ASTM D5185 for additive elements, wear metals, contaminants and selected elements
ASTM D5185 Standard 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)
4. Summary of Test Method
4.1 A weighed portion of a thoroughly homogenized used oil is diluted tenfold by weight with mixed xylenes or other suitable solvent. Standards are prepared in the same manner. An optional internal standard can be added to the solutions to compensate for variations in test specimen introduction efficiency. The solutions are introduced to the ICP instrument by free aspiration or an optional peristaltic pump. By comparing emission intensities of elements in the test specimen with emission intensities measured with the standards, the concentrations of elements in the test specimen are calculable.
5. Significance and Use
5.1 This test method covers the rapid determination of 22 elements in used lubricating oils and in base oils, and it provides rapid screening of used oils for indications of wear. Test times approximate a few minutes per test specimen, and detectability for most elements is in the low mg/kg range. In addition, this test method covers a wide variety of metals in virgin and re-refined base oils. Twenty-two elements can be determined rapidly, with test times approximating several minutes per test specimen.
5.2 When the predominant source of additive elements in used lubricating oils is the additive package, significant differences between the concentrations of the additive elements and their respective specifications can indicate that the incorrect oil is being used. The concentrations of wear metals can be indicative of abnormal wear if there are baseline concentration data for comparison. A marked increase in boron, sodium, or potassium levels can be indicative of contamination as a result of coolant leakage in the equipment. This test method can be used to monitor equipment condition and define when corrective actions are needed.
5.3 The concentrations of metals in re-refined base oils can be indicative of the efficiency of the re-refining process. This test method can be used to determine if the base oil meets specifications with respect to metal content.
