Rigaku ZSX Primus sequential WDXRF spectrometer for lubricating oil analysis

Rigaku Corporation has announced an application report on the Rigaku ZSX Primus sequential WDXRF spectrometer. Application Note #5003 demonstrates quantitative analysis of lubricating oil in accordance with ASTM method D6443-04.

The functional properties of lubricating oil for specific purposes are established by mixing additives with base oil. Controlling the concentrations of additive elements is fundamental in lubricating oil production plants. XRF spectrometry is used for quantitative analysis of additive elements such as magnesium, phosphorus and zinc in lubricating oil because of its high precision and simple sample preparation requirements. In the XRF analysis of lubricating oil, a sample is simply poured into a liquid cell. No complicated treatment, such as chemical decomposition or dilution, is required.

The analysis is carried out on the ZSX Primus WDXRF spectrometer, which is optimised for routine analyses commonly performed by petroleum laboratories. The spectrometer was equipped with a 3 kW Rh-target X-ray tube. A 4 kW X-ray tube can be mounted if higher sensitivity or precision is required. The operation software is designed for ease of use in routine analyses, guiding users through establishing calibrations. The calibration curves were generated with matrix corrections applied for all analytes except for magnesium, as indicated in ASTM D6443-04.

The results confirm that lubricating oil can be routinely analysed with high accuracy and precision on the product with a 3 kW X-ray tube and that the performance of the instrument meets the requirements of ASTM D6443-04. The ZSX Primus also can be applied to the standard method of ASTM D4927-05, which covers higher concentration ranges of additive elements in lubricating oil.