Simultaneous screening analysis of multiple β-blockers in urine by gas chromatography–mass spectrometry in selected ion monitoring mode

A rapid screening procedure is described for the simultaneous determination of 13 β-blockers in urine at the range of 0.010–1.0 μg mL −1. The procedure involves N-ethoxycarbonyl (EOC) derivatization of β-blockers in urine sample, followed by extraction and further conversion to trimethylsilyl (TMS) derivatives for the analysis by gas chromatography–mass spectrometry (GC–MS) in selected ion monitoring (SIM) mode (GC-SIM-MS). The characteristic fragment ions at m/ z 260 and m/ z 144, and [ M − 15] + ions permitted sensitive and selective detection of most of the β-blockers in the presence of co-extracted urinary amino alcohols at much higher levels. The whole procedure of EOC/TMS derivatization with subsequent GC-SIM-MS analysis was linear ( r ≥ 0.9988). The LODs were varied from 0.03 to 2.7 ng mL −1. The ranges of precision (%relative standard deviation) and accuracy (%relative error) of the overall procedure at two different added amounts (0.02 and 0.5 μg mL −1) in urine matrix varied from 1.3 to 9.4 and from −9.6 to 9.7, respectively. The recoveries were measured to be ranged from 90.4 to 109.7%.