Green approaches to determine metals in lubricating oils by electrothermal atomic absorption spectrometry (ETAAS)

Two simple, fast and green procedures based on sample emulsification were developed to determine V, Ni, Cu, Cr, Pb, Mo and Ag by ETAAS in used lubricating oils; they will be termed emulsion and three-component solution. Reagent consumption and residues got reduced dramatically as solutions were prepared directly in 1 mL autosampler cups. The emulsions were stable enough to perform the overall analysis without intermediate agitation between replicates. Quantitation was performed using aqueous standards and the standard additions method, except for Cu and Cr when the three-component solutions were employed. The preparation time for the two methods was 15 min/emulsion and 30 min/5 three-component solutions. Method validation was carried out with three reference materials: SRM 1084a Wear-Metals in Lubricating Oil, LO-010698 Lubricating Oil and Used Oil HU-1. The three-component solutions procedure was selected and applied to analyse several used lubricating oils. (c) 2013 Elsevier B.V. All rights reserved.