Off-line Speciation of Sb(III) and Total Sb in Pharmaceuticals by Spectrophotometric Flow-injection Hydride Generation Using the Potassium Dichromate Reaction

Abstract

A spectrophotometric procedure based on flow injection analysis is proposed for Sb(III) and total Sb determination in pharmaceuticals. Sb(III) reacts with the hydrogen radical generated in the system, forming antimony hydride. The species formed is then transported towards the flow system and permeates through a Teflon interface, being carried by a constant air flow. Then, a K2Cr2O7 solution in acidic medium is added by confluence, allowing the reduction of Cr(VI) to Cr(III) and the indirect determination of Sb at 610 nm. The proposed methodology presents a linear range from 200 to 1000 mg L (r > 0.997; n = 5), 70 mg L as limit of quantification of and an analytical frequency of 40 h. The precision, expressed as RSD (n = 13 to 500 mg L Sb(III) solution), is < 5.0%. The accuracy for Sb(III) was checked through recovery tests and ranged from 96 to 105%. For total Sb, the accuracy was checked by atomic absorption spectrometry and the results are in agreement at the 95% confidence level, using the t test. Pharmaceutical samples were analyzed and an average value of 5.39 and 110 mg mL for Sb(III) and total Sb concentrations, respectively, were obtained.