Determination of Four Pesticide Residues in Pepper Oleoresin and Pepper Essential Oil Using GPC-QuEChERS-GC-MS/MS and Dietary Risk Assessment

Pepper (Piper nigrum L.), a vital spice, is abundant in flavor compounds such as piperine, sesquiterpenes, and terpenes. Pepper oleoresin and pepper essential oil are concentrated extracts of these flavor compounds, can offer enhanced culinary value. Both oleoresin and essential oils contain numerous organic compounds, including volatile oils, organic acids, alkaloids, and pigments, posing challenges in detecting pesticide residues in these products. This study introduced a method of gel permeation chromatography combined with QuEChERS gas chromatography tandem mass spectrometry (GPC-QuEChERS-GC-MS/MS) to detect pesticide residues in pepper oleoresin and essential oil, incorporating dietary risk assessment. The extraction of the pesticde was conducted using an ethyl acetate-cyclohexane (1:1, V/V) solvent system, followed by gel permeation chromatography and purification with graphitized carbon black (GCB) and N-propyl ethylenediamine (PSA) adsorbents. The multi-reaction monitoring (MRM) mode and matrix-matched calibration curves with internal standards were used for quantitative analysis. Under optimized conditions, the four pesticides have good linearity in the concentration of 3-100 μg/L with the correlation coefficients exceeding 0.99. Recoveries at three spiked levels (0.1, 0.5, 1.0 mg/kg) range from 73% to 120%, suggesting high accuracy, and the relative standard deviations (RSDs) are below 20%, demonstrating good precision. The limits of detection are 0.04-0.10 mg/kg. A survey of 20 batches of black pepper, pepper essential oil, and pepper oleoresin on the market reveals maximum residue levels of metalaxyl, chlorpyrifos, permethrin, and cypermethrin at 1.236, 0.954, 2.087, and 1.174 mg/kg, respectively. A dietary risk assessment was conducted based on the median residue values determined in the samples. The results showed that the chronic dietary intake risks for four pesticides are significantly lower than 100%, indicating minimal dietary risks. This study not only provides a reliable and sensitive method for detecting pesticide residues in pepper extracts, but also contributes to establish food safety standards for plant-based extracts. Furthermore, it can offer valuable insights for internal quality control in the food processing industry and help regulatory bodies in enforcing food safety regulation.