Determination of ibuprofen in human plasma and urine by gas chromatography/mass spectrometry.

This paper describes a GC/MS method for the determination of ibuprofen in human plasma and urine. Ibuprofen and internal standard naproxen were extracted from plasma and urine by using a liquid-liquid extraction method. Derivatization was carried out using N-methyl-N-(trimethylsilyl) trifluoroacetamide. Calibration curves were linear over the concentration range of 0.05-5.0 and 0.1-10.0 microg/mL for plasma and urine, respectively. Intraday and interday precision (RSD) values for ibuprofen in plasma and urine were less than 6.31%, and accuracy (relative error) was better than 12.00%. The mean recovery of ibuprofen was 89.53% for plasma and 93.73% for urine. The LOD was 0.015 and 0.03 microg/mL and the LOQ was 0.05 and 0.1 microg/mL for plasma and urine, respectively. The method was successfully applied to blood samples from three healthy male volunteers who had been given an oral tablet of 600 mg ibuprofen.