Abstract:

A rapid direct-analysis method using atmospheric pressure solids analysis probe coupled to tandem mass spectrometry(ASAP-MS/MS) was established for the detection of thirteen commonly used multi-class pesticides in vegetables, without cleanup, concentration or chromatographic separation, and a single run can be done in minutes. To compensate for the poor precision and instability in ambient ionization technique, ASAP source parameters of the corona discharge, desolvation gas temperature, sample solvent and sample-load mode were optimized. The target compound was identified by product ion abundance ratios in multiple reaction monitoring(MRM)mode and semi-quantified through internal standard calibration curves. The matrix effects of celery, leek and rape were analyzed, and had apparent influences. Under the optimal conditions, the linear range was 5.0—500 μg/L with a coefficient of above 0.995. The limit of quantification(LODs) of analytes were 0.04—0.89 μg/kg, with a precision of 5.1%—13.0%(n=7). The real sample determination shows that the results by ASAP-MS/MS were in accordance with those obtained by ultra performance liquid chromatography coupled to tandem mass spectrometry(UPLC-MS/MS). The proposed ASAP-MS/MS technique can be a powerful tool due to its convenience, rapid, reliable, low-cost and eco-friendly for pesticide screening and emergency monitoring.

Key words: Atmospheric pressure solids analysis probe(ASAP), Tandem mass spectrometry, Pesticide residue, Rapid determination