Chemical vapour generation of silver: reduced palladium as permanent reaction modifier for enhanced performance

Abstract

Permanent modification of the surface of a continuous flow system by reduced metals was studied for chemical vapour generation (CVG) of silver. Both nickel and palladium were found to be active, but only palladium has sufficient stability and chemical resistance for routine use. Single introduction of the modifier to the CVG system is sufficient to avoid long conditioning periods following cleaning and to achieve permanent stabilization of the sensitivity for Ag at a value 3–4-fold higher than in a clean system prior to modification. A possible mechanism responsible for improvement is proposed: the modifier catalyzes the reaction of residual NaBH₄ in the reaction mixture, necessary for the final phases of volatile compound formation and/or its release from solution.