Determination of 2,4-diamino-5-(3,4-dichlorophenyl)-6-methylpyrimidine (BW 197U) in human plasma.

A gas-liquid chromatographic method for the measurement of 2,4-diamino-5-(3,4-dichlorophenyl)-6-methylpyrimidine (BW 197U) in human plasma has been developed. After extraction from alkaline medium into ethyl acetate the compound is injected into a gas-liquid chromatograph and measured using a 63Ni constant-current electron-capture detector. The range of concentrations measured was from 10 ng/ml to 10 microgram/ml in plasma. An internal standard was employed and reproducibility between replicates was found to be good. The method has been semi-automated by the use of an auto-sampler controlled by a minicomputer which also processes the data.