Selected ion monitoring of metoprolol and two metabolites in plasma and urine using deuterated internal standards

✍ Scribed by Magnar Ervik; Kurt-Jürgen Hoffmann; Kerstin Kylberg-Hanssen

• Publisher: John Wiley and Sons
• Year: 1981
• Tongue: English
• Weight: 476 KB
• Volume: 8
• Category: Article
• ISSN: 1076-5174
• DOI: 10.1002/bms.1200080708

✦ Synopsis

A highly sensitive and specific quantitative assay for metoprolol and two of its metabolites, containing an unchanged 2-hydroxy-4-isopropylaminopropoxy sidechain, has been developed. The compounds are isolated from the alkalized sample (plasma or urine) by extraction with dichloromethane, and converted to trifluoroacetyl derivatives by reaction with methyl-bis-(trifluoroacetamide). The reaction mixture is gas chromatographed on an OV-17 column and each substance is assayed by electron impact mass spectrometry using selected ion monitoring, and quantified by comparing the intensity of fragment ion m/r 266 with the intensities of corresponding fragment ions from the deuterated internal standards (mlz 270 and 271). It is possible to determine concentrations as low as 1 nmol I-' (0.3 ng m1-l) in 1 ml of sample with a relative standard deviation of less than 10%. Abbreviations: MBTFA = methyl-bis-(trifluoroacetamide); NMIM = N-methyl imidazole.

Quantiiative analyses were performed on a Varian MAT gas chromatograph mass. spectrometer system