Flow inejction amperometric determination of some toxic metals at low levels in aqueous solutions

ABSTRACT

Copper [II], iron [III], antimony [V] and arsenic [V] were determined as bromine, which is liberated through the reaction of the metal ions with acidic bromide solution by flow injection amperometry at a platinum electrode by injecting the sample into an eluent KBr in H2SO4 for both Cu [II] and Fe [III], or KBr in HCl for both Sb [V] and As [V]. The rectilinearity range is from 10-3 to 10-7 M. Antimony [III] and arsenic [III], that can be oxidized by bromine, were determined on-line by injecting the acidic solutions of the samples into bromate-bromide eluent and observing the decrease in the bromine signal. The determination was also performed by injecting a pre- reacted solution of bromide and Sb [V] or As [V] and monitoring the bromine produced. The method have been applied successfully to commercial tablet forms [for iron], alloys [for copper] or in the bulk powders [iron, antimony and arsenic]. The results obtained were compared statistically with those given by the titrimetric methods: