses of spiked samples to assess accuracy, and analysis of
duplicates to assess precision. Laboratory performance is compared to established
performance criteria to determine if the results of analyses meet the performance
characteristics of the method. If the determination of diesel/crude oil is to be made on extracts
from Method 1662, the quality control samples for initial precision and recovery (IPR), spiked
samples, duplicates, and ongoing precision and recovery (OPR) from Method 1662 shall be
substituted for those in the QC tests below, and the specifications in Table 4 of this method for
extracts from Method 1662 shall be met.
8.1.1 The analyst shall make an initial demonstration of the ability to generate acceptable
accuracy and precision with this method. This ability is established as described in
Section 8.2.
8.1.2 The analyst is permitted to modify this method to improve separations or lower the
costs of measurements, provided all performance requirements are met. Each time a
modification is made to the method, the analyst is required to achieve the minimum
level (Section 7.1) and to repeat the procedure in Section 8.2 to demonstrate method
performance.
8.1.3 Analyses of spiked samples are required to demonstrate method accuracy when
extracts from Method 1662 are analyzed. The procedure and QC criteria for spiking
are described in Section 8.3.
8.1.4 Analyses of duplicate samples are required to demonstrate method precision when
extracts from Method 1662 are analyzed. The procedure and QC criteria for
duplicates are described in Section 8.4.
8.1.5 Analyses of blanks are required to demonstrate freedom from contamination. The
procedures and criteria for analysis of a blank are described in Section 8.5.
8.1.6 The laboratory shall, on an ongoing basis, demonstrate through calibration verification
and the analysis of the precision and recovery standard (Section 6.2.3) that the
analysis system is in control. These procedures are described in Section 12.
8.1.7 The laboratory shall maintain records to define the quality of data that is generated.
Development of accuracy statements is described in Sections 8.3.2 and 12.5.4.
8.2 Initial precision and accuracy: The initial precision and recovery test is performed using the
precision and recovery standard. If extracts from Method 1662 are to be analyzed, the
extracts from the initial precision and recovery test in that method shall be used; otherwise, the
laboratory shall generate acceptable precision and recovery by performing the following
operations.
-------
Method 1663
8.2.1 Using diesel oil, prepare four separate aliquots of the precision and recovery standard
(Section 6.2.3) using the procedure in Section 10. Add the internal standard to each
aliquot (Section 6.2.4). Analyze these aliquots using the procedure in Section 11.
8.2.2 Using results of the set of four analyses, compute the average recovery (X) in mg/mL
and the standard deviation of the recovery (s) in mg/mL for each sample by the
internal standard method (Sections 7.2 and 14.2).
8.2.3 For each compound, compare s and X with the corresponding limits for initial
precision and accuracy in Table 4. If s and X meet the acceptance criteria, system
performance is acceptable and analysis of samples may begin. If, however, s exceeds
the precision limit or X falls outside the range for accuracy, system performance is
unacceptable. In this event, review this method, correct the problem, and repeat the
test.
8.3 Method accuracy: If extracts from Method 1662 are to be analyzed, the extract from the
accuracy test in that method shall be used; otherwise, an accuracy test is unnecessary. The
procedure for determining method accuracy is given in Section 8.3 of Method 1662, and the
specification for accuracy is given in Table 4 of this method.
8.3.1 Compare the percent recovery for diesel oil with the corresponding QC acceptance
criteria in Table 4. If the results of the spike fail the acceptance criteria, and the
recovery of the QC standard in the ongoing precision and recovery test (Section
12.6.3) is within the acceptance criteria in Table 4, an interference may be present.
In this case, the result may not be reported for regulatory compliance purposes. If,
however, the results of both the spike and the ongoing precision and recovery test fail
the acceptance criteria, the analytical system is judged to be out of control, and the
problem must be immediately identified and corrected and the sample batch
reanalyzed.
