METHOD 1664 29 MARCH 1994 DRAFT
'OIL AND GREASE' and 'PETROLEUM HYDROCARBONS'
N-HEXANE EXTRACTABLE MATERIAL (HEM) AND SILICA GEL TREATED N-
HEXANE EXTRACTABLE MATERIAL (SGT-HEM) BY EXTRACTION AND
GRAVIMETRY
1. SCOPE AND APPLICATION
1.1 This method is for determination of n-hexane extraccable material (HEM) and n-
hexane extracuble material thai is not adsorbed by silica gel (SGT-HEM) in surface
and saline waters and industrial and domestic aqueous wastes. Extracuble materials
that may be determined are relatively non-volatile hydrocarbons, vegetable oils,
animal fats, waxes, soaps, greases, and related materials.
\
1.2 This method is for use in the Environmental Protection Agency's (EPA's) survey and
monitoring^programs "nA^r the Federal Water P«11nTJ^>t- Control Act and
Amendments! "Oil and grease" is a conventional pollount defined inthe Act and
codified -at*40 CFR 401:16.* Joe term- "n-hexane extnctable material-reflects that
this method can be applied to materials other than oils and greases. Similarly, the
term "silica gel treated n-hexane extracuble material" reflects that .this method can
be applied to materials other than aliphatic petroleum hydrocarbons that are not
adsorbed by silica gel.
1.3 This method is not applicable to measurement of materials that volatilize at
temperatures below approx 85°C. Petroleum fuels from gasoline through (f2 fuel oil
may be partially lost in the solvent removal operation.
1.4 Some crude oils and heavy fuel oils contain a significant percentage of materials that
are not soluble in n-hexane. Accordingly, recoveries of these «"aTfriqlT may be low.
1.5 This method is capable of measuring HEM and SGT-HEM in the range of 5 to 1000
•
mg/L, and may be extended to higher levels by analysis of a smaller sample volume
collected separately.
29 Much 1994 Dnfc
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1.6 For this method, the Method Detection i ; ;t (MDL; 40 CFR 136, Appendix B) for
HEM has been determined as 5 nig/L (Reference 16.1), and the Mrimum Level
(Reference 16.2) has been set at 20 mg/L (Reference 16.1).
1.7 This method is ‘perforinance.based. The analyst is permitted to modify the method
to overcome interferences or lower the cost of measurements, provided that all
performance criteria in this method are met. The requiremetits for establishing
method equivalency are given in Section 9.1.2.
1.8 Any modification of this method, beyond those expressly permitted, shall be
considered a major modification subject to application and appz oval of alternate test
procedures under 40 CFR 136.4 and 136.5.
1.9 Each analyst who uses this method must demonstrate the bility to generate
acceptable results using the pr 9 cedure in Section 9.2. _ _
SUMMARYOFMETH9D
2.1 A iL sample is acidified to pTH <2 and serially extracted three times with n-hexane
in a separatory funnel. The extract is dried over sodium sulfate.
2.2 The solvent is evaporated from the extract and the HEM is weighed... If the HEM
is to be used for deterrnin2tion of SGT-HEM, the HEM is redissolved in n-hexane.
2.3 For SGT-HEM determination, 3 g of silica gel is added to the solution conr rtng the
redissolved HEM to remove silica gel adsorbable materials. The solution is filtered
to remove the silica gel, the solvent is evaporated, and the SGT-HEM is weighed.
2.4 Quality Is assured through calibration and testing of the extraction, conecitration,
and gravimetric systems.
3. DEFINITIONS
3.1 HEM and SGT-HEM are method-defined analytes; i.e., the definitions of both HEM
and SGT-HEM are dependent on the procedure used. The nature of the oils and/or
Method i 2 29 Mitch 1994 Draft
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greases, and the presence of extractable non-oily matter in the sample will isifluence
the fn2rerial measured and interpretation of results.
3.2 Definitions for terms used in this method are given in the glossary as the end of the
method.
4. INTERFERENCES
4.1 Solvents, reagents, glassware, and other sample -procescing hardware may yield
artifacts that affect results. Specific selection of reagents and purification of solvents
may be required.
4.2 All materials used in the analysis shall be demonstrated to be free from interferences
under the conditions of analysis by running laboratory blanks as described in Section
9.4.
4.3 Glassw. s cleaned by... 2cb ng in hot water cont in1Lr’g rl.c gent , rincngysth tap
L r i.
p -
and distilled water, and rinsing with solvent or bakingr. .3oiling fi that will
con! ifft’extract 4 id ie2re d oven/ )5 - 115°C Jttored in a
desiccator.
4.4 Sodium sulfate and silica gel fines have been shown to inflate results for HEM and
SGT-HEM. If the filter paper specified in this method is inadequate for removal of
these fines 1 use of a 0.45-micron filter is recommended.
4.5 Interferences extracted from samples will vary consinerably from source to source,
depending upon the diversity of the site being sampled. For those instances in which
samples are thought to consist of complex matrices conr 2ir1ng substances (such as
particulates or detergents) that may interfere with the extraction procedure, a ,inalTer
sample may need to be collected for analysis.
kthod16 4 3 2 cb 1994 Drift
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5. SAFETY
5.1 The toxicity or carcinogenicaty of each reagent used in this method has not been
precisely determined; however, each eli.mical should be treated as a potential health
h ird. Exposure to these chemicals should be reduced to the lowest possible level.
5.2 n.H,yane has been shown to have increased neurotoxic effects over other hexanes
and some other solvents. Tnh2lation of zi-hezane should be rnnrn d by performing
all operations with n-hexane in a hood or well-ventilated area.
5.3 Unknown samples may contain high concentrations of volatile toxic compounds.
Sample containers should be opened in a hood and handled with gloves to prev z1t
exposure.
