DETECTION OF SOME SULFUR ANIONS AND COLLOIDAL SULFUR BY FLAME MOLECULAR-EMISSION SPECTROMETRY

A simple flow-injection method was used to compare the disulphur emission from sulphite, thiosulphate, sulphide, thiocyanate, diethyldithiocarbamate and colloidal sulphur with that of sulphate. Counter ions were replaced with hydronium through the use of an in-line ion-exchange column. All the compounds conformed to the second-order calibration relationship already established for sulphate, but with higher emission efficiencies. The estimated detection limits range from 0.1 to 0.8 mg s l-1. The effect on the emission efficiencies of decomposition of the sulphur acids was investigated by comparison with the corresponding ammonium forms. Ammonium ions enhance the disulphur emission, in contrast to the well established depressive interference from metal cations.