ASTM D7751-16(R2021) pdf free download

ASTM D7751-16(R2021) pdf free download.Standard Test Method for Determination of Additive Elements in Lubricating Oils by EDXRF Analysis
1. Scope
1.1 This test method covers the quantitative determination of additive elements in unused lubricating oils and additive packages, as shown in Table 1. 1.2 Additive packages require dilution with a contamination free diluent (base oil) prior to analysis. The dilution factor has to be calculated from the expected concentrations to bring the concentrations for all elements into the ranges listed in Table 1. 1.3 Some lubrication oils will contain higher concentrations than the maximum concentrations listed in Table 1. These samples require dilution with a contamination free diluent (base oil) prior to analysis. The dilution factor has to be calculated from the expected concentrations to bring the concentrations for all elements into the ranges listed in Table 1. 1.4 This test method is limited to the use of energy dispersive X-ray fluorescence (EDXRF) spectrometers em- ploying an X-ray tube for excitation in conjunction with the ability to separate the signals of adjacent elements by using a high resolution semiconductor detector. 1.5 This test method uses inter-element correction factors calculated from a fundamental parameters (FP) approach or from another matrix correction method. 1.6 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.6.1 The preferred concentration units are mg/kg or mass %. 1.7 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 appro- priate safety, health, and environmental practices and deter- mine the applicability ofregulatory limitations prior to use. 1.8 This international standard was developed in accor- dance with internationally recognized principles on standard- ization established in the Decision on Principles for the Development of International Standards, Guides and Recom- mendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
4. Summary of Test Method
4.1 A specimen is placed in the X-ray beam, and the appropriate regions of its spectrum are measured to give the fluorescent intensities of magnesium, phosphorus, sulfur, chlorine, calcium, zinc, and molybdenum. Other regions of the spectrum are measured to compensate for matrix variation. To optimize the sensitivity for each element or group of elements, a combination ofoptimized excitation and detection conditions (for example, different primary beam filters (7.1.3), secondary or polarization targets (7.1.4), and so forth) may be used. The measuring time should be kept as short as possible, typically under 10 min per specimen. Avoid using different measurement conditions that yield only marginally better results for a specific analyte. There may be a correction of measured intensities for spectral overlap. 4.1.1 Concentrations of the elements of interest are deter- mined by comparison of these intensities against a calibration curve using a fundamental parameters (FP) approach, possibly combined with corrections from backscatter. The FP approach uses the physical processes forming the basis of X-ray fluo- rescence emission in order to provide a theoretical model for the correction of matrix effects. The correction term is calcu- lated from first principle expressions derived from basic physical principles and contain physical constants and param- eters that include absorption coefficients, fluorescence yield, primary spectral distribution and spectrometry geometry. The calculation of concentrations in samples is based on making successively better estimates of composition by an iteration procedure. N OTE 1—The algorithm used for the procedure is usually implemented in the instrument manufacturer’s software. 4.2 The EDXRF spectrometer is initially calibrated using a set of standards to collect the necessary intensity data. Each calibration line and any correction coefficient are obtained by a regression of this data, using the program supplied with the spectrometer. (Warning—Exposure to excessive quantities of X-radiation is injurious to health. The operator needs to take appropriate actions to avoid exposing any part of their body, not only to primary X-rays, but also to secondary or scattered radiation that might be present. The X-ray spectrometer should be operated in accordance with the regulations governing the use of ionizing radiation.)