Camphor-3-thioxo-2-oxime as an analytical reagent for extractive spectrophotometric determination and separation of lead

Abstract

Camphor-3-thioxo-2-oxime (HCTO) is proposed as a new sensitive analytical reagent for the extractive spectrophotometric determination of trace amounts of lead. The method is based on the instantaneous formation of a stable yellow-orange colored 1:2 chelate with lead at room temperature in the pH range 9.3–9.6 selectively extracted in carbon tetrachloride. The extracted species exhibits an absorption maximum at 400 nm with a molar absorptivity of 4.14×10 4 mol −1 cm −1, complying with Beer’s law over the concentration range 0.1–0.5 μg ml -1 of lead with an optimum concentration range 0.18–0.37 μg ml −1. The effects of pH, concentration of reagent and salting-out agents, time of equilibration, order of addition of diluents and the tolerance limit of the method towards various cations and anions usually associated with lead are reported. The developed method is successfully used for the determination of traces of lead in synthetic mixtures, alloys and ore samples.