Rapid high performance liquid chromatographic determination of chlorpropamide in human plasma

Samples were extracted with dichloromethane and the organic layer evaporated to dryness. The residue was dissolved in methanol, and 25 mu l aliquot injected onto the column. Tolbutamide was used as the internal standard for chlorpropamide. The UV detector response was linear over the range 0 - 300 mu g/ml, with a correlation coefficient of 0.999 and detection limit of 1.30 ng/ ml. Within day and between-day assay variations was generally < 2.50%. No interference from endogenous constituent was observed. The utility of the method was demonstrated by determine chlorpropamide in samples from human volunteers following a single oral dose of 250 mg in drug interaction studies. The procedure is simple and fast, requiring small volumes of plasma.