Antipyrine, indocyanine green, and lorazepam determined in plasma by high-pressure liquid chromatography.

This HPLC method for measuring antipyrine, lorazepam, and indocyanine green in 0.5 mL of plasma can be used in studies of liver function in which these "model" compounds are used. After a fast, simple, one-step extraction procedure with acetonitrile, an isocratic HPLC system is used, with a single detection wavelength (214 nm) and a single internal standard (1-acetamidopyrene). The mobile phase is a 47/53 (by vol) mixture of acetonitrile and 50 mmol/L phosphate buffer, pH 6. The three compounds are separated on an LC-18 reversed-phase column. The low cost of the HPLC method makes feasible the routine clinical measurement of all three compounds.