The Rapid Determination of Indomethacin in 50 μ1 Blood Samples

Abstract A method for the determination of indomethacin in 50 μ1 samples of rat blood by high-pressure liquid chromatography has been developed. After addition of sodium acetate buffer (pH=5.4) and an internal standard (glutethimide), the blood was extracted twice with heptane containing 1.5% (v/v) isoamyl alcohol. The organic solvent was evaporated, the residue dissolved in methanol, and aliquots (5 μl) injected automatically into the chromatograph. The separation and quantification of indomethacin was achieved on a μBondapak C18 column with 66% (v/v) methanol in water solution at a flow rate of 2 ml/min and detected at 254 nm wavelength. The analysis was linear for concentrations ranging from 0.50 to 10 μg/ml indomethacin solutions. The method was tested to determine the concentration of indomethacin in blood of rats receiving orally 2 mg/kg of indomethacin.