1、Designation: D7876 13Standard Practice forPractice for Sample Decomposition Using MicrowaveHeating (With or Without Prior Ashing) for AtomicSpectroscopic Elemental Determination in PetroleumProducts and Lubricants1This standard is issued under the fixed designation D7876; the number immediately foll
2、owing the designation indicates the year oforiginal adoption 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. Scope1.1 This practice co
3、vers the procedure for use of microwaveradiation for sample decomposition prior to elemental deter-mination by atomic spectroscopy.1.1.1 Although this practice is based on the use of induc-tively coupled plasma atomic emission spectrometry (ICP-AES) and atomic absorption spectrometry (AAS) as thepri
4、mary measurement techniques, other atomic spectrometrictechniques may be used if lower detection limits are requiredand the analytical performance criteria are achieved.1.2 This practice is applicable to both petroleum productsand lubricants such as greases, additives, lubricating oils,gasolines, an
5、d diesels.1.3 Although not a part of Committee D02s jurisdiction,this practice is also applicable to other fossil fuel products suchas coal, fly ash, coal ash, coke, and oil shale.1.3.1 Some examples of actual use of microwave heating forelemental analysis of fossil fuel products and other materials
6、are given in Table 1.1.3.2 Some additional examples of ASTM methods formicrowave assisted analysis in the non-fossil fuels area areincluded in Appendix X1.1.4 During the sample dissolution, the samples may bedecomposed with a variety of acid mixture(s). It is beyond thescope of this practice to spec
7、ify appropriate acid mixtures forall possible combinations of elements present in all types ofsamples. But if the dissolution results in any visible insolublematerial, this practice may not be applicable for the type ofsample being analyzed, assuming the insoluble material con-tains some of the anal
8、ytes of interest.1.5 It is possible that this microwave-assisted decomposi-tion procedure may lead to a loss of “volatile” elements such asarsenic, boron, chromium, mercury, antimony, selenium,and/or tin from the samples. Chemical species of the elementsis also a concern in such dissolutions since s
9、ome species maynot be digested and have a different sample introductionefficiency.1.6 A reference material or suitable NIST Standard Refer-ence Material should be used to confirm the recovery ofanalytes. If these are not available, the sample should be spikedwith a known concentration of analyte pri
10、or to microwavedigestion.1.7 Additional information on sample preparation proce-dures for elemental analysis of petroleum products and lubri-cants can be found in Practice D7455.1.8 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandar
11、d.1.9 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. Specific war
12、ningstatements are given in Sections 6 and 7.2. Referenced Documents2.1 ASTM Standards:2C1234 Practice for Preparation of Oils and Oily WasteSamples by High-Pressure, High-Temperature Digestionfor Trace Element DeterminationsC1347 Practice for Preparation and Dissolution of UraniumMaterials for Anal
13、ysisC1463 Practices for Dissolving Glass Containing Radioac-tive and Mixed Waste for Chemical and RadiochemicalAnalysisD482 Test Method for Ash from Petroleum Products1This practice is under the jurisdiction of ASTM Committee D02 on PetroleumProducts and Lubricants and is the direct responsibility o
14、f Subcommittee D02.03 onElemental Analysis.Current edition approved June 15, 2013. Published August 2013. DOI: 10.1520/D7876-13.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume informatio
15、n, refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1D874 Test Method for Sulfated Ash from Lubricating Oilsand AdditivesD1193 Specification for Reagent WaterD1506 Test Met
16、hods for Carbon BlackAsh ContentD2216 Test Methods for Laboratory Determination of Water(Moisture) Content of Soil and Rock by MassD4057 Practice for Manual Sampling of Petroleum andPetroleum ProductsD4177 Practice for Automatic Sampling of Petroleum andPetroleum ProductsD4309 Practice for Sample Di
17、gestion Using Closed VesselMicrowave Heating Technique for the Determination ofTotal Metals in WaterD4628 Test Method for Analysis of Barium, Calcium,Magnesium, and Zinc in Unused Lubricating Oils byAtomic Absorption SpectrometryD4643 Test Method for Determination of Water (Moisture)Content of Soil
18、by Microwave Oven HeatingD4951 Test Method for Determination of Additive Elementsin Lubricating Oils by Inductively Coupled PlasmaAtomic Emission SpectrometryD5185 Test Method for Determination ofAdditive Elements,Wear Metals, and Contaminants in Used Lubricating Oilsand Determination of Selected El
