ASTM D7876 Standard Practice for Practice for Sample Decomposition Using Microwave Heating (With or Without Prior Ashing) for Atomic Spectroscopic Elemental Determination in Petroleum Products and Lubricants
1. Scope
1.1 This practice covers the procedure for use of microwave radiation for sample decomposition prior to elemental determination by atomic spectroscopy.
1.1.1 Although this practice is based on the use of inductively coupled plasma atomic emission spectrometry (ICP-AES) and atomic absorption spectrometry (AAS) as the primary measurement techniques, other atomic spectrometric techniques may be used if lower detection limits are required and the analytical performance criteria are achieved.

1.2 This practice is applicable to both petroleum products and lubricants such as greases, additives, lubricating oils, gasolines, and diesels.

1.3 Although not a part of Committee D02's jurisdiction, this practice is also applicable to other fossil fuel products such as coal, fly ash, coal ash, coke, and oil shale.
1.3.1 Some examples of actual use of microwave heating for elemental analysis of fossil fuel products and other materials are given in Table 1.

1.3.2 Some additional examples of ASTM methods for microwave assisted analysis in the non-fossil fuels area are included in Appendix X1.

1.4 During the sample dissolution, the samples may be decomposed with a variety of acid mixture(s). It is beyond the scope of this practice to specify appropriate acid mixtures for all possible combinations of elements present in all types of samples. But if the dissolution results in any visible insoluble material, this practice may not be applicable for the type of sample being analyzed, assuming the insoluble material contains some of the analytes of interest.

1.5 It is possible that this microwave-assisted decomposition procedure may lead to a loss of "volatile" elements such as arsenic, boron, chromium, mercury, antimony, selenium, and/or tin from the samples. Chemical species of the elements is also a concern in such dissolutions since some species may not be digested and have a different sample introduction efficiency.

1.6 A reference material or suitable NIST Standard Reference Material should be used to confirm the recovery of analytes. Ifthese are not available, the sample should be spiked with a known concentration of analyte prior to microwave digestion.

1.7 Additional information on sample preparation procedures for elemental analysis of petroleum products and lubricants can be found in Practice D7455.

1.8 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

1.9 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. Specific warning statements are given in Sections 6 and 7.

2. Referenced Documents
2.1 ASTM Standards:
C1234 Practice for Preparation of Oils and Oily Waste Samples by High-Pressure, High-Temperature Digestion for Trace Element Determinations
C1347 Practice for Preparation and Dissolution of Uranium Materials for Analysis
C1463 Practices for Dissolving Glass Containing Radioactive and Mixed Waste for Chemical and Radiochemical Analysis
D482 Test Method for Ash from Petroleum Products
D874 Test Method for Sulfated Ash from Lubricating Oils and Additives
D1193 Specification for Reagent Water
D1506 Test Methods for Carbon Black - Ash Content
D2216 Test Methods for Laboratory Determination of Water (Moisture) Content of Soil and Rock by Mass
D4057 Practice for Manual Sampling of Petroleum and Petroleum Products
D4177 Practice for Automatic Sampling of Petroleum and Petroleum Products
D4309 Practice for Sample Digestion Using Closed Vessel Microwave Heating Technique for the Determination of Total Metals in Water
D4628 Test Method for Analysis of Barium, Calcium, Magnesium, and Zinc in Unused Lubricating Oils by Atomic Absorption Spectrometry
D4643 Test Method for Determination of Water (Moisture) Content of Soil by Microwave Oven Heating
D4951 Test Method for Determination of Additive Elements in Lubricating Oils by Inductively Coupled Plasma Atomic Emission Spectrometry
D5185 Test Method for Determination of Additive Elements, Wear Metals, and Contaminants in Used Lubricating Oils and Determination of Selected Elements in Base Oils by Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES)
D5258 Practice for Acid-Extraction of Elements from Sediments Using Closed Vessel Microwave Heating
D5513 Practice for Microwave Digestion of Industrial Furnace Feedstreams and Waste for Trace Element Analysis
D5765 Practice for Solvent Extraction of Total Petroleum Hydrocarbons from Soils and Sediments Using Closed Vessel Microwave Heating
D5862 Test Method for Evaluation of Engine Oils in Two-Stroke Cycle Turbo-Supercharged 6V92TA Diesel Engine (Withdrawn 2009)
D6010 Practice for Closed Vessel Microwave Solvent Extraction of Organic Compounds from Solid Matrices
D6792 Practice for Quality System in Petroleum Products and Lubricants Testing Laboratories
D7260 Practice for Optimization, Calibration, and Validation of Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES) for Elemental Analysis of Petroleum Products and Lubricants
D7303 Test Method for Determination of Metals in Lubricating Greases by Inductively Coupled Plasma Atomic Emission Spectrometry
D7455 Practice for Sample Preparation of Petroleum and Lubricant Products for Elemental Analysis
D7740 Practice for Optimization, Calibration, and Validation of Atomic Absorption Spectrometry for Metal Analysis of Petroleum Products and Lubricants
E1358 Test Method for Determination of Moisture Content of Particulate Wood Fuels Using a Microwave Oven
E1645 Practice for Preparation of Dried Paint Samples by Hotplate or Microwave Digestion for Subsequent Lead Analysis

2.2 Other documents:
CFR 1030.10 Radiological Health
FCC Rule Part 18 Labelling Guidelines, Labelling, Information to User, Information in Manual, User Manual

3. Terminology
3.1 Definitions:
3.1.1 AAS, n - atomic absorption spectrometry, an analytical technique for measuring metal content of solutions, based on a combination of flame source, hollow cathode lamp, photomultiplier, and a readout device.

3.1.2 additive, n - a material added to another, usually in small quantities, to impart or enhance desirable properties or to suppress undesirable properties.

3.1.3 blank, n - solution which is similar in composition and contents to the sample solution but does not contain the analyte being measured.

3.1.4 certified reference material, n - a reference material one or more of whose property values are certified by a technically valid procedure, accompanied by a traceable certificate or other documentation which is issued by a certifying body.

3.1.5 dilution factor, n - ratio of the sample weight of the aliquot taken to the final diluted volume of the solution.
3.1.5.1 Discussion - The dilution factor is used to multiply the observed reading and obtain the actual concentration of the analyte in the original sample.

3.1.6 ICP-AES, n - inductively coupled plasma atomic emission spectrometry, a high temperature discharge generated by passing an ionizable gas through a magnetic field induced by a radio frequency coil surrounding the tubes that carry gas. The light emitted by excited atoms by this process is measured at fixed wavelengths specific to elements of interest and converted to their concentrations in a sample.

3.1.7 reference material (RM), n - a material with accepted reference value(s), accompanied by an uncertainty at a stated level of confidence for desired properties, which may be used for calibration or quality control purposes in the laboratory.
3.1.7.1 Discussion - Sometimes these may be prepared "in-house" provided the reference values are established using accepted standard procedures.

3.1.8 standard reference material (SRM), n - trademark for reference materials certified by National Institute of Standards and Technology.