Abstract: A method has been developed for the determination of 23 β2-agonists and 5 β-blockers in urine samples using high performance liquid chromatography-ion trap mass spectrometry (HPLC-IT-MS). Urine samples were first deproteinized by high-speed frozen centrifugation, and the supernatants were loaded on an ExtrelutTM diatomite column for clean-up. The analytes were eluted by ethyl acetate and concentrated for further analysis. The analytical separation was performed on an AtlantisT3-150 mm chromatographic column with the gradient elution using methanol and water (containing 0.1% formic acid). The detection was carried on a linear ion trap mass spectrometer under multiple reaction monitoring (MRM) mode with the source operated in positive mode of electrospray ionization (ESI+). Nine deuterium labeled β2-agonists were used as internal standards for quantitative analysis. The results showed that the linear ranges for 23 β2-agonists and 5 β-blockers were 0.005－0.16 mg/L, and the limits of detection were all around 0.2 μg/L. The mixed standard solution was added into the blank urine samples, and the recoveries of 23 β2-agonists and 5 β-blockers were ranged from 57.1% to 127.7% with the relative standard deviations of 1.1%-31.1%. The results demonstrate that the method is easy, fast, sensitive, and suitable for the confirmation and quantification of 23 β2-agonists and 5 β-blockers in urine samples.

Key words: urine , β2-agonists, β-blockers, high performance liquid chromatography-mass spectrometry (HPLC-MS)