INVESTIGATION OF THE SOURCE OF BLANK PROBLEMS IN THE MEASUREMENT OF LEAD IN SUBMICROMETER AIRBORNE-PARTICULATES BY INDUCTIVELY-COUPLED PLASMA-MASS SPECTROMETRY

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 a nd to the identification of sources of contamination was applied, usin g the techniques of factorial experimental design and multi-may analys is of variance (ANOVA), The former provides an economical method for i ndicating significant sources of contamination to the blank readings. The latter isa statistical method for the study of the effects of thes e sources and their interactions, It was found that a significant cont ribution of the high blank readings is attributable to the 'memory eff ect' 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 th e filter, was reduced from 20 to 1 ng.