Use of a cadmium-new cadion-emulsifier OP complex for the spectrophotometric determination of available cadmium in acidic soils

Abstract

A simple, rapid and sensitive spectrophotometric method for determining cadmium has been developed on the basis of a study of the colour reaction of cadmium with new cadion in the presence of emulsifier OP. The coloured complex with an absorption maximum at 520 nm is formed at pH 9.34–10.80. The calibration graph is linear from 0 to 4 µg of cadmium per 25 ml and the molar absorptivity is 1.64 × 10⁵ l mol^–1 cm^–1. The molar ratio of Cd²⁺ to new cadion in the complex was established as 1 : 2. Cadmium in soil samples can be concentrated and separated from interfering ions by extraction with isobutyl methyl ketone.

Results obtained by applying the proposed method to acidic soil samples agree well with those obtained by atomic absorption spectrophotometry.