title: Direct derivatization of alprenolol and its 4-hydroxy metabolite in urine with phosgene and methanol prior to analysis by capillary column gas chromatography.
abstract: A method for the determination of alprenolol and its 4-hydroxy metabolite has been developed. The urine sample is made alkaline with buffer (pH 12) and derivatized with 60 microliter of 2 M phosgene in toluene with vigorous shaking. In the presence of 2.5% methanol, an oxazolidineone methyl carbonate is formed from 4-hydroxy alprenolol. The now neutral derivatives are extracted with an equal volume of dichloromethane. After evaporation of the organic phase, the residue is taken up in a small volume of ethyl acetate and subjected to capillary column gas chromatography with CP-Sil 8 as the stationary phase. The precision was 2.1% at the 3.3 micrograms/ml level of the metabolite in urine (n = 8). The isopentylamino analogue was used as the internal standard.
mesh_terms: D000526:Alprenolol / Q000031:analogs & derivatives* / Q000097:blood / Q000652:urine*; D055598:Chemical Phenomena; D002621:Chemistry; D002849:Chromatography, Gas; D006801:Humans; D007202:Indicators and Reagents; D013058:Mass Spectrometry; D000432:Methanol; D010705:Phosgene
chemical_list: D007202:Indicators and Reagents; D010705:Phosgene; C048019:4-hydroxyalprenolol; D000526:Alprenolol; D000432:Methanol