2.3. UHPLC-MS/MS Parameters

UHPLC-MS/MS analysis of flonicamid was performed using a Waters ACQUITY UHPLC^®BEH C₁₈ column (2.1 mm × 50 mm; i.d., 1.7 μm) equipped with an electrospray ionization (ESI) source. The flow rate was 0.2 mL/min, and the injection volume was 1 μL. Formic acid (0.05%) in deionized water and methanol were used for gradient elution. The gradient elution parameters are listed in Table S2. Reliable and fast separation of flonicamid was achieved under the optimized UHPLC conditions. Multiple reaction monitoring (MRM) was utilized to quantify and selectively detect the pesticide in a variety of crops. MS/MS was carried out using an electrospray ionization source in negative ion mode.