ASTM D3650-93(1999)

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An American National Standard
Designation: D 3650 – 93 (Reapproved 1999)
Standard Test Method for
Comparison of Waterborne Petroleum Oils By
Fluorescence Analysis
This standard is issued under the fixed designation D 3650; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope* D 3325 Practice for Preservation of Waterborne Oil
Samples
1.1 This test method covers the comparison of waterborne
D 3326 Practices for Preparation of Samples for Identifica-
petroleum oils with oils from possible sources by means of
2 tion of Waterborne Oils
fluorescence spectroscopy (1). Useful references for this test
D 3328 Test Methods for Comparison of Waterborne Petro-
methodinclude:(2)and(3)forfluorescenceanalysisingeneral
leum Oils by Gas Chromatography
and (4), (5), and (6) for oil spill identification including
D 3414 Test Method for Comparison of Waterborne Petro-
fluorescence.
leum Oils by Infrared Spectroscopy
1.2 This test method is applicable to crude or refined
D 3415 Practice for Identification of Waterborne Oils
petroleum products, for any sample of neat oil, waterborne oil,
D 4489 Practices for Sampling of Waterborne Oils
or sample of oil-soaked material. Unless the samples are
E 131 Terminology Relating to Molecular Spectroscopy
collected soon after the spill occurs, it is not recommended that
E 275 Practice for Describing and Measuring Performance
volatile fuels such as gasoline, kerosine, and No. 1 fuel oils be
of Ultraviolet, Visible, and Near Infrared Spectrophotom-
analyzed by this test method, because their fluorescence
eters
signatures change rapidly with weathering. Some No. 2 fuel
E 520 Practice for Describing Detectors in Emission and
oils and light crude oils may only be identifiable up to 2 days
Absorption Spectroscopy
weathering,orless,dependingontheseverityofweathering.In
general, samples weathered up to 1 week may be identified,
3. Terminology
although longer periods of weathering may be tolerated for
3.1 Definitions—For definitions of terms used in this test
heavy residual oils, oil weathered under Arctic conditions, or
method refer to Terminology D 1129, Practice D 3415, and
oil that has been protected from weathering by collecting in a
Terminology E 131.
thick layer.
1.3 This standard does not purport to address all of the
4. Summary of Test Method
safety problems, if any, associated with its use. It is the
4.1 This test method consists of fluorescence analyses of
responsibility of the user of this standard to establish appro-
dilute solutions of oil in spectroquality cyclohexane. In most
priate safety and health practices and determine the applica-
cases the emission spectra, with excitation at 254 nm, over the
bility of regulatory limitations prior to use.
spectral range from 280 to 500 nm, are adequate for matching.
2. Referenced Documents 4.2 Identification of the sample is made by direct visual
comparison of the sample’s spectrum with the spectra from
2.1 ASTM Standards:
3 possible source samples.
D 1129 Terminology Relating to Water
D 1193 Specification for Reagent Water
NOTE 1—When weathering has occurred, it may be necessary to
D1796 TestMethodforWaterandSedimentinFuelOilsby consider known weathering trends when matching spectra (Fig. 1 and Fig.
2).
the Centrifuge Method (Laboratory Procedure)
5. Significance and Use
This test method is under the jurisdiction of ASTM Committee D19 on Water
5.1 This test method is useful for rapid identification of
andisthedirectresponsibilityofSubcommitteeD19.06onMethodsforAnalysisfor
waterborne petroleum oil samples as well as oil samples
Organic Substances in Water.
Current edition approved May 15, 1993. Published July 1993. Originally
published as D3650 – 78. Last previous edition D3650 – 90.
The boldface numbers in parentheses refer to the references at the end of this
test method. Annual Book of ASTM Standards, Vol 11.02.
3 6
Annual Book of ASTM Standards, Vol 11.01. Annual Book of ASTM Standards, Vol 14.01.
4 7
Annual Book of ASTM Standards, Vol 05.01. Annual Book of ASTM Standards, Vol 03.06.
*A Summary of Changes section appears at the end of this standard.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D 3650 – 93 (1999)
6.3 Possible interferences from Raman or RayleighTyndall
scattering are not observed in the emission scan ranges
selected.
7. Apparatus
7.1 Fluorescence Spectrophotometer (or Spectro-
fluorometer)—An instrument recording in the spectral range of
220 nm to at least 600 nm for both excitation and emission
responses and capable of meeting the specifications stated in
Table 1.
7.2 Excitation Source—A high-pressure xenon lamp (a
150-W xenon lamp has proven acceptable). Other continuum
sources, such as deuterium or high-pressure xenon-mercury,
FIG. 1 Fluorescence Spectra for a Typical No. 2 Fuel Oil
which have sufficient intensity in the ultraviolet region, could
(Unweathered and Weathered One Day)
be used as excitation sources.
