Modified extraction procedure for the spectrophotometric determination of trace amounts of aluminium in sea water with pyrocatechol violet and removal of excess of reagent

Abstract

Aluminium in sea water was determined spectrophotometrically with solvent extraction using pyrocatechol violet. The ion associate between the aluminium-pyrocatechol violet complex and zephiramine (tetradecyldimethylbenzylammonium chloride) was extracted into chloroform, and the excess of reagent co-extracted was removed by back-washing using 0.25 M sodium bromide solution (pH 9.5). The method is sensitive (apparent molar absorptivity = 9.8 × 10⁴ l mol^–1 cm^–1), selective and precise (relative standard deviation less than 4%).