Abstract: An analytical method was established for the simultaneous determination of 169 pesticide residues in pepper powder by high performance liquid chromatography coupled with quadrupole-time of flight mass spectrometry (HPLC-Q-TOF MS). The samples were soaked in 0.1% (V/V) aqueous acetic acid solution, then extracted with acetonitrile and purified with C18 and Florisil sorbents. The compounds were separated on a C18 column (100 mm × 2.1 mm, 2.6 μm) using gradient elution with a mobile phase composed of 5 mmol/L ammonium formate aqueous solution and methanol, detected in the positive ion mode and quantitated by the matrix matched external standard method. Meanwhile, an accurate mass database and a fragment ion library were created for rapid qualitative and quantitative analysis of the 169 pesticides in pepper samples. The results showed that the method had a good linearity (R2 > 0.95) within the concentration range of 5–100 ng/mL for 136 pesticide compounds. The remaining 33 compounds could only be qualitatively analyzed. The recoveries for the target compounds at three spiked levels ranged from 26% to 140%, with relative standard deviations of 1.5%–36.0%. The method is simple, less time consuming and suitable for rapid and high-throughput screening of pesticide residues in pepper powder samples.

Key words: high performance liquid chromatography coupled with quadrupole-time of flight mass spectrometry; screening; pesticide residues; pepper powder