8.3.2 As part of the QA program for the laboratory, method accuracy for samples shall be
assessed and records shall be maintained. After the analysis of five spiked samples
in which the recovery passes the test in Section 8.3.1, compute the average percent
recovery (P) and the standard deviation of the percent recovery (sp). Express the
accuracy assessment as a percent recovery interval from P 2sp to P + 2sp. For
example, if P = 90% and sp = 10% for five analyses of diesel oil, the accuracy
interval is expressed as 70 to 110%. Update the accuracy assessment on a regular
basis (e.g., after each five to ten new accuracy measurements).
8.4 Duplicates: If extracts from Method 1662 are to be analyzed, the extracts from the duplicates
test in that method shall be used. The procedure for preparing duplicates is given in Section
8.4 of Method 1662, and the specification for RPD is given in Table 4 of this method. If
extracts from Method 1662 are not to be analyzed, duplicates of the precision and recovery
standard (Section 6.2.3) are analyzed, and the specification for RPD is given for diesel oil in
Table 4 of this method.
8.4.1 Analyze each of the duplicates per the procedure in Section 11 and compute the
results per Section 14.
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Method 1663
8.4.2 Calculate the relative percent difference (RPD) between the two results per the
following equation:
Equation 2
RPD = ' ' " _ i_ x 100
vv/zere:
D, = Concentration of diesel oil in the sample
D2 = Concentration of diesel oil in the second (duplicate) sample
8.4.3 The relative percent difference for duplicates shall meet the acceptance criteria in
Table 4. If the criteria are not met, the analytical system shall be judged to be out of
control, and the problem must be immediately identified and corrected and the sample
batch reanalyzed.
8.5 Blanks: If extracts from Method 1662 are to be analyzed, the extracts from blanks in that
method shall be analyzed in addition to the blanks in this method.
8.5.1 Rinse the glassware used in preparation of the extracts in this method with hexane and
analyze a 1-^L aliquot of the rinsate using the procedure in Section 11. Compute the
results per Section 14.
8.5.2 If any peak is detected in a blank at greater than the minimum level in Table 1,
analysis of samples is halted until the source of contamination is eliminated and a
blank shows no evidence of contamination.
8.6 The specifications contained in this method can be met if the apparatus used is calibrated
properly, then maintained in a calibrated state. The standards used for initial precision and
recovery (IPR, Section 8.2) and ongoing precision and recovery (OPR, Section 12.5) precision
and recovery should be identical, so that the most precise results will be obtained. The GC
instrument will provide the most reproducible results if dedicated to the settings and conditions
required for the analyses given in this method.
8.7 Depending on specific program requirements, field replicates and field spikes of diesel oil into
samples may be required when Method 1662 and this method are used to assess the precision
and accuracy of the sampling and sample transporting techniques.
9. SAMPLE COLLECTION, PRESERVATION, AND HANDLING
9.1 Oil samples are collected in 20- to 40-mL vials with PTFE- or aluminum-foil-lined caps and
stored in the dark at -20 to -10°C.
9.2 If extracts from Method 1662 are to be analyzed, the laboratory should be aware that sample
and extract holding times for this method have not yet been established. However, based on
tests of wastewater for the analytes determined in this method, samples shall be extracted
within seven days of collection and extracts shall be analyzed within 40 days of extraction.
64
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Method 1663
9.3 As a precaution against analyte and solvent loss or degradation, sample extracts are stored in
glass bottles with PTFE-lined caps, in the dark, at -20 to -10°C.
10. DILUTION OF OIL AND EXTRACTS
10.1 Neat oil samples: If oil is received in neat form, it should be diluted to bring the
concentration within the range of the instrument. If the oil is No. 2 diesel oil, the appropriate
concentration will be approximately 1.25 mg/mL.
10.2 Extracts from Method 1662: If extracts of samples from Method 1662 are to be analyzed,
these extracts (from Section 10.4.2 of that method) are analyzed undiluted unless diesel oil is
known or suspected to be present.
10.3 Neat oil expected to be diesel oil.
10.3.1 Weigh 100 mg into a 10-mL volumetric flask and dilute to the mark with hexane to
produce a concentration of 10 mg/mL. Stopper and mix thoroughly.
