The micro gas-liquid chromatographic analysis of 4-(3′,3′-dimethylallyl)-1,2-diphenylpyrazolidine-3,5-dione (feprazone) in human biosamples

Abstract

A gas-liquid chromatographic method for the determination of feprazone in various biological matrixes, employing a choice of detector options, is described. After rapid, micro-scale extraction of the sample with n-butyl acetate at physiological pH, the solution was injected directly onto the chromatograph. Separation was with either an OV7 column and flame ionisation or electron capture detection, or with a carbowax high polymer column and nitrogen specific detection. When 100 μl of plasma was extracted the limit of accurate measurement was 2 mg 1 −1 for F.I.D. and N.P.D. and 0.5 mg 1 −1 with E.C. detection. Quantification was by comparison with a range of plasma calibrators carried throughout the procedure, and determination of peak height ratios against an internal standard incorporated into the extracting solvent. The CV of the assay throughout the concentration range normally encountered in patients undergoing feprazone treatment, ranged between 2.4 and 7.8% for the various detector options. The analytical method has been applied to samples collected both from patients and normal volunteers undergoing treatment with a range of feprazone maintenance doses.