5.4 This method does not address all safety kvues associated with its use. The lahoratry
is resp nsib1e for n ’nr tntnga safe work environm m.an curreiijaw2rena’cs file
i
of OSHA regulations garding the safe handling of t e-cbe nicals spe fled in this
I
. __ p
rnethod- A referenoe le oLmateria l- detrdata sheets SDSs) should be made
available to all personnel involved in these analyses. Additional information on
laboratory safety can be found in References 16.3 - 16.5.
6. EQUIPMENT AND SUPPLIES
6.1 Sampling equipment.
6.1.1 Sample collection bottles.
6.1.1.1 Glass, appro im Iy1 L, with PTFE-lined screw cap.
6.1.1.2 Glass, appro ’rn ly 100 mL, vith PTFE4ined screw cap.
6.1.2 Cl iiing.
6.1.2.1 Bottles-Detergent water wash, tap water rinse, cap with aIun ’num
foil, and bake at 200 - 250 C for 1 h minimum prior to use. Solvent
rinse may be used in place of baking.
Mnhod i6 4 4 March 1994 Draft
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6.1.2.2 Linen—Detergent waxer wash, tap waxer and solvent rinse, and bake
at 110- 200 ‘C for I h m i nimum prior to use.
6.1.3 Bottles and LIners must be lot -certified to be free of artifacts by running
laboratory blanks aicording to this method. If blanks from bottles and/or
linen without cleaning or with fewer c l eaning steps than required above
show no detectable materials (per Section 9.4), the bottle and liner cleaning
steps that do not e lim i nate these artifacts may be omitted.
6.2 Equipment For glassware cleaning.
6.2.1 Laboiarory sink with overhead fume hood.
6.2.2 Oven: Capable of miinrsining a temperature within ± 5°C in the range of
100- 250°C.
— S — J
6.3 Equipment for sample Sracti n.
V
6.3.1 Balanà, top loadini capable oG hing SOC :±000t within ±i%.
— . __ • — a — •
6.3.2 G Lass stirring rod. .
6.3.3 Separatory funnel, 2000 nL, with PIPE stopcock.
6.3.4 Funnel, large, glas for pouring sample into separatory fpnnel.
6.3.5 Centrifuge, capable of spkning at least four 100 niL glass centrifuge tubes at
2400 rpm minimum.
6.3.6 Centrifuge tubes, 100 niL glass.
6.4 Equipment for removal of water, and sodium sulfate and silica gel fines.
6.4.1 Liquidfunnel glass.
6.4.2 Filter paper, Whatrnan No.40 (or equivalent), to St funnel .
6.5 Equipment for solvent evaporation.
6.5.1 Water bath, capable of mshtrainng a temperature of approximately 85°C.
6.5.2 Flask, boiling, 125 niL (Corning No. 4100 or equivalent).
ihod l%4 5 29 March 1994 Dré
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6.5.3 Distilling head, Claisen, or equivalent.
6.5.4 Distilling adaptor (attached to the distilling head and to the waste collection
flask for recovery of solvent).
6.5.5 Waste collection flask (attached to the distilling adaptor for collection of the
distilled solvent).
6.5.6 Ice bath (to aid in the condensation and collection of the distilled solvent).
6.5.7 Vacuum, pump or other source of vacuum.
6.5.8 Desiccator—Cabinet- or jar-type, capable of keeping the boiling flask (Section
6.5.2) dry during cooling.
6.6 Equipment for removal of adsorbable materials.
6.6.1 Magnetic stirrer.
6.6.2 - PTFE-coated m ji stirring bars.. — -1
6.6.3 Graduated cylinder, 5O mL-capabi of measurmg-* 5 mL.
6.7 Analytical Balance-Capable of eigbing 0ti-mg -.
7. REAGENTS AND STANDARDS
7.1 Reagent water-Water in which HEM is not detected at the MDL of this method.
Bottled distilled water, or water prepared by passage of tap water through activated
carbon have been shown to be acceptable sources of reagent water.
7.2 Hydrochloric acid, 1:1. Mix equal volumes of conc. HC1 (ACS) and reagent water.
7.3 n-Hcxane and acetone-Pesticide quality, or equivalent.
7.4 Sodium sulfate, anhydrous crystal.
7.5 Boiling chips, silicon carbide or PTFE.
7.6 Silica gel, anhydrous, 60 to 200 mesh (Davidson Grade 50 or equivalent)-Dry at 200
250°C for 24 h minimum and store in a desiccator or tightly sealed container.
Determine the hexane soluble material content of the silica gel by extracting 30 g of
MethOd 1664 6 rh1994 Drdi
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silica gd with ti-hexane and evaporating the n-hexane to dryness. The silica gel must
contsin less than 5mg of hexane soluble material per 30 g(<0.17 xng/g).
7.7 Hexadecane and stearic acid standards-purchased as neat materials of known purity
and composition. Compound purity must be 98 percent or greater.
7.8 Hexadecane/stearic acid (1:1) spi 1 1 ng solution-Prepare in acetone a x a concentration
of 4 rng/mL each.
7.8.1 Place 400 ± 4 mg stearic acid and 400 ± 4 mg hexadecane in a 100 ml.
volumetric and fill to the mark with acetone.
NOTE: The solution may require warming for complete dissolution
of stearic acid.
7.8.2 After the hexadecane and stearic acid have dissolved, tratisfer the solution to
.. a 100: 150 uul a With PTFE4ined cap. MarlE hC.SQjutiOn jeveLon the vial
and store in the dark at’ room temp rature. i — .€
i ‘: • _•••• ‘ F • --
7.8.3 -n1T ediately- rior o.use, vdify th 4evel esrthe viaL and brI ig-to volume
with acetone, if required. Warm to redissolve all visible precipitate.
