Investigation of the Source of Blank Problems in the Measurement of Lead in Sub-micrometre Airborne Particulates by Inductively Coupled Plasma Mass Spectrometry

Abstract

The development of a method for the determination of trace amounts of lead in airborne fine particulates using ICP-MS for sample analysis is described. A systematic approach to the reduction of blank readings and to the identification of sources of contamination was applied, using the techniques of factorial experimental design and multi-way analysis of variance (ANOVA). The former provides an economical method for indicating significant sources of contamination to the blank readings. The latter is a statistical method for the study of the effects of these sources and their interactions. It was found that a significant contribution of the high blank readings is attributable to the ‘memory effect’ exhibited by the laboratory PTFE-ware. As a result of this study, the detection limit of the method, in terms of the mass of lead on the filter, was reduced from 20 to 1 ng.