DETERMINATION OF NIFLUMIC ACID IN HUMAN URINE BY GAS-CHROMATOGRAPHY NEGATIVE CHEMICAL-IONIZATION MASS-SPECTROMETRY

A sensitive method has been developed for the detection and determinat ion of niflumic acid (NA) in human urine. Samples were extracted with diethylether. Flunixin (FN) was added to the sample prior to extractio n as an internal standard. Niflumic acid was converted to its methyl d erivative and analyzed by capillary gas chromatography/negative chemic al ionization mass spectrometry. Using selected ion monitoring (SIM), the levels of NA down to 5 pg/ml could be detected in 5 mi spiked urin e sample. Calibration curve was linear over the range of 0.5 ppm-50 pp m. The recovery of niflumic acid from urine at 40 pg/ml was to be 91.7 +/-3.8(n=3) and the coefficient of variation was 4.1%.