Intellistart

The separation and quantitation of bisphenol A analogues were performed on a Waters Acquity Ultra Performance Liquid Chromatography (UPLC) system (Milford, MA, USA) coupled to a Waters Xevo TQD triple quadrupole mass spectrometer (Milford, MA, USA). Ten μL of sample extract was injected in full loop and the separation was performed at 30 °C on an Acquity UPLC BEH C₁₈ column (1.7 μm, 2.1 mm × 50 mm, Waters) with a Van Guard BEH C₁₈ pre-column (1.7 μm, 2.1 × 5 mm, Waters). The mobile phase consisted of (A): 5% methanol in water and (B): 2 mM NH₄OH in methanol. The gradient program was as follows: initial gradient 100% (A) hold for 1min, to 55% (B) in 1 min, to 100% (B) in 10 min, back to 100% (A) in 0.5 min, and hold for 3.5 min at 100% (A). Flow rate was set at 0.2 mL/min. The MS/MS was operated in multiple reaction monitoring (MRM) using electrospray ionization in negative ion mode (ESI-). The MRM transitions and MS parameters were obtained and optimized using Waters IntelliStart (Waters, MA, USA). MRM transitions and optimized MS parameters are summarized in Table 1. Source temperature, desolvation temperature, and gas flow were set at 150 °C, 350 °C and 600 L/h, respectively. Capillary voltage was set at 2.5 kV and extractor voltage at 10 V.