Acid-soluble membrane filter for the pre-concentration and electrothermal atomisation atomic absorption spectrometric determination of trace levels of cadmium in water

Abstract

An acid-soluble membrane filter is proposed for the simple and rapid pre-concentration of trace levels of cadmium in water. Cadmium is collected on a nitrocellulose membrane filter as the 1-(2-pyridylazo)-2-naphthol (PAN) complex by filtration under suction and the complex is then dissolved in 0.5 ml of warm concentrated sulphuric acid together with the membrane filter. After addition of 1.0 ml of water to reduce the viscosity of the concentrate, the cadmium is determined by electrothermal atomisation atomic absorption spectrometry. High concentrations of sodium chloride, calcium, magnesium, sulphate and bromide and sub mg l^–1 levels of zinc(II), iron(III), manganese (II) and copper(II) do not interfere in the determination. The detection limit is 1.5 ng l^–1 of cadmium at the 3σ_B level. The proposed technique was applied to the analysis of river and sea water samples.