Determination of tetramethyl- and tetraethyllead vapours in air following collection on a glass-fibre - iodised carbon filter disc

Abstract

Methods are described for the determination of tetraalkyllead vapour in air. The related sampling procedure operates efficiently over a wide range of leading-air concentrations, flow-rates and sampling periods. It is also effective under extreme conditions of humidity, can be applied in the presence of gasoline vapour and is especially convenient for personal monitoring or for use in the field.

The air sample is passed through a glass-fibre-iodised carbon filter on which tetraalkyllead compounds are collected. Lead is then extracted from the filter and converted into the inorganic state by treatment with iodine solution, followed by colorimetric determination as lead dithizonate using a commercially available test kit. In an alternative procedure involving the use of nitric acid-bromine reagent for extraction, the lead is determined by atomic-absorption spectrophotometry with electrothermal atomisation.

The efficiency of the methods has been confirmed using laboratory prepared air samples containing 5–400 µg m^–3 of lead.