5.5. LC-TOF/MS and LC-TOF-MS/MS Analysis for Biodegradation Products

The assay was carried out according to the method of Dong et al. [12] with slight modifications. The identification and confirmation of the major degradation product of patulin was performed by an Agilent 1290 Series containing a degasser, quaternary pump, column oven and automatic sampler, and interfaced with an Agilent 6540 Q-TOF accurate mass spectrometer with an electrospray ionization source. Samples were analyzed in the negative ionisation mode. An Agilent Zorbax SB-C18 column (100 × 2.1 mm, 1.8 μm) was used and the mobile phase was a mixture of water and acetonitrile (90:10, v/v) with a flow rate of 0.3 mL/min. The mass spectrometer conditions were as follows: gas temperature, 325 °C; drying gas (nitrogen), 12 L/min; nebuliser pressure, 40 psi; capillary voltage, 3500 V; skimmer, 65 V; and octopole radiofrequency voltage, 750 V. The mass scan was over the range of m/z 50–1000. Data analysis was performed with Agilent Mass Hunter Workstation software. For MS/MS analysis, collision-induced dissociation (CID) of 10 eV was used to obtain a distinct fragmentation.