High performance liquid chromatography electrochemical detection applied to monitoring clopamide in human urine and pharmaceutical formulations

A simple and sensitive HPLC-EC method has been developed for the determination of the benzothiazidic diuretic 4-Chloro-N-(2,6-dimethylpiperidino)-3-sulphamoylbenzamide (Clopamide), using a mu Bondapack C18 column with a mobile phase of acetonitrile-water (35:65) containing 5mM sodium acetate/acetic acid at a flow rate of 1mL/min. After a simple alkaline liquid-liquid extraction procedure with ethyl acetate, clopamide can be extracted from urine with percentages of recovery greater than 95%. The compound can be detected and measured with good reproducibility and an experimental quantitation limit of 20 ng/mL at a positive potential of + 1400 mV. Clopamide has been determined in the pharmaceutical formulation Brinerdine (clopamide 10 mg, reserpine 0.1 mg, dihydroergotoxine mesilate 0.58 mg and tartrazine 0.064 mg). The method developed has been also applied to the determination of clopamide in human urine samples obtained at different time intervals after the ingestion of a single dose of Brinerdine.