Atom formation processes in the presence of thiourea in electrothermal atomic absorption spectrometry with a molybdenum microtube atomizer

Abstract

The processes of atom formation of antimony, bismuth, cadmium, copper and silver atomized in the presence of thiourea in a molybdenum microtube atomizer are discussed. These elements form complexes with thiourea and are converted to their sulfides during the charring stage. Atomization in argon—hydrogen occurs by reduction of the metal sulfide by hydrogen followed by vaporization of the free metal, or by thermal dissociation of the metal sulfide. Atom formation processes in pure argon are somewhat different. The activation energies for bismuth, cadmium and copper atomization are unaltered in a chloride matrix, provided that thiourea is present.