19、ements in Base Oils byInductively Coupled Plasma Atomic Emission Spectrom-etry (ICP-AES)D5258 Practice for Acid-Extraction of Elements from Sedi-ments Using Closed Vessel Microwave HeatingD5513 Practice for Microwave Digestion of Industrial Fur-nace Feedstreams and Waste for Trace Element AnalysisD5
20、765 Practice for Solvent Extraction of Total PetroleumHydrocarbons from Soils and Sediments Using ClosedVessel Microwave HeatingD5862 Test Method for Evaluation of Engine Oils in Two-Stroke Cycle Turbo-Supercharged 6V92TA Diesel Engine(Withdrawn 2009)3D6010 Practice for Closed Vessel Microwave Solve
21、nt Ex-traction of Organic Compounds from Solid MatricesD6792 Practice for Quality System in Petroleum Productsand Lubricants Testing LaboratoriesD7260 Practice for Optimization, Calibration, and Valida-tion of Inductively Coupled Plasma-Atomic EmissionSpectrometry (ICP-AES) for Elemental Analysis of
22、 Petro-leum Products and LubricantsD7303 Test Method for Determination of Metals in Lubri-cating Greases by Inductively Coupled Plasma AtomicEmission SpectrometryD7455 Practice for Sample Preparation of Petroleum andLubricant Products for Elemental AnalysisD7740 Practice for Optimization, Calibratio
23、n, and Valida-tion of Atomic Absorption Spectrometry for Metal Analy-sis of Petroleum Products and LubricantsE1358 Test Method for Determination of Moisture Contentof Particulate Wood Fuels Using a Microwave OvenE1645 Practice for Preparation of Dried Paint Samples byHotplate or Microwave Digestion
24、for Subsequent LeadAnalysis2.2 Other documents:CFR 1030.10 Radiological HealthFCC Rule Part 18 Labelling Guidelines, Labelling, Informa-tion to User, Information in Manual, User Manual3. Terminology3.1 Definitions:3.1.1 AAS, natomic absorption spectrometry, an analyticaltechnique for measuring metal
25、 content of solutions, based on acombination of flame source, hollow cathode lamp,photomultiplier, and a readout device. D77403.1.2 additive, na material added to another, usually insmall quantities, to impart or enhance desirable properties or tosuppress undesirable properties. D58623.1.3 blank, ns
26、olution which is similar in composition andcontents to the sample solution but does not contain the analytebeing measured. D77403The last approved version of this historical standard is referenced onwww.astm.org.TABLE 1 Referenced Examples of Microwave Heating for Dissolution of Fossil Fuel and othe
27、r SamplesMaterial Element(s) Determined Measurement Technique ReferenceABiological Materials Multiple AAS and NAA Abu Samra et al (1)Biological Materials Multiple AAS and NAA Barrett et al (2)West et al (3)Geological Materials Multiple Matthes et al (4)Oil Shales Multiple ICP-AES Nadkarni (5)Coal an
28、d Fly Ash Multiple ICP-AES Nadkarni (5)Plant and Grain Standards Multiple ICP-MS Feng et al (6)Greases Multiple ICP-AES Fox (7); Nadkarni (8)Petroleum Products Multiple ICP-AES Hwang et al (9)Crude Oil Multiple ICP-MS Xie et al (10)Residual Fuel Oil Multiple ICP-MS Wondimu et al (11)Oils Lanthanides
29、 and Platinum GroupMetalsICP-MS Woodland et al (12)AAS; ICP-AES Kingston and Jassie (13)AAS; ICP-AES Kingston and Haswell (14)Soils and Sediments Lanthanides ICP-MS Ivanova et al (15)AThe boldface numbers in parentheses refer to the list of references at the end of this standard.D7876 1323.1.4 certi
30、fied reference material, na reference materialone or more of whose property values are certified by atechnically valid procedure, accompanied by a traceable cer-tificate or other documentation which is issued by a certifyingbody. D67923.1.5 dilution factor, nratio of the sample weight of thealiquot
31、taken to the final diluted volume of the solution.3.1.5.1 DiscussionThe dilution factor is used to multiplythe observed reading and obtain the actual concentration of theanalyte in the original sample. D77403.1.6 ICP-AES, ninductively coupled plasma atomicemission spectrometry, a high temperature di
32、scharge generatedby passing an ionizable gas through a magnetic field inducedby a radio frequency coil surrounding the tubes that carry gas.The light emitted by excited atoms by this process is measuredat fixed wavelengths specific to elements of interest andconverted to their concentrations in a sa
33、mple.3.1.7 reference material (RM), na material with acceptedreference value(s), accompanied by an uncertainty at a statedlevel of confidence for desired properties, which may be usedfor calibration or quality control purposes in the laboratory.3.1.7.1 DiscussionSometimes these may be prepared “in-h
34、ouse” provided the reference values are established usingaccepted standard procedures. D67923.1.8 standard reference material (SRM), ntrademark forreference materials certified by National Institute of Standardsand Technology. D77404. Summary of Practice4.1 Aweighed portion of the sample is subjecte
