1、Designation: D7691 111D7691 16Standard Test Method forMultielement Analysis of Crude Oils Using InductivelyCoupled Plasma Atomic Emission Spectrometry (ICP-AES)1This standard is issued under the fixed designation D7691; the number immediately following the designation indicates the year oforiginal a
2、doption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1 NOTEAppendix X2 was editorially corrected in August 2014.1. Scope Scope*1.1 Thi
3、s test method covers the determination of several elements (including iron, nickel, sulfur, and vanadium) occurring incrude oils.1.2 For analysis of any element using wavelengths below 190 nm, 190 nm, a vacuum or inert gas optical path is required.1.3 Analysis for elements such as arsenic, selenium,
4、 or sulfur in whole crude oil may be difficult by this test method due to thepresence of their volatile compounds of these elements in crude oil; but this test method should work for resid samples.1.4 Because of the particulates present in crude oil samples, if they do not dissolve in the organic so
5、lvents used or if they donot get aspirated in the nebulizer, low elemental values may result, particularly for iron and sodium. This can also occur if theelements are associated with water which can drop out of the solution when diluted with solvent.1.4.1 An alternative in such cases is using Test M
6、ethod D5708, Procedure B, which involves wet decomposition of the oilsample and measurement by ICP-AES for nickel, vanadium, and iron, or Test Method D5863, Procedure A, which also uses wetacid decomposition and determines vanadium, nickel, iron, and sodium using atomic absorption spectrometry.1.4.2
7、 From ASTM Interlaboratory Crosscheck Programs (ILCP) on crude oils data available so far, it is not clear that organicsolvent dilution techniques would necessarily give lower results than those obtained using acid decomposition techniques.21.4.3 It is also possible that, particularly in the case of
8、 silicon, low results may be obtained irrespective of whether organicdilution or acid decomposition is utilized. Silicones are present as oil field additives and can be lost in ashing. Silicates should beretained but unless hydrofluoric acid or alkali fusion is used for sample dissolution, they may
9、not be accounted for.1.5 This test method uses oil-soluble metals for calibration and does not purport to quantitatively determine insolubleparticulates. Analytical results are particle size dependent and low results may be obtained for particles larger than a fewmicrometers.1.6 The precision in Sec
10、tion 18 defines the concentration ranges covered in the interlaboratory study. However, lower andparticularly higher concentrations can be determined by this test method. The low concentration limits are dependent on thesensitivity of the ICP instrument and the dilution factor used. The high concent
11、ration limits are determined by the product of themaximum concentration defined by the calibration curve and the sample dilution factor.1.7 Elements present at concentrations above the upper limit of the calibration curves can be determined with additionalappropriate dilutions and with no degradatio
12、n of precision.1.8 As a generality based on this interlaboratory study (see 18.1), the trace elements identifiable in crude oils can be dividedinto three categories:1.8.1 Element levels that are too low for valid detection by ICP-AES and hence, cannot be determined: aluminum, barium, lead,magnesium,
13、 manganese, and silicon.1.8.2 Elements that are just at the detection levels of the ICP-AES method and hence, cannot be determined with a great dealof confidence: boron, calcium, chromium, copper, molybdenum, phosphorus, potassium, sodium, and zinc. Perhaps thedetermination of these elements can be
14、considered as semi-quantitative.1 This test method is under the jurisdiction ofASTM Committee D02 on Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of SubcommitteeD02.03 on Elemental Analysis.Current edition approved Jan. 1, 2011June 1, 2016. Published February 201
15、1June 2016. Originally approved in 2011. Last previous edition approved in 2011 asD7961 111. DOI: 10.1520/D769111E01.10.1520/D7691-16.2 Nadkarni, R. A., Hwang, J. D., and Young, L., “Multielement Analysis of Crude Oils Using Inductively Coupled Plasma Atomic Emission Spectrometry,” J. ASTMInternatio
16、nal, Vol 8, No. 10, 2011, pp. 103837.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM re
17、commends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box
18、C700, West Conshohocken, PA 19428-2959. United States11.8.3 Elements that are at higher levels of concentration and can be determined with good precision: iron, nickel, sulfur, andvanadium.1.9 The detection limits for elements not determined by this test method follow. This information should serve
