Significance and Use
Crude oil, petroleum, petroleum products, additives, biofuels, and lubricants are routinely analyzed for their elemental content such as chlorine, nitrogen, hydrogen, phosphorus, sulfur, and various metals using a variety of analytical techniques. Some of these methods require little to no method calibration; some others require only simple one step calibration; while others require elaborate calibration routine before the product is analyzed for its elemental content.
Fairly often it can be shown that the round robin results by a co-operator are all biased with respect to those from other laboratories. Presumably, the failure to follow good laboratory practices and instructions in the test methods can be a causal factor of such errors. A further consequence is an unnecessarily large reproducibility estimate or the data being dropped from the study as an outlier.
Another cause of such discrepancies could be different or inadequate calibration practice used in the laboratory. Most test methods spell out the calibration requirements but often do not quote the frequency required letting the laboratories use good laboratory practices for this task. Thus, uniform practice for instrument calibration would be beneficial in standardizing the test procedures and obtaining consistent results across the laboratories.
Committee D02 has already issued standard practices for uniform sample preparation (D7455), standard operating procedures for ICP-AES (D7260) and XRF (D7343) as well as standard quality assurance protocol (D6792). This guide should be considered as a continuing effort on behalf of this subcommittee to achieve standardized practices in all parts of an analytical sequence.
Scope
1.1 This guide covers different ways by which the test methods used for elemental analysis of petroleum product and lubricant samples are calibrated before the sample analysis.
1.2 Uniform practice for test method calibration is beneficial in standardizing the procedures, and obtaining consistent results across different laboratories.
1.3 This guide includes only the basic steps for generally encountered instrument types. Anything out of the ordinary may require special procedures. See individual test methods for instructions to handle such situations.
1.4 This guide is not a substitute for a thorough understanding of the actual test method to be used, caveats it contains, and additional instrument preparation that may be required.
1.5 The user should not expand the scope of the test methods to materials or concentrations outside the scope of the test methods being used.
1.6 This guide should also be applicable to sample preparation of non-petroleum based bio-fuels for elemental analysis. Work is underway on these aspects in Subcommittee D02.03. As more information becomes available, it will be added to this standard.
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.
