ELIMINATION OF HYDROFLUORIC-ACID INTERFERENCE IN THE DETERMINATION OFANTIMONY BY THE HYDRIDE GENERATION TECHNIQUE

For the determination of antimony by hydride generation techniques a p retreatment procedure has been developed for the reduction of Sb(V) to Sb(III) in order to remove the effect of hydrofluoric acid which stro ngly interferes with the reduction of pentavalent antimony to the triv alent state. It is based on the combined action of L-cysteine and bori c acid at 80 degrees C. The pretreatment is effective in both nitric a nd hydrochloric acid media. Quantitative recoveries are obtained in le ss than 60 min. Under these conditions antimony is reduced to the triv alent state in acid media containing both nitric and hydrochloric acid . The method has been applied to the determination of total antimony i n certified reference materials of sediments after pressurized microwa ve digestion with HNO3-HCl-HF. Good agreement is obtained by using bot h analytical techniques: continuous flow hydride generation atomic flu orescence spectrometry and flow injection electrothermal atomic absorp tion spectrometry with in-situ trapping of stibine in a graphite atomi zer. (C) 1998 Elsevier Science B.V.