NOTE: If there is doubt of the con ntration, remove 5.00± 0.05
ml. with a volumetric pipet, place in a tared weighing pan, and
evaporate to dryness in a fume hood. The weight must be 40 ± 1
mg.
7.9 Precision and recovery (PAR) standard—Spike 5.00 ± 0.05 ml. of the
hexadecane/atearit acid sp lring solution (Section 7.8) into 950. 1050 niL of reagent
water to produce centratsocis of approiinsately 2oingfk each of 4iezadecane and
stearic acid. The PAR standard is used for the determination of initial precision and
recovery (Section 9.2) and ongoing precision and recovery (Sectign 9.6).
á hod t ós 7 29 March 1994 Drth
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7.10 - The spiking solutions should be checked frequently for sips of degradation or
evaporation and must be replaced after six months, or sooner if degradation has
occurred.
8. SAMPLE COLLECTION, PRESERVATION, AND STORAGE
8.1 Collect approTrnl2tely one liter of representative sample in a glass bottle following
conventional sampling practices (Reference 16.6), except that the bottle must not be
pre.rinsed with sample before collection.
8.1.1 If analysis is to be delayed for more than a few hours, preserve the sample by
adding 5 mL of 1:1 HC1 solution (Section 7.2) at the time of collection, and
refrigerate at 0 - 4 °C.
8.1.2 If a sample is known or suspected to contain greater than 1000 mg/L of
extractable material; colle& an additioiial appro iimstely 100 mLsample n a
glass bottle. Add 0.5 rnL of 1i1) Cl soluti ñ the smaller sample if
preservation is necessary.
8.2 Collect an additional two samples (1-L, 100-mL, or both) for each set of ten samples
or less for the matrix spike and matrix spike duplicate.
8.3 Because extractable matter may. adhere to sampling equipment and result in
measurements that are biased low, collection of a composite sample is impractical.
Therefore, if it is necessary to obtain an average concentration over an extended
period of time, individual grab samples collected it prescribed time intervals must be
analyzed ieparately and the concentrations averaged. -
8.4 All samples must be refrigerated at 0 - 4 °C from the tme of collection until
extraction (40 C R 136, Table Ii).
8.5 All samples must be analyzed within 28 days of the date and time of collection (40
CFR 136, Table fl)..
1664 8 29March 1994 Draft
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9. QUALITY CONTROL
9.1 Each laboratory that uses this method is required to operate a formal quality
assurance program (Reference 16.7). The mintmum requirements of this program
consist of an initial demonstration of laboratory capability, ongoing analyses of
standards and blanks as a test of continued performance, and analyses of matrix spike
(MS) and matrix spike duplicate (MSD) samples to assess accuracy and precision.
Laboratory performance is compared to established performance criteria to determine
if the results of analyses meet the performance cl,aractenstics of the method.
9.1.1 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 9.2.
9.1.2 1n recognition of advances that are occurring in m2IytiCal hnology, the
4 j.
- analyst is permitted certain options to improveieparations or lower tWe costs
- .. -.- • r—4 . 5’ •
----of measurexn nts. Thesr ep ns inck e- alternate tracrion and
concentrari ,n devices and procedures such as solid-phase extraction.
Alternate determinative techniques, such as the substitution of infra-red
spectroscopic or ivninuno-assay techniques, and ekinges that degrade method
performance, are not allowed. If an analytical technique other than the
techniques specified in this method is used , that technique must have a
specificity equal to or better than the specificity of the techniques in this
method for HEM and/or SGT-HEM in the sample of nterest.
9.1.2.1 Each tame a modification is mwle ic, ilth method, -the analyst is
required to repeat the procedure in Section 91 If the detection limit
of the method will be affected by the change , the laboratory is
required to dempostrate rhavthe MDL (40 CFR 136, Appendix B) is
lower than one-third the regulatory compliance level or lower than
Method 1664 9 29 Match 1994 Drift
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the MDL in this method, whichever is higher. If calibration will be
affected by the ktnge , the analyst must recalibrate the instrument
per Section 10.
9.1.2.2 The laboratory is required to maintain records of modifications made
to this method. These records include the following, at a mlnmum:
9. 1.2.2.1 The names, titles, addresses, and telephone numbers
of the analyst(s) who performed the analyses and
modification, and of the quality control officer who
witnessed and will verify the analyses and
modification.
9.1.2.2.2 A listing of pollutant(s) meas’ured (HEM and/or SGT-
E 1 — .
. I ,iP. i
3.11.2.3 - A narrative sr tng reaso i(s)4 r the modification.
i_I.- _
9.1.2.2k— Resuki froiu all qualit ontro1 (QC)-th comparing
the snodiflec methodto this method, including
a) Calibration (Section 10).
b) Calibration verification (Section 9.5).
c) Initial precision and recovery (Section 9.2).
d) Analysis of blanks (Section 9.4).
e) Accuracy asse ni.nt (Section 9.3).
f) Ongoing precision and recovery (Section 9.6).
9:1.2.2.5 . Data that will aliow -an independcnt -reviewer to
validate each determination by tracing the instrument
output (peak height, area, or other signal) to the final
result. These data are to include:
a) Sample numbers and other identifiers.
M hod 4 10 29 March 1994 Draft
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b) Extraction d2re5 .
c) Analysis dates and tim c .
d) Analysis sequence/nm chronology.
e) Sample weight or volume (Section 11.1.4).
f) Extract volume for SGT-HEM (Section 11.5).
g) Make and model of analytical balance and weights
traceable to NIST.
h) Copies of logbooks, prnter tapes, and other
recordings of raw data.
Data system outputs, and other data to link the raw
data to the results reported..
9.1.3 .Analyses of m 4 p re and mat, spike du? •&amPIes ary uired to
demonstrate method . curacy and precision indineni or matri.lhterferences
_t4rence,Leà y L):-L procedure AQCcriteria
for spiking are described in Section 9.3.
9.1.4 Analyses of laboratory blanks are re uired to demonstrate freedom from
contamination. The procedures and criteria for analysis of a blank are
described in Section 9.4.
9.1.5 The laboratory shall, on an ongoing basis, demonstrate through calibration
verification and analysis of the ongoing precision and recovery sample that
the analysis system is in control. These procedures axe d.”-’ibed in Section
9.5 and 9respectwely.
9.1.6 The laboratory should n intain records to the quality of data that is
generated Development of ac aracy sta e nents is described in Sections 9.3.7
and 9.6.3.
1 h ..d 4 11 29 Much 1994 Drift
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9.2 Initial
9.2.1,
9.1.7 The deterimnition of HEM and/or SGT-HEM are controlled by the
analytical batch. Anazialytical batch is the set of samples extracted at the
e time, to a rn r ’mum of 10 samples. Each analytical batch of 10 or fewer
samples must be accompanied by a laboratory blank (Section 9.4), an ongoing
precision and recovery sample (OPR., Section 9.6), and a matrix spike and
matrix spike duplicate (MS/MSD, Section 9.3), resulting in a r, ini1, um of five
analyses (1 sample, 1 blank, 1 OPR, 1 MS. and 1 MSD) and a maximum of
14 analyses (10 samples, 1 blank, 1 OPR, 1 MS, and I MSD) in the batch. If
greater than 10 samples are to be extracted at one time, the samples must be
separated into analytical batches of 10 or fewer samples.
demonstration of laboratory capability.
Method Detectum .Iimit-To establish the SGT-
HEM, the analyé shall determine *bà MDL p in .40 CFR 136,
----Appendix B £g th, appar*( s, L t5 be used in
the practice of this method. An MDL less than or equal to the MDL in
Section 1.6 must be achieved prior to the practice of this metbod.
9.2.2 Initial precision and recovery (IPR.)-To establish the ability to generate
acceptable precision and accuracy, the analyst shall perform the following
operations:
9.2.2.1 Extract and evaporate four samples of the PAR standard (Section 7.9)
according to the procedure beginning in Section 11.
9.2.22 Using the results of the set of lauranalyses, tompute the average
percent recovery (X) in mg/L and the standard deviatioa of the
percent recovery (a) for HEM and for SGT-HEM (if determined).
9.2.2.3 Compare a and X with the corresponding limits for initial precision
and recovery in Table 1. If a and X meet the acceptance criteria,
M hod 1664
11
29 March 1994 Draft
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system performance is acceptable and analysis of samples may begin.
If, however, a exceeds the precision limit or X falls outside the range
for recovery, system performance is unw’ceptable. In this event
correct the problem, and repeat the test.
9.3 Matrix spikes—The laboratory must spike, in duplicate, a mnimum of 10 percent of
all samples (one sample in each batch of ten samples) from a given sampling site.
The two sample aliquots shall be spiked with the h i 1 ecane/stearic acid spiking
solution (Section 7.8).
9.3,1 The concentration of the spike in the sample shall be determined as follows:
9.3.1.1 If, as in compliance monitoring, the concentration of HEM or SGT-
HEM in the sample is being checked against a regulatory
. concen iñ 1iniit, the spi ng level s ll t that limit or at 1 to
£
, . . 4/ 11 - t__ i
15 times hixJ’er than th k ound itration o4the sample
9.3.1.2 Ii the concentration of HEM or SGT-HEM in a sample is°not being
checked against a limit, the spike shall be at the concentration of the
precision and recovery standard (Section 7.9) or at 1 to 5 times higher
than the b kground concentration, whichever concentration is
higher.
9.3.2 Analyze one sample aliquot out of each set of ten samples from each site
according to the procedure Ig nnng in Section 11 to determine the
b ekground concentration (B) of HEM or SGT-HEM.
9.3.2.1 If necessary, prepare a standard solution appropriate to produce a
level in the sample at the regulatory compliance limit or at 1 to 5
times the background concentration (per Section 9.3.1).
Method l 64 13 Ma,ch 1994 Drth
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9.3.2.2 Spike two additional sample aliquots with the spiking solution and
analyze these aliquots to determine the concentration after spiking
(A):
9.3.3 Calculate the percent recovery (P) of HEM or SGT-HEM in each aliquot
using the following equation:
Equation I
100(A-B)
T
where:
A - Measured concentration of analyte after spiking
B - Measured background concentration of HEM or SGT-HEM
T - True concentration of the spike (40 zng/L)
NOTE. When deteriiiining SGT-HEM, the true concentration (Tj
must be divided by 2 to reflect the concentration of hexadecane that
ri’rnainaRer.removalof stearc acid ( 2O mg/1
ph ,. ,1
9.3.4 Compare the percent the HEM-or SGT-HEM with the
- oilespondingt C TablI
9.3.4.1 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 9.6) for the analytical batch is within the acceptance criteria
in Table 1, an interference is present. In this case, the result may not
be reported for regulatory compliance purposes..
9.3.4.2 If 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 chill 1,eidentified and
corrected, and the sample analytical reanalyzed.
9.3.5 Compute the relative percent difference (RPD) between the two results (not
between the two recoveries) ucng the following equation:
Method 1664
14
29March 1994 D,afe
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Equation 2
1D 1 -D 2 1
R.PD- z lOO
(D 1 + D)/2
where
D 1 Concentration of HEM or SGT-HEM in the sample
D 2 - Concentration of HEM or SGT.HEM in the second (duplicate)
sample
9.3.6 The relative percent difference for duplicates shall meet the acceptance criteria
in Table 1. ffhecriteriaarenotmet,theacalsystemis udgedtobe
out of control, and the problem must be immediately identified and
corrected, and the analytical batch reanalyzed.
