Determination of antimony(III), antimony(V), and methylantimony species in natural waters by atomic absorption spectrometry with hydride generation

Abstract

The antimony species antimony(III), antimony(V), methylstlbonlc acid, and dimethylstibinlc acid are reduced In aqueous matrix by sodium borohydride to stlblne, methylstlbine, and dimethylstibine. Sb(III) and Sb(V) are reduced together to stlblne under highly acidic conditions In a solution containing Iodide. Sb(III) Is selectively reduced at near-neutral pH, where no reduction of Sb(V) takes place. Sb(V) Is then obtained by subtraction. The methylantimony acids are reduced at acid pH without addition of Iodide. The stibines are collected on a llquld-nitrogen-cooled trap and separated chromatographically after heating the trap. They elute Into a quartz cuvette burner or graphite furnace mounted In the beam of an atomic absorption spectrophotometer; the resulting absorbance signals are recorded as chromatographic peaks. The absolute detection limit is 30-60 pg of Sb, depending on species and operating conditions; the concentration limit of detection Is 0.3-0.6 ng L~1 for a 100-mL sample. Analytical results from river and estuarine waters are presented. Sb(III), Sb(V), methylstibonlc acid, and dlmethylstlbinic acid were found In natural waters. © 1981, American Chemical Society. All rights reserved.