TEST SUMMARY
This test method is applicable for the determination of boron, copper, sulfur, phosphorus, calcium, magnesium, and zinc in lubricating oils and additives. Higher or lower concentrations can be determined by using additional and appropriate dilution.
A sample is weighed and then diluted with mixed xylenes or other suitable solvent on a weight-by-weight basis. Standards are prepared in the same manner. An internal standard must be added to the solutions to test for variations in sample-solution introduction. The solutions are introduced by using a peristaltic pump or free aspiration to an inductively coupled plasma (ICP) and elemental determinations are made by comparing standard and sample atomic emission intensities at wavelengths associated with the desired elements.
Significant under-recoveries are obtained when VI improvers are present in the oil sample. This has been corroborated by several oil company laboratories. To overcome this interference, dilute the sample >40 fold and use cobalt or other internal standard.
TEST PRECISION