NOTE 4—Line sources such as a low-pressure mercury lamp may also
be used for excitation at 254 nm, if the flexibility of using arbitrary
excitation wavelengths or excitation spectra is not desired and if source
intensity is adequate.
7.3 Fluorescence Cells—Standard cells, made from
fluorescence-free fused silica with a pathlength of 10 mm and
a height of 45 mm.
7.4 Recorder or Computer—Strip chart or X-Y recorder,
with a response time less than 1 s for full-scale deflection, or a
computer capable of digitizing the data at a rate of 1 data point
per nanometre.
7.5 Cell-Filling Device—Disposable Pasteur capillary pi-
pet.
7.6 Volumetric Flasks—Low-actinic glass, ground-glass
FIG. 2 Fluorescence Spectra for a Typical No. 6 Fuel Oil
stoppered volumetric flasks (100-mL).
(Unweathered and Weathered One Day)
7.7 Micropipet, 10 to 50-µL capacity.
7.8 AnalyticalBalance,withaprecisionofatleast 60.1mg.
obtained from fuel or storage tanks, or from sand, vegetation,
7.9 Weighing Pans, 5 to 7-mm diameter, 18 mm deep, made
or other substrates.This test method is applicable to weathered
of aluminum or equivalent.
and unweathered neat oil samples.
7.10 Test Tubes, disposable 15-mL glass test tubes.
5.2 Theunknownoilisidentifiedthroughthecomparisonof
the fluorescence spectrum of the oil with the spectra (obtained
at similar instrumental settings on the same instrument) of
TABLE 1 Specifications for Fluorescence Spectrophotometers
possible source samples. A match of the entire spectrum
Wavelength Reproducibility
between the unknown and possible source sample indicates a
Excitation monochromator better than62nm
common source.
Emission monochromator better than 62nm
Gratings (Typical Values)
6. Interferences
Excitation monochromator minimum of 600 lines/mm blazed at
A
300 nm
6.1 The fluorescence spectrum will be distorted if an oil
Emission monochromator minimum of 600 lines/mm blazed at
A
sample has been contaminated by an appreciable amount, for 300 nm or 500 nm
example, 1 % of common chemical impurities such as other
B
Photomultiplier Tube
oils that are fluorescent on excitation at 254 nm.
C D E
Either S-20 or S-5 Response
NOTE 2—Storage of samples in improper containers (for example,
plastics) may result in contamination. This interference can be eliminated
Resolution
by observing proper procedures for collection and preservation of
Excitation monochromator better than 2 nm
samples. Refer to Practice D 3325. Emission monchromator better than 2 nm
NOTE 3—“Spectroquality” cyclohexane may not have a low enough
Time Constant
fluorescence solvent blank. Lots vary in the content of fluorescent
impurities, which may increase with storage time even if the bottle is
not to exceed one second
unopened.
A
Or designed to have a good efficiency in this spectral region.
B
6.2 Oil residues may build up in fluorescence cells particu- See Practice E 520.
C
Photomultiplier tubes such as Hamamatsu R-446-UR.
larly after prolonged usage with heavy oils. In such a case,
D
Photomultiplier tubes such as RCA 1P28 or Hamamatsu R-106.
follow the procedure using nitric acid for cleaning glassware E
Or equivalent having a good spectral response in the spectral region from 280
(10.1.3). to 600 nm.
D 3650 – 93 (1999)
7.11 Micropipet, or microsyringe, 9-µL capacity; with an 9.4 Preparation of Solutions for Fluorescence Analysis—
accuracy of 1 % and reproducibility of 0.1 % of pipet capacity. Either of the following techniques for diluting the prepared oil
7.12 Micropipet, 200-µLcapacity with disposable tips; with sample with cyclohexane may be used:
an accuracy of 1 % and reproducibility of 0.1 % of pipettor
9.4.1 Weighing Technique—To prepare oil solutions at a
capacity.
concentration of approximately 20 µg/mL, weigh out 0.0016 6
7.13 Solvent Dispenser, adjustable to deliver 10 mL.
0.0001 g of oil (equivalent weight for each sample) onto a
7.14 Vortex Mixer.
clean aluminum weighing pan using a micropipet. Transfer
weighed oil sample into a clean 100 mL, low-actinic glass
8. Reagents and Materials
volumetric flask by creasing the aluminum pan and washing
the oil directly into the volumetric flask using spectroquality
8.1 Purity of Reagents—Spectroquality grade reagents
cyclohexane dispensed from a TFE-fluorocarbon wash bottle.
should be used in all instances unless otherwise stated. It is
Dilute the solution up to volume (100 mL) and shake vigor-
intended that all reagents shall conform to the specifications of
ouslyseveraltimesandallowthepreparedsolutiontostandfor
theCommitteeonAnalyticalReagentsoftheAmericanChemi-
30 min and shake again prior to performing the analysis to
cal Society, where such specifications are available.
ensure that all oil dissolves. Occasionally, depending on
8.2 Purity of Water— References to water shall be under-
fluorescence yield of the oil tested and instrumentation used, it
stood to mean Type IV reagent water conforming to Specifi-
maybenecessarytouse100ppmconcentrationtogetadequate
cation D 1193. However, since fluorescent organic impurities
fluorescence intensity. In these cases, weigh out 0.0078 6
in the water may constitute an interference, the purity of the
water should be checked by running a water blank using the 0.0001 g of oil and proceed as above.
same instrument conditions as for the solvent blank.
