Cathodic stripping voltammetric determination of pentamidine isethionate at a hanging mercury drop electrode

Differential-pulse cathodic stripping voltammetry was used for the determination of trace amounts of pentamidine isethionate at a hanging mercury drop electrode using its reduction peak at –1.57 V in 0.2 mol l–1 sodium hydroxide. The optimum accumulation potential and accumulation time were –1.1 V and up to 180 s, respectively. Linear calibration graphs were obtained up to 1 × 10–6 mol l–1: the limit of detection was calculated to be 3.0 × 10–10 mol l–1. The effect of various components of urine on the voltammetric response was studied, and albumin, creatinine and uric acid caused interference in the method. The direct determination of the drug (>1 × 10–7 mol l–1) in urine can be effected using a high dilution of the sample.