MEASUREMENT OF PLASMA IBUPROFEN BY GAS-CHROMATOGRAPHY MASS-SPECTROMETRY

A gas-chromatography-mass spectrometry (GC-MS) method for the determin ation of plasma ibuprofen was developed. Plasma samples from cystic fi brosis (CF) patients receiving high-dose ibuprofen therapy were analyz ed by GC-MS and the result compared to analysis by high-performance li quid chromatography (reference method). Analysis of ibuprofen was sens itive to at least 5 mg/L, and the method was linear to 200 mg/L. Withi n-run variations of plasma samples were 4.6% (131.7 +/- 6.0 mg/L) and 5.4% (44.4 +/- 2.4 mg/L), respectively. The between-run variation was 9.3% (45.4 +/- 4.2 mg/L) and 7.4% (88.0 +/- 6.5 mg/L). This method is suited for routine clinical use for the monitoring of plasma ibuprofen levels in treatment of CF. It may be particularly applicable in pedia tric laboratories, which are likely to possess GC-MS capability. (C) 1 997 Wiley-Liss, Inc.