NOTE 7—It is preferable that the prepared solution be used the same
8.3 Acetone (CH COCH ).
3 3
day. Do not use solutions that have been standing for periods in excess of
8.4 Nitric Acid (sp gr 1.42)—Concentrated nitric acid
6 h unless they have been refrigerated. In no case use solutions more than
(HNO ).
2 days old.
8.5 Cyclohexane, spectroquality grade, with a fluorescence
9.4.2 Volume Technique—Allow the prepared oil sample to
solvent blank less than 2 % of the intensity of the major peak
come to room temperature and shake until they are homoge-
of the sample fluorescence generated with the same instrumen-
neous.Transfer 9 µLof the oil to a 15-mLdisposable glass test
tal settings over the emission range used. Cyclohexane is
tube with a micropipet or microsyringe and add 10 mL of
dispensed throughout the procedure from a 500-mL TFE-
spectroquality cyclohexane with a solvent dispenser. Place a
fluorocarbon wash bottle. For prolonged storage, cyclohexane
capofaluminumfoiloverthetopofthetesttubeandvortexfor
should be stored only in glass. Check the suitability of the
approximately 30 s. With a micropipet, transfer 200 µL of this
solvent by running a solvent blank. The solvent blank can also
solution to a second 15-mL test tube and then add 10 mL of
be used to check for scatter.
cyclohexane. Place a cap of aluminum foil over the top of the
NOTE 5—Cyclohexane can be reused, if necessary, after one or more
second test tube and vortex for approximately 30 s. Prepare all
distillations in an all-glass still. The distilled cyclohexane must have no
samples in this manner.
detectable fluorescence (<2 %) in the 280 to 500-nm region of the
spectrum when excited at 254 nm.
NOTE 8—If a micropipet with disposable plunger and tips is used,
NOTE 6—Methylcyclohexane can also be used as a solvent, instead of
potential cross contamination is avoided. Otherwise, careful cleaning
cyclohexane. This is useful, particularly if the solution is needed for
following the procedures specified in 10.1 is required.
low-temperature luminescence measurements as well.
10. Preparation of Apparatus
8.6 Aluminum Foil.
10.1 Cleaning Glassware:
9. Sampling and Sample Preparation
10.1.1 Clean all glassware used in this procedure in the
9.1 Collect a representative sample as directed in Practice
following manner: first rinse volumetric flasks and cells three
D 4489.
times with spectroquality cyclohexane. Prior to the use of
9.2 Preserve samples in containers as specified in Practice
glassware and cells throughout this procedure, rinse again with
D 3325. However, to avoid dewaxing, do not cool samples
spectroquality cyclohexane.
below 5°C.
10.1.2 If there is water present, rinse the glassware three
9.3 Preparation of Oil Samples, as described in Practices
times with spectroquality acetone, and then three times with
D 3326. Avoid the use of deasphalting procedures, if possible.
cyclohexaneasin10.1.1.Usedetergentsonlyiftheyhavebeen
Spectroquality cyclohexane is the preferred solvent for sample
checked for low fluorescence. If laboratory detergent solutions
preparation for fluorescence.
are used, repeated rinsing with Type IV reagent (see 8.3) water
will be required.
10.1.3 When working with heavy oils, a cleaning procedure
using organic solvents may not be sufficient. Heavy oils build
“Reagent Chemicals,American Chemical Society Specifications,”Am. Chemi-
cal Soc., Washington, DC. For suggestions on the testing of reagents not listed by
up a residue on cells that solvent cleaning will not remove. If
theAmerican Chemical Society, see “Analar Standards for Laboratory Chemicals,”
the solvent blank shows significant impurities, a residual film
BDH Ltd., Poole, Dorset, U.K., and the “United States Pharmacopeia.”
on the cell, rather than an impure solvent, may be the cause.
Matheson Coleman/Bell (MC/B Cx2285) cyclohexane has given acceptable
solvent blanks or an equivalent solvent may be used. Soak the cells in undiluted nitric acid for 1 h. Observe proper
D 3650 – 93 (1999)
safety precautions by using adequate eye and hand protection. comparing the oil spectra: (1) general shape, ( 2) number of
RinsethecellsrepeatedlywithTypeIVreag
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