9.3.7 As part of the QC program for the laboratory, method precision and
accuracy for samples should be assessed and records should be m intained.
Aker the analys of4 v e spiked samples in whieb rk oves passes the test
• • r I
in Sec oo -3 .4 comp ne the average percent teco y (P) and the standard
of eh pe recu C p EXP t LS accuracyi.Lea t as
percent recbvery interval from P 1 . 2s to P + 2s . For r mple, if P — 90%
and a — 10% for five analyses of HEM or SGTHEM, the.accuracy interval
is expressed as 70-110%. Update the accuracy assessment on a regular’ basis
(e.g., after each five to ten new accuracy measurements).
9.4 Laboratory blanks—Laboratory reagent water blanks are analyzed to demonstrate
freedom from cont min2tion.
9.4.1 Extract and concentrate a laboratorj reagent water blank initially and with
each analytical batch. The blank usr be ,ub,ecteA t the act ___
procedural steps ai a sample.
9.4.2 11 greaser than 5 mg/L of material is detected in a blank , analysis of samples
is baited until the source of cOnI Imn2tioD is elir, in ,ed and a blank shows
no evidence of cont2mrtItion.
Method 1664 15 9 5 brth 1994 Drth
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9.5 Calibration verification—Verify calibration of the balance per Section 10 before and
after each analytical batch of 14 or fewer m curements. (The 14 measurements will
normally be 10 samples, 1 blank, 1 OPR.I, 1 MS and I MSD.) If calibration is not
verified after the measurements, recalibrate the balance and reweigh the batch.
9.6 Ongoing precision and recovery-To demonstrate that the analysis system is in
control, and acceptable precision and accuracy is being n nrained with each
analytical batch, the analyst shall perform the following operations:
9.6.1 Extract and concentrate a precision and recovery standard with each
analytical batch according to the procedure be nning in Section 11.
9.6.2 Compare the concentration with the limits for ongoing precision and
recovery in Table 1. If the concentration is in the range specified, the
extraction, evapora son , and weighii g process in -contro nA analysis of
1’ •‘
blanks’and sam 1es may proceed.’i however, tii concentration’ is not in the
.‘I.. / . : ___ ___
-specIfied range,the analytical procesris not id 1untrol. In thir v nt, correct
the problem, re- tract the analytical batch, and zepeat the ongoing precision
and recovery test.
9.6.3 The laboratory should add results that pass the speci&ation in Section 9.6.2
to IPR and previous OPR data and update QC charts to form a graphic
representation of continued laboratory performance. The laboratory should
also develop a statement of laboratory data quality for each analyte by
calcuJ ting the average percent recovery (R) and the standard deviation of
percent recoveiy (s). Express the accuracy a recovery interval from K - 2s,
toR+2s. Forexample,ifR—95%ands—5%,theacc racyis85%to
105%.
9.7 Quality control sample (QCS)-it is suggested that the laboratory obtain a quality
control sample from a source different from the source for the hexadecane and stearic
M&hod 1644 16 29 March 1994 Drift
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acid used routinely in this method (Section 7.8), and that the QCS be used for
verification of the concentrations of HEM and SGT-HEM using the procedure given
in the note in Section 7.8.3.
The specifications contained in this method can be met if the apparatus used is
scnspulously cleaned and dedicated for the determination of HEM and SGT-HEM.
The standards used for initial precision and recovery (IPR, Section 9.2), matrix spikes
(MS/MSD, Section 9.3), and ongoing precision and recovery (OPR , Section 9.6)
should be identical, so that the most precise results will be obtained.
9.9 Depending upon specific program requirements, field replicates and field spikes into
samples may be required to assess the precision and accuracy of the sampling and
sample transporting techniques.
10. CALIBRAI1ON AND IANDARD1ZATION
10.1 Calibrate the a1yticaJ bal2rI e at 5 mg 0O0 mg u ng-clau wei its.
10.2 Calibratiori’hall be thn .10% 4G5 .w 5 tng- d-± 0.5% (5 ac 1000 mg.
If values are not within these limits, recalibrate the balance.
11. PROCEDLTRE
NOTE This method is entirely empirical. Precise and accurate results can be
obtained only by strict adherence to all details.
11.1 Preparation of the analytical batch.
11.1.1 Bring the analytical batch of samples, including the sample aliquots for the
MS and MSD, to room temperature.
11.1.2 Place approx2mately 1000 inL (950. 1050 mL)of Te2éen ater (Section 7.1)
in a clean sample bottle to serve as the laboratory bhnlr
11.1.3 Prepare the OPR (Section 9.6) niing the PAR standard (Section 7.9).
shod 16 4 17 March 1994 Dr
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11.1.4 Either mark the sample bottles at the water meniscus or weigh the bottles for
later determination of sample volume. Weig1i ng will be more accurate.
Mark or weigh the MS/MSD and the blank.
11.2 pH verification.
11.2.1 Verify that the pH of the sample is <2 titing the following procedure:
11.2.1.1 Dip a glass stirring rod into the well mixed sample.
11.2.1.2 Withdraw the stirring rod and allow a drop of the sample to
fall on or touch the pH-paper. NOTE: Do not dip the pH
paper into the bottle or touch it to the sample on the lid.
11.2.1.3 ‘ Rinse the stirring rod with a rna11 portion of n-hexane that
will be used for extraction (to e ure that no extractable
inthe
11.2.2 ‘4fthe
1 liter sample.
