Lead atomisation from soil by slurry introduction electrothermal atomisation atomic absorption spectrometry. Part 2. Atomisation characteristics with various matrix modifiers

Abstract

Lead atomic absorption signals were obtained from a model soil matrix (montmorillonite and humic acid) introduced into a graphite furnace as slurry particles. The effects of various matrix modifiers on the absorbance-peak characteristics were studied. This provided information on probable atomisation processes and mechanisms of matrix modification. Several soils were analysed and the modifiers Mg, phosphate, a Mg-phosphate mixture, Pd and a Mg-Pd mixture were all effective. The Mg-Pd mixture was the most suitable, because it produced similar absorbance appearance and peak maximum times for the slurries and aqueous calibration standards. Other matrix modification methods (making the slurry in 1% HNO₃, O₂ ashing and pre-slurry ashing in a muffle furnace) were less suitable, because the Pb atomisation characteristics differed from those of aqueous standards.