Screening of beta-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 agon ists in human urine is presented based on gas chromatography-low-resolution mass spectrometry (GC-MS) using electron impact ionisation (EI). After hyd rolysis of the conjugates with beta -glucuronidase/arylsulfatase a derivati sation step with formaldehyde converts fenoterol, orciprenaline, reproterol and terbutaline to one derivative, a tetrahydroisoquinoline, while the oth er beta -2 agonists remain unchanged. Liquid-liquid extraction and trimethy lsilylation follow. The tetrahydroisoquinoline derivatives show good gas ch romatographic and mass spectrometric behaviour. The detection limit of thes e four beta -2 agonists in the screening using low-resolution mass spectrom etry is 10 ng/ml of urine. The other beta -2 agonists are detected as paren t compounds with the same recovery after sample preparation with and withou t formaldehyde. The EI mass spectra of the tetrahydroisoquinoline derivativ es are presented. (C) 2001 Elsevier Science B.V. All rights reserved.