A SIMPLE SPECTROPHOTOMETRIC PROCEDURE FOR THE DETERMINATION OF ANTIMONY(III) AND ANTIMONY(V) IN ANTILEISHMANIAL DRUGS

A spectrophotometric method for the selective determination of antimon y (III) and (V) in antileishmanial drugs is described. The procedure i s based on the reaction of Sb(III) with bromopyrogallol red (BPR) in n eutral solution. As a consequence of the Sb-BPR complex formed, the ab sorbance of BPR, at 560 nm, decreases proportionally to the amount of Sb(III) in the analyte solution. The calculated apparent molar absorpt ivity and determination limits are 3.67 x 10(4) L . cm(-1). mol(-1) an d 1.65 x 10(-6) mol/L, respectively. Sb(V) is determined after reducti on to Sb(III) by iodide. The Sb(V) content determined in ten samples o f Glucantime varied from 75.40 +/- 0.97 to 94.47 +/- 1.0 mg/mL. Sb(III ) was detected in all samples analyzed, and mean values ranged from 5. 19 +/- 0.16 to 10.52 +/- 0.15 mg/mL. The method is suitable for the ro utine quality control of pharmaceutical formulations.