ASSAY OF 3-CARBOXY-ANTIPYRINE IN URINE BY CAPILLARY GAS-CHROMATOGRAPHY WITH NITROGEN SELECTIVE DETECTION - SOME PRELIMINARY-RESULTS IN MAN

An assay procedure is described for 3-carboxy-antipyrine in urine using gas chromatography with a support coated open tubular capillary column (Carbowax 20M), a solid injection system and N selective detection. 3-Carboxy-antipyrine was analyzed after derivatization with diazomethane and using 4-bromo-antipyrine as internal standard. After extraction of the urine samples with a mixture of organic solvents, linear calibration curves were obtained in the concentration range of 1-50 .mu.g/ml. Precision was established as .+-. 5.0% (no. = 5), and the lowest measurable concentration was 1 .mu.g/ml at a signal-to-noise ratio of 10:1. Preliminary results in 5 human volunteers showed that after oral administration of 500 mg antipyrine, 3.3 .+-. 0.8% of the dose was excreted as 3-carboxy-antipyrine in 52 h urine. The compound was excreted completely in the unconjugated form.