Determination of Wear Metals in Used Lubricating Oils by Atomic Absorption Spectrometry.

Abstract

Traces (0 to 100 p.p.m.) of copper, chromium, iron, lead, and silver in used lubricating oil can be determined by atomic absorption measurement of solutions of the oil in 2-methyl-4pentanone. Calibrating solutions are prepared by dissolving commercially available organo-metallic compounds in 2-methyl-4-pentanone containing the appropriate concentration of unused oil. The results agree satisfactorily with those obtained by atomic absorption or colorimetric measurement of solutions of the ashed specimens, and the technique is in routine use for the determination of these metals in the used lubricating oil from railway diesel engines.

Determination of Wear Metals in Lubrication Oils: A Comparison Study of ICP-OES and FAAS

“…One reason could be the fear of a possibly unstable or even dangerously intense flame. However, Burrows et al 1 tested kerosene as a dilution solvent with lubricating oils with FAAS analysis already in 1965. They observed that kerosene did not disturb the air-acetylene flame, but the sensitivity of the determination was not as good as with 2-methyl-4-pentanone.…”

“…The method's drawbacks are high sample consumption, narrow linear determination range and difficulties in determining refractory elements. [1][2][3][4][5][6][7][8][9] However, these are seldom of interest to maintenance personnel (except phosphorus, which is an important additive element in lubrication oils).…”

“…MIBK, DIBK, alcohols, xylene and naphtholite, among others, have been used with FAAS. 1,2,5,9 Xylene and kerosene are often used with ICP-OES. 14,15 When organic solvents are used, calibration standards must be made from organo-metallic substances.…”

Wear Metal Analysis of Oils

“…In 1965, Burrows et al (15) compared different organic solvents in the analysis of lubricating oils by FAAS. Heptane, kerosene and methylisobutylketone (MIBK) were included in the study.…”

“…The ash is dissolved with a suitable acid, or a mixture of different acids, and analyzed by a chosen technique. Burrows et al (15) used 10-20 g of oil in the ashing stage, but the amount of oil sample required is a lot smaller (2-5 g) in the more recent studies. Goncalves et al (33) used a method in which the treatment of an oil sample of 5 g took over five hours.…”