19、as an indicationas to what elements are not present above the detection limits typically obtainable by ICP-AES instruments.D7691 162Element mg/kgAluminum 1Barium 0.2Boron 1Calcium 0.1Chromium 0.1Copper 0.1Lead 1.4Magnesium 1Manganese 0.1Molybdenum 0.2Phosphorous 1Potassium 0.5Silicon 4Zinc 0.51.10 T
20、his test method determines all possible elements simultaneously and is a simpler alternative to Test Methods D5184,D5708, or D5863.1.11 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.12 This standard does not purport to add
21、ress all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:3C1109 Practice
22、for Analysis of Aqueous Leachates from Nuclear Waste Materials Using Inductively Coupled Plasma-AtomicEmission SpectroscopyD1552 Test Method for Sulfur in Petroleum Products by High Temperature Combustion and IR DetectionD4057 Practice for Manual Sampling of Petroleum and Petroleum ProductsD4177 Pra
23、ctice for Automatic Sampling of Petroleum and Petroleum ProductsD4307 Practice for Preparation of Liquid Blends for Use as Analytical StandardsD5184 Test Methods for Determination of Aluminum and Silicon in Fuel Oils by Ashing, Fusion, Inductively Coupled PlasmaAtomic Emission Spectrometry, and Atom
24、ic Absorption SpectrometryD5185 Test Method for Multielement Determination of Used and Unused Lubricating Oils and Base Oils by InductivelyCoupled Plasma Atomic Emission Spectrometry (ICP-AES)D5708 Test Methods for Determination of Nickel, Vanadium, and Iron in Crude Oils and Residual Fuels by Induc
25、tively CoupledPlasma (ICP) Atomic Emission SpectrometryD5854 Practice for Mixing and Handling of Liquid Samples of Petroleum and Petroleum ProductsD5863 Test Methods for Determination of Nickel, Vanadium, Iron, and Sodium in Crude Oils and Residual Fuels by FlameAtomic Absorption SpectrometryD6299 P
26、ractice for Applying Statistical Quality Assurance and Control Charting Techniques to Evaluate Analytical Measure-ment System PerformanceD6792 Practice for Quality System in Petroleum Products and Lubricants Testing LaboratoriesD7260 Practice for Optimization, Calibration, and Validation of Inductiv
27、ely Coupled Plasma-Atomic Emission Spectrometry(ICP-AES) for Elemental Analysis of Petroleum Products and LubricantsE135 Terminology Relating to Analytical Chemistry for Metals, Ores, and Related Materials3. Terminology3.1 For the definition of emission spectroscopy, refer to Terminology E135.3.2 De
28、finitions of Terms Specific to This Standard:3.2.1 analyte, nelement whose concentration is being determined.3.2.2 Babington-type nebulizer, ndevice that generates an aerosol by flowing a liquid over a surface that contains an orificefrom which gas flows at a high velocity.3.2.3 calibration, nproces
29、s by which the relationship between signal intensity and elemental concentration is determined fora specific element analysis.3.2.4 calibration curve, nplot of signal intensity versus elemental concentration using data obtained by making measurementswith standards.3 For referencedASTM standards, vis
30、it theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.D7691 1633.2.5 detection limit, nconcentration of an analyte that results in a signal intensity
31、that is some multiple (typically two) timesthe standard deviation of the background intensity at the measurement wavelength.3.2.6 inductively-coupled plasma (ICP), nhigh-temperature discharge generated by flowing an ionizable gas through amagnetic field induced by a load coil that surrounds the tube
32、s carrying the gas.3.2.7 linear response range, nelemental concentration range over which the calibration curve is a straight line, within theprecision of the test method.3.2.8 profiling, ntechnique that determines the wavelength for which the signal intensity measured for a particular analyte isa m
33、aximum.3.2.9 radio frequency (RF), nrange of frequencies between the audio and infrared ranges (3(3 GHz to 300 GHz).300 GHz).4. Summary of Test Method4.1 This test method usually requires several minutes per sample. A weighed portion of a thoroughly homogenized crude oilis diluted tenfold by weight
34、with mixed xylenes, kerosene, or other suitable solvent. Standards are prepared in the same manner.A mandatory internal standard is added to the solutions to compensate for variations in test specimen introduction efficiency. Thesolutions are introduced to the ICP instrument by a peristaltic pump. B
35、y comparing emission intensities of elements in the testspecimen with emission intensities measured with the standards, the concentrations of elements in the test specimen are calculable.5. Significance and Use5.1 Most often determined trace elements in crude oils are nickel and vanadium, which are
