A HPLC method has been used to quantify plasma rifampicin and isoniazid and pyrazinamide simultaneously. Extraction of rifampicin in plasma samples was done as follows: mix 1ml of plasma containing rifampicin and 1.5 ml acetonitril on a vortex mixer for 1 minute prior to centrifugation at 3500 rpm for 30 minutes. The organic layer was filtered through 0.45m filter membrane and then 30l of this solution was injected into the HPLC system. The chromatographic conditions were as follows: in stationary phase: column: Apollo Alltech RP18 (250 x 4.6 mm; 5 m); in mobile phase: methanol - phosphate buffet solution containing 0.02M potassium dihydrogen phosphate adjusted to pH 4.5 by adding phosphoric acid (65: 35); Flow rate: 1.0 ml/min and UV detector: 254 nm
Chromatography, High Pressure Liquid ; lasma ; Pyrazinamide ; Isoniazid ; Rifampin