If a smaller sample volume, was collected, u e a proportionately
smaller amount of HC I solution. If the sample is at high pH, use a
proportionately larger amount of HQ solution.
11.2.3 Add the appropriate amount of HQ solution to the blank , OPR, MS, and
MSD. -
11.2.4 Replace the cap and thiL the bottle to mix thoroughly. Cheek the pH of
the saxnple’asing the procedurein Section 11.2.1.1 11 .2.h34dd more acid
to the sample if necessary and retest if ne essary.
11.3 Extraction
11.3.1 Tare a boiling flask conta r ng 3-5 boiling chips as follows:
Method 1664
18
29 March 1994 Dn*
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11.3.1.1 Place the flask contanng the chips in an oven at 105 - 115°C
for a mrninlum of 2 h to dry the flask and chips.
11.3.1.2 Remove from the oven and ; kvnediately transfer to cool in
a desiccator.
113.1.3 When cool, remove from the desiccator and weigh
; diatdy on a calibrated balance (Section 10).
11.3.2 Pour the sample into the separatory funnel.
11.3.3 Add 30 mL n-hexane to the samp 1 e bottle and seal the bottle with the original
bottle cap. Shake the bottle to rinse all interior ‘surfaces of the bottle,
including the lid of the bottle cap. Pour the solvent into the separatory
funnel.
11 .3.4 Extract the sample by halrng the s arasory fiinneh”igorous1 !for 2-minutes
- I lL”
with periodic ventinginto a lioq4jo release ex s premire.
k ___
11.3.5 Allow the organic layer to separate om the aqueous phase br a mi prnum
of 10 mm. If an emulsion forms between the ph es and the emulsion is
greater than one-third the volume of the solvent layer, the analyst must
employ meehanical techniques to complete the phase separation. The
optimum technique depends upon the sample, but may include stirring,
filtration through glass wool, centrifugation, or other physical methods.
Alternatively, solid-phase or other extraction techniques may be used to
prevent emulsion formation, provided that the requirements in Section 9.1.2
are met.
11.3.6 Drain the aqueous layer (lower layer) into the origin4 sample container.
Drain a a nount of the organic layer into the sample container to
n ninui,e the amount of water re na ’i’ ng in the separatory funnel.
Me hod1664 19 29Mas b1994DTII
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11.3.7 Place 10 g azihydrous Na 2 SO 4 in a filter in a filter funnel and rinse with a
irn ill portion of n-hexane. Discard the rinsate.
11.3.8 Drain the n-hexane layer (upper layer) from the separatory funnel through
the Na 2 SO 4 into the preweighed boiling flask con?2ining the boiling chips
(Section 11.3.1.3).
11.3.9 Repeat the extraction (Sections 11.3.3- 11.3.6 and 11.3.8) twice more with
fresh portions of n-hexane, combining the extracts in the boiling flask.
11.3.10 Rinse the tip of the separatory funnel, the filter paper, and the funnel
with 2- 3 fTfl ll (3 5 znL) portions of n-hexane collect the rinsings
in the flask.
11.3.11 A rnillcy extract indicate the presence of water. If the exteact is.
-. milky, allnw the solution to settle for. .u iopne hout,to4llow the
water to’sink to the bottor . Drain the-olvent layer (upper layer)
p
---- through ,odium sulfa e toLove -excess water r-in Sectipns
11.3.7-11.3.8.
11.3.12 If SGT-HEM only is to be determined, proceed to Section 11.5.
11.4 Solvent evaporation.
11.4.1 Connect the boiling flask to the distilling head and evaporate the solvent by
imniersing the lower half of the flask in a water bath at 85°C. Collect the
solvent for reuse. The apparatus set-up for solvent recovery typically cons sts
of a distillation adaptor with a driptip connected on one end to the boiling
flask and on the other end (the drip tip end) to a solvent recovery flask that.
is placed in an ice water bath.
11.4.2 When the temperature in the distilling head reaches 70°C or the flask appears
dry, remove the distilling head. Sweep out the flask for 15 seconds with air
to remove solvent vapor by inserting a glass tube connected to a vacuum
M hod1 4 20 9Mucbl994Dfth
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source. Inirnediately remove the flask from the heat source and wipe the
ij cje swlace dry to remove excess moisture and fingerprints.
NOTh The analyst should carefully monitor the flack during the
final evaporation stages to assure that all of the solvent is removed
and at the çarn time to prevent loss of the more volatile sample
constituents.
11.4.3 Inspect the residue in the boiling flask for crystals. Crystal formation is an
indication that sodium sulfate may have dissolved and passed into the taxed
boilixg flask. This may happen when the drying capacty of the sodium
sulfate is exceeded or if the sample was not adjusted to low pH. U crystals
are observed, redissolve the utract in n-hexane, filter into another taxed
&T flask, an4 r.peat the eva orjion Pro e . $. ,âIionsfr1!.4.1 1.4.2).
11.4.4 cool he bo,bv g flask in a desicca r for at le -J’inutes an determine
tofer nthe 4 ,a -L _
114.4.1 11 the extract was from the HEM procedure determine the
HEM (Wb) by subtracting the tare weight (Section 11.3.1)
from the total weight of the flask
11.4.4.2 If the extract was from the SGT-HEM procedure (Section
11.5.5), determine the weight of SGT-HEM (W) by
subtracting the tare weight from the total wtighi of the flask.
11.4.5 Determine the origin2l sample volume (V) in liters by fllng the sample
bottle tothe ark with water and measunng he volumeof water in ii to
2 L graduated cylinda.r. lithe sample weight was used (Section 11.1.4), weigh
the empty bottle and cap and determine V 1 by difference, assuming a sample
density of 1.00.
____1W 21 9 March t 94 Dr
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113 SGT-HEM determination.