36、usually the most abundant; however,as many as 45 elements in crude oils have been reported. Knowledge of trace elements in crude oil is important because they canhave an adverse effect on petroleum refining and product quality. These effects can include catalyst poisoning in the refinery andexcessiv
37、e atmospheric emission in combustion of fuels.Trace element concentrations are also useful in correlating production fromdifferent wells and horizons in a field. Elements such as iron, arsenic, and lead are catalyst poisons. Vanadium compounds cancause refractory damage in furnaces, and sodium compo
38、unds have been found to cause superficial fusion on fire brick. Someorganometallic compounds are volatile which can lead to the contamination of distillate fractions, and a reduction in their stabilityor malfunctions of equipment when they are combusted.5.2 The value of crude oil can be determined,
39、in part, by the concentrations of nickel, vanadium, and iron.5.3 Inductively coupled plasma-atomic emission spectrometry (ICP-AES) is a widely used technique in the oil industry. Itsadvantages over traditional atomic absorption spectrometry (AAS) include greater sensitivity, freedom from molecularin
40、terferences, wide dynamic range, and multi-element capability. See Practice D7260.6. Interferences6.1 SpectralThere are no known spectral interferences between elements covered by this test method when using the spectrallines listed in Table 1. However, if spectral interferences exist because of oth
41、er interfering elements or selection of other spectrallines, correct for the interference using the technique described in Test Method D5185.TABLE 1 Elements Determined and Suggested WavelengthsAElement Wavelength, nmAluminum 308.215, 396.153, 309.271, 237.01Barium 233.53, 455.403, 493.410Boron 249.
42、773, 182.59, 249.68Calcium 315.887, 317.933, 364.44, 422.67Chromium 205.552, 267.716, 298.92, 283.563Copper 324.754, 219.226Iron 259.94, 238.204, 271.44, 259.837Lead 220.353, 224.688, 283.306Magnesium 279.079, 279.553, 285.21, 293.65Manganese 257.61, 293.31, 293.93, 294.92Molybdenum 202.03, 281.616,
43、 204.598, 203.844Nickel 231.604, 227.02, 221.648, 341.476Phosphorus 177.51, 178.289, 214.914, 253.40Potassium 766.491, 769.896Sodium 588.995, 330.29, 589.3, 589.592Silicon 288.159, 251.611, 212.412, 282.851Sulfur 180.731, 182.04, 182.62Vanadium 292.403, 309.31, 310.23, 311.07Zinc 202.551, 206.209, 2
44、13.856, 334.58, 481.05, 202.48A These wavelengths are only suggested and do not represent all possiblechoices. Not all of these elements were determined in this interlaboratory study.D7691 1646.2 Check all spectral interferences expected from the elements listed in Table 1. Follow the manufacturers
45、operating guide todevelop and apply correction factors to compensate for the interferences. To apply interference corrections, all concentrations shallbe within the previously established linear response range of each element listed in Table 1. (WarningCorrect profiling isimportant to reveal spectra
46、l interferences from high concentrations of some elements on the spectral lines used for determiningtrace metals.)6.2.1 Spectral interferences can usually be avoided by judicious choice of analytical wavelengths. When spectral interferencescannot be avoided, the necessary corrections should be made
47、using the computer software supplied by the instrument manufactureror the empirical method described below. Details of the empirical method are given in Test Method C1109 and by Boumans.4 Thisempirical correction method cannot be used with scanning spectrometer systems when both the analytical and i
48、nterfering linescannot be located precisely and reproducibly. With any instrument, the analyst shall always be alert to the possible presence ofunexpected elements producing interfering spectral lines.6.2.2 The empirical method of spectral interference correction uses interference correction factors
49、. These factors are determinedby analyzing the single-element, high purity solutions under conditions matching as closely as possible those used for test specimenanalysis. Unless plasma conditions can be accurately reproduced from day to day, or for longer periods, interference correctionfactors found to affect the results significantly shall be redetermined each time specimens are analyzed.6.2.3 Interference correction factors can be negative if off-peak background correction is employed for element, i. A negativeKia correction factor can result when an inter
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