Comparison of plumbane and tetraethyllead for the determination of lead by inductively coupled plasma atomic emission spectrometry

Abstract

Continuous flow generation of two different types of volatile lead species, PbH 4 (NaBH 4 as the reducing agent) or tetraethyllead (NaBEt 4 as the alkylating agent) as a means of gaseous sample introduction for inductively coupled plasma atomic emission spectrometry (ICP-AES) have been investigated in detail. The advantages of both compounds for sample introduction are critically compared in terms of sensitivity, selectivity and accuracy for the determination of low levels of lead by ICP-AES. Lead determination by ICP-AES using NaBH 4 in a medium of potassium dichromate and lactic acid as oxidant/complexing acid system provided a detection limit of 2 ng ml −1 lead with a relative standard deviation (R.S.D.) of 1.3% at the 50 ng ml −1 level ( n = 10) and good selectivity. NaBEt 4 used as reducing agent in the same reaction medium provided a detection limit of 1 ng ml −1, an R.S.D. of 1.2% at the 50 ng ml −1 level ( n = 10) and even better selectivity. Both methods have been applied to the determination of low levels of lead by ICP-AES in vegetables and sediments. The results obtained show good agreement with certified or expected values.