TOXICOLOGICAL DETECTION OF IBUPROFEN AND ITS METABOLITES IN URINE USING GAS-CHROMATOGRAPHY MASS-SPECTROMETRY (GC-MS)

Ibuprofen, (R,S)-2-(4-isobutylphenyl)propionic acid, is a non-opioid a nalgesic which is prescription-free available in pharmacies since 1989 . Consequently, use and misuse of this analgesic strongly increased. F or diagnosis of an abuse or an intoxication a GC-MS procedure was deve loped for the toxicological detection of ibuprofen in urine after extr action at pH 5 and methylation. For screening, mass chromatography wit h the masses m/z 220, 161 (methylated ibuprofen), 178, 119 (methylated hydroxy ibuprofen) and 264, 145 (methylated carboxy ibuprofen) was us ed to indicate the presence of these compounds in urine. The identity of the peaks underlying full mass spectra was confirmed by comparison with the reference spectra using computer library search. After ingest ion of one single oral dose of 400 mg ibuprofen, the parent compound c ould be detected for 27 to 34 h, hydroxy ibuprofen for 34 to 40 h and carboxy ibuprofen for 5 to 6 d. Using this procedure ibuprofen which w as taken even several days ago could be detected.