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Adsorptive stripping Voltammetric determination of irbesartan using a hanging mercury drop electrode (HMDE) is described. The method is based on adsorptive accumulation of the species at the HMDE, followed by a first-harmonic alternating current (AC) stripping sweep at pH 6. The behavior of the adsorptive stripping response was studied under various experimental conditions, e.g., type of supporting electrolyte, pH, accumulation time, scan rate, and mode of sweep. In Britton-Robinson buffer solution, a quasi-reversible reduction process involving transfer of two electrons and two protons takes place. The response was linear over the concentration range of 0.16 -1.60 mg/ml with regression coefficient 0.997 and detection limit 0.11 mg/ml. The average of determinations of the cited compound in oral dosages with its standard deviation was 99.39 ± 4.33 %.The result obtained by the proposed method was compared with that obtained by the uv-spectrophotometric technique. Furthermore, the proposed method was also successfully applied as a stability-indicating method.

Cathodic stripping voltammetric determination of losartan using hanging mercury drop electrode HMDE was described. The method was based on adsorptive accumulation of the species at HMDE and at pH 7, followed by alternating current AC sweep. The behavior of adsorptive stripping response was studied under various experimental conditions, e.g. type of supporting electrolyte, pH, accumulation time, scan rate and mode of sweep (direct current DC, differential pulse DP, square wave SW and AC). In Britton-Robinson buffer solution, pH 7, a quasi-reversible reaction took place. The reduction response was more sensitive than the oxidation one and it was linear over the concentration range of 0.16-1.2 µg/mL. The determination of the cited compound in oral dosages was achieved using the standard addition method. The average of determinations obtained by square wave adsorptive voltammetric method with its standard deviation was 100.1±3%.

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The electrochemical behavior of antibiotic drugs, clindamycin hydrochloride (I) and its phosphate salt (II), on carbon paste electrode (CPE) is thoroughly investigated. Chemical and electrical parameters affecting the adsorption stripping voltammetry (ASV) measurements are optimized. Two different modes of sweep, viz., differential pulse (DP) and square wave (SW), are compared over a potential range of +400 to +1100 mV in the presence of 0.04 M Britton -Robinson buffer (pH 10) with an accumulation time of 30 s, scan rate of 100 mV/s, and pulse amplitude of 30 mV. The responses are linear over a concentration range of 86 -430 and 90 -813 ng/ml for I and 86 -516 and 172 -1030 ng/ml for II in the DP and SW sweep modes, respectively. The limits of detection (with correlation coefficients given in brackets) are as follow (ng/ml): 32.60 (0.998) and 90.73 (0.994) for I and 43.51 (0.997) and 83.02 (0.996) for II in the DP and SW sweep modes, respectively. The DP method has been applied successfully to determining the active ingredients in pharmaceutical preparations and in spiked urine with mean percentage recoveries of 99.24 ± 2.14 and 98.66 ± 2.38, respectively.