GC/LC-Q-TOF/MS Method for Determining Pesticides in Traditional Chinese Medicine

Scientists from the Food Laboratory of Zhongyuan in Henan, China and the Chinese Academy of Inspection and Quarantine in Beijing, China recently tested a new gas chromatography/liquid chromatography-quadrupole time-of-flight/mass spectrometry (GC/LC-Q-TOF/MS)-based method for determining pesticides in traditional Chinese medicine (TCM), publishing their findings in the Journal of Chromatography A (1).

Vaporiser des plantes dans un jardin, jardinage entretien et protection contres les pucerons et les maladies | Image Credit: © Delphotostock - stock.adobe.com

Angelica sinensis, also known as dong quai root, is a TCM that has been used for more than 1000 years as a spice, tonic, and medicine in China, Korea, and Japan (2). Sometimes referred to as “female ginseng,” dong quai has been combined with other herbs to treat women’s reproductive problems, such as painful menstruation, and to improve blood flow.

Pesticides are often used in cultivating Angelica sinensis to prevent and control brown spot and root rot; however, currently isobutyl urea and fludioxonil are registered and allowed to be used on said plant. A recent study reported 14 pesticides being detected in Angelica sinesis, including 5 banned pesticides (3). The plant is susceptible to contamination by various mycotoxins, such as aflatoxin and ochratoxin, during planting, harvesting, and storage.

In this study, the scientists developed an applicable method that could determine 33 pesticides (54 compounds), 11 mycotoxins, and functional compounds, such as ferulic acid, simultaneously. The sample pretreatment method’s compatibility for pesticides, mycotoxins, and functional components was improved by optimizing the acidity of extraction solvents, the volumetric solution, and more. Four pretreatment methods were compared with the PRiME HLB SPE pretreatment method being deemed the most optimal. This SPE product is said to provide reversed-phase cleanup of acidic, basic, and neutral compounds forming complex sample matrices, having been designed to simplify SPE with easy-to-follow protocols (4). Among 65 contaminants, 38 of which were determined by liquid chromatography (LC) and 41 via gas chromatography (GC), which showed good linearity (R2 > 0.9801), 97% of them had a limit of quantitation (LOQ) of lower than 0.02 mg kg-1. Recovery for all compounds were suited between 70–120%, with relative standard deviations (RSD) being all lower than 20% at the spiked levels of LOQ, 2 × LOQ, and 10 × LOQ. For ferulic acid, the LOQ was 50 ng/mL, with good linearity (R2=0.9988) be9jg shown within the range of 0.5–10 µg/mL. The recovery and RSD were 98.1 %, and 3.2 % (n = 6), respectively.

The team developed a method for the simultaneous determination of pesticides, mycotoxins, and ferulic acid in Angelica sinensis via high-resolution mass spectrometry (HRMS). This method met the monitoring requirements of the Chinese Pharmacopoeia with high efficiency and rapidity. By optimizing purification technology, extraction acidity, and constant volume solution, the scientists designed a comprehensive scheme that can be compatible with various detection techniques for different types of compounds, they wrote Moving forward, this method could potentially be extended to more categories and analytes of TCM samples.

References

(1) Bai, R.; Chang, Q.; Zhang, H.; et al. Simultaneous Determination of Pesticides, Mycotoxins and Ferulic Acid in Angelica sinensis by GC/LC-Q-TOF/MS. J. Chromatogr. A 2024, 1737, 465437. DOI: 10.1016/j.chroma.2024.465437

(2) Dong quai. Mount Sinai 2024. https://www.mountsinai.org/health-library/herb/dong-quai (accessed 2024-11-4)

(3) Luo, L.; Dong, L.; Huang, Q.; Ma, S.; et al. Detection and Risk Assessments of Multi-Pesticides in 1771 Cultivated Herbal Medicines by LC/MS-MS and GC/MS-MS. Chemosphere 2021, 262, 127477. DOI: 10.1016/j.chemosphere.2020.127477

(4) Oasis PRiME HLB 6 cc Vac Cartridge, 200 mg Sorbent per Cartridge, 30/pk. Waters Corporation 2024. https://www.waters.com/nextgen/us/en/shop/sample-preparation--filtration/186008057-oasis-prime-hlb-6-cc-vac-cartridge-200-mg-sorbent-per-cartridge-.html (accessed 2024-11-4)