35、d to alternatemeans of sample dissolution which may include (optional)sulfated ashing in a muffle furnace followed by closed or openvessel microwave digestion in acid(s). Ultimately, these dilutedacid solutions are analyzed using AAS or ICP-AES. Bycomparing absorbance or emission intensities of elem
36、ents inthe test specimen with those measured of the calibrationstandards, the concentrations of elements in the test specimencan be calculated.4.1.1 The final elemental determinations can also be doneusing ICP-MS; cold vapor and hydride generation AFS/AAScan be used for mercury and hydride forming e
37、lements;however, there is no standard ASTM procedure for such workat present.4.2 Optimal conditions for microwave digestion depend onsample weight, composition, volume of digestion acidreagents, and the microwave system used.5. Significance and Use5.1 Often it is necessary to dissolve the sample, pa
38、rticularlyif it is a solid, before atomic spectroscopic measurements. It isadvantageous to use a microwave oven for dissolution of suchsamples since it is a far more rapid way of dissolving thesamples instead of using the traditional procedures of dissolv-ing the samples in acid solutions using a pr
39、essure decomposi-tion vessel, or other means.5.2 The advantage of microwave dissolution includes fasterdigestion that results from the high temperature and pressureattained inside the sealed containers. The use of closed vesselsalso makes it possible to eliminate uncontrolled trace elementlosses of
40、volatile species that are present in a sample or that areformed during sample dissolution. Volatile elements arsenic,boron, chromium, mercury, antimony, selenium, and tin maybe lost with some open vessel acid dissolution procedures.Another advantage of microwave aided dissolution is to havebetter co
41、ntrol of potential contamination in blank as comparedto open vessel procedures. This is due to less contaminationfrom laboratory environment, unclean containers, and smallerquantity of reagents used (9).5.3 Because of the differences among various makes andmodels of satisfactory devices, no detailed
42、 operating instruc-tions can be provided. Instead, the analyst should follow theinstructions provided by the manufacturer of the particulardevice.5.4 Mechanism of Microwave HeatingMicrowaves havethe capability to heat one material much more rapidly thananother since materials vary greatly in their a
43、bility to absorbmicrowaves depending upon their polarities. Microwave ovenis acting as a source of intense energy to rapidly heat thesample. However, a chemical reaction is still necessary tocomplete the dissolution of the sample into acid mixtures.Microwave heating is internal as well as external a
44、s opposed tothe conventional heating which is only external. Better contactbetween the sample particles and the acids is the key to rapiddissolution. Thus, heavy nonporous materials such as fuel oilsor coke are not as efficiently dissolved by microwave heating.Local internal heating taking place on
45、individual particles canresult in the rupture of the particles, thus exposing a freshsurface to the reagent contact. Heated dielectric liquids (water/acid) in contact with the dielectric particles generate heatorders of magnitude above the surface of a particle. This cancreate large thermal convecti
46、on currents which can agitate andsweep away the stagnant surface layers of dissolved solutionand thus, expose fresh surface to fresh solution. Simplemicrowave heating alone, however, will not break the chemicalbonds, since the proton energy is less than the strength of thechemical bond (5).5.4.1 In
47、the electromagnetic irradiation zone, the combina-tion of the acid solution and the electromagnetic radiationresults in near complete dissolution of the inorganic constitu-ents in the carbonaceous solids. Evidently, the electromagneticenergy promotes the reaction of the acid with the inorganicconsti
48、tuents thereby facilitating the dissolution of these con-stituents without destroying any of the carbonaceous material.It is believed that the electromagnetic radiation serves as asource of intense energy which rapidly heats the acid solutionand the internal as well as the external portions of thein
49、dividual particles in the slurry. This rapid and intense internalheating either facilitates the diffusion processes of the inor-ganic constituents in solution or ruptures the individual par-ticles thereby exposing additional inorganic constituents to thereactive acid. The heat generated in the aqueous liquid itselfwill vary at different points around the liquid-solid interfaceand this may create large thermal convection currents whichcan agitate and sweep away the spent acid solution containingD7876 133dissolved inorganic constituents from the surface layers of thecarbo
