Significance and Use
5.1 Petroleum products may contain elements either in trace concentrations (for example, ng/g (ppb mass)) or in minor to major levels (ppm to mass %). These elements might be characteristic of the crude petroleum or might originate from specific inclusions of additives for beneficial effect in the refined product. Often, such additives have product specifications which control the quality of a product in commerce. Hence, it is important to determine these elements as accurately as possible. Other elements present at trace levels may be harmful to combustion engines causing wear or reduced performance, may cause poisoning of catalysts, or may be of environmental concern as combustion emissions. ICP-MS instrumentation is well-suited for determining these elements and is particularly useful for the determination of the trace level elements that may not be readily achieved by other techniques.
5.2 Various elemental analytical techniques such as atomic absorption spectrometry (AAS), for example, Test Method D3605 and D4628; inductively coupled plasma atomic emission spectrometry (ICP-AES), for example, Test Methods D7111, D4951, and D5185; X-ray fluorescence (XRF), for example, Practice D7343, Test Method D7220, Test Methods D4927, and Test Method D6443; or graphite furnace atomic absorption spectrometry (GFAAS), for example, Test Method D6732 are used for this purpose. This test method is the first example where ICP-MS is used for elemental analysis of petroleum products.
5.3 This test method covers the rapid determination of seven elements in distillate petroleum products. Test times approximate a few minutes per test specimen, and quantification for most elements is in the low to sub ng/g (ppb mass) range. High analysis sensitivity can be achieved for some elements that are difficult to determine by other techniques.
Scope
1.1 This test method describes the procedure for the determination of trace elements in light and middle distillate petroleum products using inductively coupled plasma mass spectrometry (ICP-MS).
1.2 This test method should be used by analysts experienced in the use of inductively coupled plasma mass spectrometry (ICP-MS) with knowledge of interpretation of spectral, isobaric, polyatomic, and matrix interferences, as well as procedures for their correction or reduction.
1.3 The table in 6.1 lists elements for which the test method applies along with recommended isotope. Actual working detection limits are sample dependent and, as the sample matrix varies, these detection limits may also vary.
1.4 The concentration range of this test method is typically from low to sub ng/g (ppb mass) to 1000 ng/g (ppb mass), however the precision and bias statement is specified for a smaller concentration range based on test samples analyzed in the ILS, see the table in Section 18. The test method may be used for concentrations outside of this range; however, the precision statements may not be applicable.
1.4.1 This test method shall be further developed to extend that table to include additional elements.
1.5 This test method uses metallo-organic standards (organometallic or organosoluble metal complex) for calibration and does not purport to quantitatively determine insoluble particulates. Analytical results are particle size dependent, and low results are obtained for particles larger than a few micrometers as these particles may settle out in the sample container and are not effectively transported through the sample introduction system.
1.6 Elements present at concentrations above the upper limit of the calibration curves can be determined with additional, appropriate dilutions and with no degradation of precision.
1.7 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.8 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 8.2, 8.7, and Section 9.
1.9 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
