1.1This practice covers the procedure for use of microwave radiation for sample decomposition prior to elemental determination by atomic spectroscopy.
1.1.1Although 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.
1.2This practice is applicable to both petroleum products and lubricants such as greases, additives, lubricating oils, gasolines, and diesels.
1.3Although 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.
1.3.1Some examples of actual use of microwave heating for elemental analysis of fossil fuel products and other materials are given in Table 1.
TABLE 1 Referenced Examples of Microwave Heating for Dissolution of Fossil Fuel and other Samples
Material | Element(s) Determined | Measurement Technique | ReferenceA |
Biological 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 and 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 and Platinum Group Metals | ICP-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) |
1.3.2Some additional examples of ASTM methods for microwave assisted analysis in the non-fossil fuels area are included in Appendix X1.
1.4During 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.
1.5It 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.
1.6A reference material or suitable NIST Standard Reference Material should be used to confirm the recovery of analytes. If these are not available, the sample should be spiked with a known concentration of analyte prior to microwave digestion.
1.7Additional information on sample preparation procedures for elemental analysis of petroleum products and lubricants can be found in Practice D7455.
1.8The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.9This 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.