Abstract: To determine the contents of iron, copper, nickel and magnesium in lubricating oil, lube oil samples were treated by dry ashing method and then dissolved in water to be tested by atomic absorption spectrometry. The interference of coexisting elements, silicon and etc., was investigated. Results showed that in certain concentration range the interference of silicon to the determination of iron and magnesium happened, yet it could be eliminated by the addition of lanthanum-based inhibitor. Test results for precision and accuracy showed that the relative standard deviations for these four tested elements were all less than 5%, and the recovery rates of individual elements were in the range of 96%-105%.

Key words: atomic absorption spectrometry, lubricating oil, iron, copper, nickel, magnesium