DETERMINATION OF MOLYBDENUM IN ENGINE OIL S AND ADDITIVES BY SPECTROPHOTOMETRY AND TCP AES

In this work, conditions for the determination of molybdenum in pure a nd used motor oils are given for spectrophotometric as well as ICP AES methods. Mineralization procedures are described and the results of t he spectrophotometric determination of Mo(V) with thiocyanate, followi ng the sample mineralization with the mixture of alkaline carbonates, are compared with the results obtained by three ICP AES methods: (A) f ollowing the microwave sample mineralization, (b) after mineralization by alkalic carbonates, (c) direct Mo determination in xylene solution s. Spectrophotometric determination can be performed in the range 0.05 5-4.0 mg.l(-1) (%RSD=2.08) at 461.2 nm. ICP AES determination after mi crowave mineralization or mineralization by the carbonate mixture is p ossible in the rangs 0,.030-5.00 mg.l(-1) (%RSD being 2.26 and 2.65, r espectively), and the direct ICP AES methods is applicable in the rang e 0.041-5.00mg.l(-1) (%RSD=1.78).