DETERMINATION OF WEAR-METALS IN USED LUBRICATING OILS FROM MARINE ENGINES BY FLAME ATOMIC-ABSORPTION SPECTROMETRY

A method for the determination of the total content of Fe, Cu, Pb and Cr in used lubricating oils from marine engines by flame atomic absorption spectrometry is described. The influence of the sample basicity, the addition of acids, and dilution with different solvents was studied. The presence of solid species which cause serious problems concerning reproducibility was also investigated. The procedure involves the use of mineral acid to dissolve the metal particles, and a mixture of isobutyl methyl ketone and a non-ionic surfactant as solvent. The standards were prepared with aqueous inorganic salt solutions. The method is rapid and shows good sensitivity and reproducibility. A comparison is made between the results obtained from the proposed procedure and those from other atomic absorption methods.