10.3.2 Using a calibrated 1.0-mL volumetric pipette, withdraw 1.0-mL of the solution
created in Section 10.3.1.1 and place in a 10-mL volumetric flask. Then withdraw an
additional 0.25 mL of the solution and add it to the 10-mL volumetric flask (for a
total of 1.25 mL). Fill to the mark with hexane to produce a concentration of 1.25
mg/mL (1250 /ig/mL). This solution will be near, but not above, the limit of the
calibration range and will match the concentration of the QC samples from
Method 1662 (assuming 100% recovery).
7 7. GAS CHROMA TOGRAPHY
11.1 Table 2 summarizes the recommended operating conditions for the GC. Retention times for
the n-alkanes obtained under these conditions are given in Table 3. An example of the
separation achieved for diesel oil is shown in Figure 1. Other columns, chromatographic
conditions, or detectors may be used if the minimum level (Section 7.1) and the initial
precision and accuracy requirements (Section 8.2) are met.
11.2 Using a micropipette or microsyringe, transfer equal 100-/iL volumes of the sample, sample
extract, or QC standard extract (Section 10.2) and the TCB internal standard solution
(Section 6.2.1.3) into a GC injection vial. Cap tightly and mix thoroughly.
11.3 Inject 1 tiL of the sample extract or standard into the GC, using the conditions in Table 2.
11.4 Begin data collection and the temperature program at the time of injection.
11.5 If the area of any peak exceeds the calibration range of the system, dilute a fresh aliquot of the
extract by a factor of 10, mix 100 pL of internal standard with a 100-juL aliquot of the extract,
and reanalyze.
11.6 Compute the concentrations of the individual n-alkane peaks using the response factor for
hexadecane from the calibration data (Section 7.2.2.2).
12. SYSTEM AND LABORA TORY PERFORMANCE
12.1 At the beginning of each 8-hour shift during which analyses are performed, GC calibration and
system performance are verified. For these tests, analysis of the medium-level calibration
65
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Method 1663
standard (Table 1) and of the precision and recovery standard (Section 6.2.3) shall be used to
verify all performance criteria. Adjustment and/or re-calibration (per Section 7) shall be
performed until all performance criteria are met. Only after all performance criteria are met
may samples and blanks be analyzed.
12.2 Inject 1 /*L of the medium-level calibration standard (Table 1) into the GC instrument
according to the procedure in Section 11.
12.3 Retention times.
12.3.1 Retention time of the internal standard: The absolute retention time of the TCB
internal standard shall be within the range of 7.96 to 8.08 minutes.
12.3.2 Relative retention times of the n-alkanes: The retention times of the n-alkanes relative
to the TCB internal standard shall be within the limits given in Table 3.
12.4 Calibration verification: Compute the concentration of hexadecane based on the average
calibration factor (Section 7.2.2.2). The concentration shall be within the limits in Table 4. If
calibration is verified, system performance is acceptable and analysis of blanks and QC
samples may begin. If, however, the concentration falls outside of the calibration verification
range, system performance is unacceptable. In this case, correct the problem and repeat the
test, or recalibrate (Section 7).
12.5 Ongoing precision and recovery (OPR): If the extract is from Method 1662, the OPR standard
from that method shall be used and the specification for the OPR from Method 1662 in Table
4 shall be met; if not, a sample of diesel oil shall be diluted per the procedure in Section 10
and shall be used for the OPR test.
12.5.1 Analyze the appropriate OPR standard.
12.5.2 Compute the concentration of diesel oil in this standard per Section 14.2.
12.5.3 Compare the concentration with the limits for ongoing precision and recovery in
Table 4. If the concentration is in the range specified, the analytical processes are in
control and analysis of blanks and samples may proceed. If, however, the
concentration is not in the specified range, these processes are not in control. In this
event, correct the problem, re-extract the sample batch if the OPR is from
Method 1662, or redilute the oil sample (per Section 10.3) and repeat the ongoing
precision and recovery test.
12.5.4 Add results that pass the specifications in Section 12.5.3 to initial and previous
ongoing data. Update QC charts to form a graphic representation of continued
laboratory performance. Develop statements of laboratory data quality for diesel oil
by calculating the average percent recovery (R) and the standard deviation of percent
recovery (sr). Express the accuracy statement as a recovery interval from R 2sr to
R + 2sr. For example, if R = 95% and sr = 5%, the accuracy is 85 to 105%.
