Haematoxylin with quaternary ammonium salts as spectrophotometric reagents for tin(IV)
Haematoxylin with cetyltrimethylammonium bromide (CTAB) is proposed for the spectrophotometric determination of tin(IV). The addition of CTAB improved the colour reaction of tin(IV) with haematoxylin, resulting in better sensitivity and a longer linear range of the calibration graph. Similar results were obtained with cetyldimethylbenzylammonium chloride and cetylpyridinium bromide. Oxidised haematoxylin is not a suitable reagent for tin(IV) because of its poor stability in solution.