11.5.1 Silica gel capacity-To ensure that the capacity of the silica gel will not be
exceeded, the amount of HEM must be known. -
11.5.1.1 If isis known that the HEM is less than 100 mg, the analyst
may proceed with the determination of SGT-HEM per
Sections 11.5.2 - 11.5.5 without determination of HEM.
11.5.1.2 If, however, the HEM is not known, HEM must first be
determined ucing the procelure in Sections 11.3- 11.4.
11.5.2 Extractable materials in silica gel-The amount of silica gel that can be used
for adsorption in the SGT-HEM procedure below has been Iimied to 30 g
because of concerns about possible extractable impurities in the silica gel.
...Therefore, if the extract contains more than400Q. ng of spl t the
p extract per th Iowing rocedu4 j. __ /
—1452.1 dd 85-90 n i ofis - boillng fla,ttu redissolve
the HEM. If necessary, heat the solution on an explosion-
proof hotplate or in a water bath to completely rediccolve the
HEM.
11.5.2.2 Transfer the extract to a 100 mL volumetric flask. Rinse the
boiling flask sequentially with 2 - 3 cnt 1l portions of n-
hexane and add to the volumetric flask. Dilute to the mark
with n-h 2ne.
11.5.2.3 Calcnlaze -the extr volume that conr.in 1000 mg of
extractable material according to the following equation:
M od l 64 22 29 March 1994 Drift
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Equation 3
1,000 V
v-
where:
V.. volume of aliquot to be withdrawn (xnL)
V total volume of solvent used in Section 11.5.2.2 (ml.)
- weight of extractable material from HEM
measur i1t (mg)
11.5.2.4 Using a calibrated pipes, r ove the volume to be withdrawn
(V) and return to the boiling flask. Dilute to approirn tely
100 ml. with n-hexane.
11.5.3 Adsorption with silica gel-Because the capacity of silica gel is not known for
all substances, it is presumed that 3 g will adsorb 100 mg of all adsorbable
materials.
.6) to the
thereof,
to a maximum of 30 g of silica gel. For 2mpIe, if the
weight of HEM is 735 mg, add3 x8 — 24g of silica gel.
11.5.3.2 Add a PTFE-coated stirring bar to the fl2 k and stir the
solution on a m2gnetic stirrer for a minimum of 5 minutes.
11.5.4 Filter the solution through n-hexane moistened filter paper into a predried,
tared boiling flask conr ining several boiling chips. Rinse the silica gel and
filter paper with several tri i11 amounts of n-hexane to complete the transfer.
113.5 Evaporate the solution and determine the weight of SGT-HEM per Sections
11.4.1 - 11.4.4.
12. DATA ANALYSIS AND CALCULATIONS
12.1 Hexane extractable material-Calcul rp the concentration of HEM (uoil and
v s ) in the sample per the following epzation
ethod 16 4
23
29 Much t994 D th
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HEM (mg/ I .) -
Equation 4
V(L)
where:
— weight of extractable material from Section 11.4.4.1 (zn&J
V 1 — sample volume from Section 11.4.5 (I.)
12.2 Silica gel treated hexane extractable material-Calculate the concentration of
SGT-HEM (petroleum hydrocarbons’) in the c ’nple per the equation above,
substituting W (from Section 11.4.4.2) for Wh. 11 the extract was split to
decrease the total amount of niiti’rial to 1,000 mg, determine the corrected
total weight of GT-HEM in the un-split extract (W) using the following
equation:
Equation 5
[ 7 1
- --wh re.
— weight in the portion of the extract split for adsorption (Sections
11.5.2.4 and 11.4.2.2).
V and V are as defined in Equation 3.
Use the corrected total weight of SGT-HEM in the un-split extract (W)to
determine the total SGT-HEM in the sample by substituting W for in
Equaton 4.
12.3 Reporting
12.3.1
Samples—Report results to three significant figures for HEM and SGT-
HEM found above the Mn”num Level (Section 1.6) in all samples.
Do not. report results below the Mirnrnum Level.
12.3.2 Report results to three signi.fltant figures for HEM and Sti1 I-th.M
found above the MDL (Sectioii 1.6)11 all sr2nrhrds (IPR, OPR) and
blanks. Do not report results below the MDL.
M hcd 1664
24
29 March 1994 Drth
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13. METHOD PERFORMANCE
This method was validated in two laboratories n ’ng spiked reagent water samples
(Refrrences 16.8 - 16.9) and treated and untreated effluents.
14. POLLUTION PREVENTION
14.1 The solvents used in this method pose little threat to the environment when recycled
and im n2ged properly.
14.2 Standards should be prepared in volumes consistent with laboratory use to nhinim,e
the volume of expired standards to be disposed.
15. WASTE MANAGEMENT
15.1 It s the laboratory’s responsibility to comply with all federal, state, and local
regulations governing waste manag nt, particularly the - h ardous waste
identificatiQn niles - -
land 1y mi, fnI7tng bench
opedti.!d aiso
required.
15.2 Samples containing HC1 to pH <2 are hazardous and must be nentralized before
being poured down a drain or must be handled as hazardous waste.
15.3 For further informaticn on waste m nigement , consult ‘The Waste Management
Manual for Laboratory Personnel,’ available from the American Ci mca1 Society’s
Department of Government Relations and Science Policy, 115 16th Street NW.,
W h; t , D.C. 20036.
16; REFERENCES
16.1. ‘Determination of the Method Detection T and Mnan um Level for EPA Oil
and Grease Method 413.1’, USEPA Office of Water, Office of Science and
Techno1ogy F ngneering and Analysis Division (4303), W chington, DC 20460,
February 18, 1994.
M-’ ’d 16 4
25
29 March 1994 Dré
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16.2 40 CPA 136, Appendix A, Methods 1624 and 1625.