13. QUALITATIVE IDENTIFICATION
13.1 Qualitative identification is accomplished by comparison of data from analysis of a sample or
blank with data from analysis of the calibration verification standard (Section 12.4). Diesel
and crude oil are differentiated by the presence and concentration of the Cg-Cjo n-alkane peaks
in the chromatogram of extracts of the sample.
66
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Method 1663
13.1 Using the calibration data, establish the identity of the C9-Cy, n-alkane peaks in the
chromatogram of the sample.
13.2 Diesel oil is not present in the sample if there are less than 10 n-alkane peaks present in the
C9-C24 range at a signal-to-noise ratio equal to or greater than 3 for each peak, and if the QC
tests (Sections 8 and 12) for the sample set are acceptable. The experience of the analyst shall
weigh heavily in the determination of the presence of peaks at a signal-to-noise ratio of 3 or
greater.
13.3 If ten or more n-alkane peaks are present in the analysis of the sample, diesel oil, mineral oil,
or crude oil may be present. Mineral oil can be distinguished by its lower polynuclear
aromatic hydrocarbon content using Method 1654A. Some crude oils may be distinguished by
the presence and concentration of n-alkanes in the C^-C^ range. If peaks are present in the
Cjs-C^ range, the quantitative measurements in Section 14 are used as a final determination
that the oil is crude oil.
14. QUANTITATIVE DETERMINATION
14.1 Differentiation between diesel and crude oil.
14.1.1 Using the concentrations of the individual n-alkane peaks determined in
Section 11.6, sum the concentrations of the n-alkanes from C9 to C^, inclusive.
Similarly, sum the concentrations of the n-alkanes from C& to C^, inclusive.
14.1.2 Calculate the percentage of C^-C^ n-alkanes as follows:
Equation 3
Sum of €.,-€„. n-alkanes
Percent^ - CJ = J* * x 100
Sum of Cg-Cy, n-alkanes
14.1.3 If the percent of C^-C^ n-alkanes is greater than 1.2, the oil is crude oil.
14.2 Determination of diesel oil: Compute the concentration of diesel oil in the standard or QC
extract using the hexadecane peak only, and the response factor given in Section 7.2.2.2, using
the following equation:
67
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Method 1663
Equation 4
Crx (mg/mL) = _£
where:
Ca = Concentration of oil in the sample
C.u = Concentration of the internal standard, in mg/mL
As = Area of the peak to be measured
A^ = Area of the internal standard peak
(For RF, see Equation 1)
15. COMPLEX SAMPLES
15.1 The most common interferences in the determination of diesel oil are from mineral oil and
proprietary additives in drilling fluids, and from naturally occurring hydrocarbons from crude-
oil-bearing formations.
15.2 Mineral oil can be identified by its lower polynuclear aromatic hydrocarbon content using
Method 1654 A.
15.3 Crude oils can usually be distinguished by the percentage of C^-CM n-alkanes per Section 14
of this method. However, some crude oils may not produce peaks in the C^-C^ range.
15.3.1 Oil condensates from gas wells are low in molecular weight and will normally
produce chromatographic peaks in the C8-C16 range. If a sample of the gas
condensate crude oil from the formation is available, the oil can be distinguished from
diesel oil using the extract from this method and the n-alkane ratio determinations in
the section on qualitative determination in Method 1651.
15.3.2 Asphaltene crude oils with API gravities <20 may not produce chromatographic
peaks in the C^-C^ range. In this instance, the lack of peaks in the C^-Cy, range
cannot be used to prove that the oil is crude oil and not diesel oil. However, the
absence of ten peaks in the C9-C24 range can be used to demonstrate that diesel oil is
not present, per Section 13 of this method.
16. METHOD PERFORMANCE
Specifications in this method are adopted from EPA Method 1651 (Reference 5). Example
chromatograms of diesel oil and crude oil are shown in Figure 1.
68
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Method 1663
References
1. "Carcinogens—Working With Carcinogens." Department of Health, Education, and Welfare,
Public Health Service, Centers for Disease Control [available through National Technical
Information System, 5285 Port Royal Road, Springfield, VA 22161, document no. PB-
277256]: August 1977.
