Concerns about the pesticide residues in medicinal herbs have markedly increased in recent years. To ensure the safety of the herbal products, it is important to regulate the uses of pesticides and to monitor their levels for compliance. The current analytical methods applied in many routine laboratories on pesticide residue control generally consist of 100-200 compounds, which may be insufficient with the perspective of over 800 pesticides present on the market.
In this study, a semiautomated qualitative method for target screening of 508 pesticide residues in Panax notoginseng was developed using ultra-high performance liquid chromatography coupled to quadrupole-Orbitrap high resolution mass spectrometry (UHPLC-Q-Orbitrap). Full MS/dd-MS2 (data dependent acquisition) was utilized for sample data acquisition, and the screening detection limits (SDLs) ≤0.05 mg/kg were achieved for 95% of the investigated pesticides. Meanwhile, a reliable quantitative method for simultaneous determination of 508 pesticide residues in Panax notoginseng was also developed and validated using ultra-high performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS). Satisfactory linearity with correlative coefficient (R2) > 0.98 was achieved for all analytes. The limits of quantitation (LOQs) were 0.01 mg/kg for all analytes. Recoveries of 412 analytes at four levels (0.01, 0.05, 0.10 and 0.20 mg/kg) were between 70% and 120% with relative standard deviation <15%.
The combination of the above two analytical systems can simplify the routine workflow for multi-residue analysis of large scale pesticides with less workload and better performance.