16.3 ‘Carcinogens - Working With Carcinogens,’ Department of Health, Edtw inon, and
Welfare, Public Health Service, Center for Disease Control, National institute for
Occupational Safety and Health, Publication No. 77-206, August 1977.
16.4 ‘OSHA Safety and Health Sr ridards, General Industry,’ (29 CPA 1910),
Occupational Safety and Health Administration, OSHA 2206 (Revised, January
1976).
16.5 ‘Safety in Academic Chemistry Laboratories,’ American. Chemical Society,
Comr ttee on Chemical Safety, 3rd Edition, 1979.
16.6 ASTM Annual Book of Standards, Part 31, D3370 .76. ‘&andard Practices.for
Sampling Water,w American Society for Testing and Materials, Philadelphia.
16.7 Handbook.of uality. ,Control in Water and
I
EMSL-Cincinñati, OH 4526 IPA-600/4-19-019 (Mar 4aZ ).
f—I; ___
16.8 ‘Inithl-Práion and.&ccu ?acy Stud Fr g .Rep1i n nt Study, “, Global
Environmental Laboratories Inc., December 18, 1993. Available from the EPA
Sample Control Center, 300 N. Lee St., Alexandria, VA 22314.
16.9 Freon Replacement Method Study - Phase II ’, Special Analytical Services Contract
1273, Commonwealth Technology Inc., September 29, 1993. Available from the
EPA Sample Control Center, 300 N. Lee St. Alexandria, VA 22314.
M d 16 4
26
29 March 1994 Dré
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17. TABLE
Table 17.1 Acceptance Criteria for Performance Tests
Acceptance Criterion Section Lin ,it
Initial precision and recovery 9.2.1
Precision (a) 9.2.2 16 pei eL1t
Recovery (X) 9.2.2 80- 120 percent
Matrix spike/matrix spike duplicate 9.3
Recovery 9.3.4 - 75- 125 percent
RPD 9.3.5 - 20 percent
Ongoing pr cif1 ’ind recov 9.6 ‘5-
IS. GLLY RA Fl
The definitions and purposes below are specific to this method but have been
conformed so common usage as much as possible.
Analyse : The HEM or SGT-HEM tested for by this method.
Analytical batch The of samples extracted at the time, to a n ”num of
10 samples. Earh analytical batch of 10 or fewer umpl must be accompanied by
a laboratory blank (Section 9.4), an ongoing precision and recovery sample (OPR,
Section 9.6), and i matrix spike and matrix spike duplicate (MS/MSD, Section 9.3),
resu1tinginaninmoffiveanalyses(1 ’ p1e,1bl 1OPR,IMS,andI
MSD) and a m rmium of 14 analyses (10 s2rnples, 1 b1 nk . 1 OPR., I MS and I
MSD) in the b tv4i If greater than 10 samples are to be extracted at one time , the
samples m ist be separated into analytical batchet of 10 or fewer samples.
ihod 1664
27
9Mgch 994 Drth
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Field blank : An aliquot ofreagent waxer that is placed in a sample container in the
laboratory or in the field and treated as a sample in all respects, including exposure
to s ampling site conditions, storage, preservation, and all analytical procedures. The
purpose of the field blank is to determine if the field or sample transporting
procedures and environments have cont2mnlted the sample.
H!M : See Hexane extractable m irerial.
Hexane extractable material : The material that is extracted from a sample and
determined by this method.
Laboratory blank ( method blank An aliquot of reagent water that is treated exactly
as a sample including exposure to all glassware, equipment, solvents, reagents, internal
standards, and surrogates that are used with samples. The laboratory blank is used
to if analytea.or-interferences are present
(OPR)..
Matrix spike ( MS) and matrix spike duplicate ( MSD) : Aliquots of an environmental
sample to which known quantities of the analytes are “ Ided in the laboratory. The
MS and MSD are analyzed exactly like a sample. Their purpose is to quantify the
bias and precision caused by the sample matrix. The background co’wentrations of
the analytes in the sample matrix must be determined in a separate aliquot and the
measured values in the MS and MSD corrected for b kground corv entrations.
May : Th on,acuvity, r procedural step is neither required nor prohibited.
May not : This action, activity, or procedural step is prohibited.
Minimum level ( ML) : The lowest level at which the entire analytical system gives
a recogniv hle sign 1 and acceptable calibration point (Reference 16.2)
Must : This action, activity, or procedural step is required.
M d 1664
28
Z9Much 1994 Drth
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Ongoing precision and recovery standard (also called a laboratory control sample) :
A laboratory blank spiked with known quanuues of analyzes. The OPR is analyzed
exactlyllkeasample. Its pupo eis to assurethat the results produced by the
laboratory rern in within the limits specified in this method fort precision and
accuracy.
Ouality control sample (QCS) : A sample conr ’n ng HEM and/or SGT-H M at
known concentrations. The QCS is obtained from a source external to the
laboratory or is prepared from a source of standards differ from the source of
calibration standards. It is used to check laboratory performance with test materials
prepared external to the normal preparation process.
- Reagent ater Water demonstrated to be free from HEM and SGT-HEM and
povnn2lly4znerfering suhr es at the MDL of this
I F j: . ,4
SGT-HE)& See Silica n.hexaxi e mw’vM . .
rJaCdQ AtP jsLdbrnno4rei
Silica gel treated n-hexane extr ’able material : n.H. n ’ tractab1e material (HEM)
that is not adsorbed by itilic2 gel.
Stock solution A solution cont ithig an analyte that is prepared ‘ icing a reference
material traceable to EPA, the National Institute of Science and Technology (N1S ,
or a source that will attest to the purity and authenticity of the reference material.
29 i994 Drd
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