2. "OSHA Safety and Health Standards, General Industry [29 CFR 1910], Revised."
Occupational Safety and Health Administration, OSHA 2206. Washington, DC: January 1976.
3. "Safety in Academic Chemistry Laboratories (3rd Edition)." American Chemical Society
Publication, Committee on Chemical Safety. Washington, DC: 1979.
4. "Handbook of Analytical Quality Control in Water and Wastewater Laboratories." USEPA,
EMSL-Ci, EPA-600/4-79-019. Cincinnati, OH: March 1979.
5. "Method 1651, Total Oil and Diesel Oil in Drilling Muds and Drill Cuttings by Retort,
Gravimetry, and GC/FID." Available from the EPA Sample Control Center, 300 N. Lee St.,
Alexandria, VA 22314.
69
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Method 1663
Table 1. Concentration of Calibration Standards
Calibration Solution Concentration fug/mLJ
Ana/yte
n-decane
n-hexadecane
n-tetracosane
Diesel Oil
Low
--
10
—
—
Medium
40
40
100
1250
High
—
200
—
--
Table 2. Gas Chromatographic Operating Conditions
Injection port, transfer fine, and detector temperatures: 275°C
Column temperature program:
Initial temperature: 90°C
Initial time: 0 minutes
Ramp: 90°C-250°C @ 5°C per minute
Final temperature: 250°C
Final hold: 10 minutes or until all peaks have eluted
Carrier gas and flow rates:
Carrier: Nitrogen or helium
Velocity: 20-40 cm/sec @ 90°C
Split ratio: 0-120:1**
Makeup gas: As required by manufacturer
Hydrogen and air flow rates: As specified by manufacturer
Detector amplifier settings: 10"n amp full scale. Attenuation is adjusted so that the highest
peaks are on scale in the most concentrated standard.
Recorder: Chart speed of 1 -2 cm/min (fixed)
* Conditions are approximate and can be adjusted to meet the performance criteria in Section 12
(see the note in Section 7.1).
**Lower split ratios may give more reproducible results.
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Method 1663
Table 3. Retention Times and Relative Retention Time Limits for n-Alkane Peaks
Retention Time
Compound
TCB
n-C12
n-C13
n-Cu
n-C16
n-C16
n-C17
n-C18
n-C19
n-C20
n-C21
n-C22
n-C23
n-C24
Mean
(minutes)
8.0
9.9
12.6
15.3
17.9
20.4
22.9
25.2
27.3
29.4
31.5
33.4
35.3
37.1
Relative
1.00-1.00
1.22-1.24
1.55-1.57
1.89-1.92
2.21-2.25
2.52-2.56
2.82-2.88
3.12-3.15
3.39-3.43
3.66-3.71
3.90-3.97
4.14-4.21
4.37-4.45
4.58-4.69
Table 4. QC Acceptance Criteria
Criterion Units
Minimum Level2 fjg/mL
Method Detection Limit3 mg/kg
Initial Precision and Recovery
Precision (RSD)4 mg/mL
Recovery mg/mL
Calibration Verification5 pg/mL
Ongoing Precision and Recovery4 mg/mL
Matrix Spike Recovery4 pet
Duplicates RPD
Diesel
Oil1
100
100
Oil from Method
1662
0.23
1.00-1.35
0.98-1.37
0.73-1.14
16
n-hexadecane
10
34-46
1 CAS Registry number 68534-30-5; #2 diesel oil used for these tests.
2 This is a minimum level at which the analytical system shall give recognizable signals and
acceptable calibration points.
3 Estimated; 40 CFR Part 136, Appendix B; MDL is diesel oil in mud.
4 Test concentration in diluted extract = 1.25 mg/mL
5 Test concentration = 40 //g/mL
71
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Method 1663
Crude Oil
O
in
i—
O
l/sl
O
CM
O
Diesel Oil
A 52-010-003
Figure 1. Chromatograms of Crude Oil and Diesel Oil, Showing Differences in the C25-C30
Range
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