Screening of β-2 agonists and confirmation of fenoterol, orciprenaline, reproterol and terbutaline with gas chromatography-mass spectrometry as tetrahydroisoquinoline derivatives

A new method for a comprehensive screening and confirmation of beta -2 agonists in human urine is presented based on gas chromatography-low-resolution mass spectrometry (GC-MS) using electron impact ionisation (EI). After hydrolysis of the conjugates with beta -glucuronidase/arylsulfatase a derivatisation step with formaldehyde converts fenoterol, orciprenaline, reproterol and terbutaline to one derivative, a tetrahydroisoquinoline, while the other beta -2 agonists remain unchanged. Liquid-liquid extraction and trimethylsilylation follow. The tetrahydroisoquinoline derivatives show good gas chromatographic and mass spectrometric behaviour. The detection limit of these four beta -2 agonists in the screening using low-resolution mass spectrometry is 10 ng/ml of urine. The other beta -2 agonists are detected as parent compounds with the same recovery after sample preparation with and without formaldehyde. The EI mass spectra of the tetrahydroisoquinoline derivatives are presented. (C) 2001 Elsevier Science B.V. All rights reserved.