Magnetic graphitized carbon black based on crystal growth method combined with high-resolution mass spectrometry for screening of 300 pesticide residues in Radix Codonopsis and Angelica sinensis.

In this study, a high-throughput method for analyzing 300 pesticide residues in Radix Codonopsis and Angelica sinensis was established by liquid chromatography-quadrupole time-of-flight mass spectrometry (LC-Q-TOF/MS) using iron tetroxide loaded graphitized carbon black magnetic nanomaterial (GCB/Fe3O4) as the purification material. It was optimized that saturated salt water and 1 % acetate acetonitrile were used as the extraction solution, then the supernatant was purified with 2 g anhydrous CaCl2 and 300 mg GCB/Fe3O4. As a result, 300 pesticides in Radix Codonopsis and 260 in Angelica sinensis achieved satisfactory results. The limits of quantification of 91 % and 84 % of the pesticides in Radix Codonopsis and Angelica sinensis reached 10 µg/kg, respectively. The matrix-matched standard curves ranging from 10 to 200 µg/kg were established with correlation coefficients (R) above 0.99. The pesticides meeting SANTE/12682/2021 accounted for 91.3 %, 98.3 %, 100.0 % and 83.8 %, 97.3, 100.0 % of the total pesticides added in Radix Codonopsis and Angelica sinensis respectively, which were spiked at 10, 20,100 µg/kg. The technique was applied to screen 20 batches of Radix Codonopsis and Angelica sinensis. Five pesticides were detected, three of which were prohibited according to the Chinese Pharmacopoeia (2020 Edition). The experimental results showed that GCB/Fe3O4 coupled with anhydrous CaCl2 exhibited good adsorption performance and could be used for sample pretreatment of various pesticide residues in Radix Codonopsis and Angelica sinensis. Compared with the reported methods for determining pesticides in traditional Chinese medicine (TCM), the proposed method has the advantage of less time-consuming in the clean-up procedure. Furthermore, as a case study on root TCM, this approach may serve as a reference for other TCM.

Residual levels and dietary exposure risk assessment of banned pesticides in fruits and vegetables from Chinese market based on long-term nontargeted screening by HPLC-Q-TOF/MS.

The negative impact of banned pesticides is of special importance for their high toxicity. In this study, nationwide screening of banned pesticides in 37462 fruit and vegetable samples was carried out from 2012 to 2018 using a self-developed HPLC-Q-TOF/MS technique. The dietary exposure risks associated with the banned pesticides were assessed. The results showed that 66.62 % of the samples were detected at least one pesticide. Among the pesticide-positive samples, a total of 18 banned pesticides were detected in 1798 samples for 1896 times. The risk assessment revealed that 11.71 % of the positive detections exceeded the safety limits and posed an unacceptable risk, while 37.29 % of the positive detections posed acceptable risks. According to the screening and assessment results, two national maps were presented to show the total detection ratios of the banned pesticides and the unacceptable risks of dietary exposure. It should be noted that omethoate had higher residual concentration, unacceptable risk frequency and unacceptable risk proportion. This is the first nationwide comprehensive report on screening and risk assessment banned pesticides.

Automated QuEChERS for the determination of 482 pesticide residues in Radix codonopsis by GC-Q-TOF/MS and LC-Q-TOF/MS.

A rapid procedure for the determination of 482 pesticide residues in Chinese Materia Medica by GC-Q-TOF/MS and LC-Q-TOF/MS (379 pesticides for LC, 327 pesticides for GC, and 226 pesticides for both) was developed. Radix codonopsis was chosen as the matrix for verification, and a comparative study on the QuEChERS sample preparation was carried out, between a fully automated workstation and manual operation, in terms of limits of quantitation, recovery rate and RSD at 3 spiked levels of 10 µg kg-1, 20 µg kg-1 and 100 µg kg-1. In the linear range of each pesticide in a concentration range of 5-100 µg L-1, the linear correlation coefficients R2 of 85% of the pesticides for GC and 88% for LC were equal to or greater than 0.990. Taking recovery 70-120% and RSD ≤ 20% as the satisfactory standard, the automated workstation performed better at 10 µg kg-1 and 20 µg kg-1 than manual operation, and the numbers of satisfactory pesticides of GC & LC were 401 and 418 for the automated approach, and 378 and 400 for manual, while the two approaches were almost even at 100 µg kg-1, 421 vs. 424. Besides, the automated workstation presented lower RSD (more pesticides ≤10%) and better recovery quality (more pesticides within 90-110%). Following the method verification, 50 Radix codonopsis samples purchased from local markets were prepared with the automated workstation and analyzed by GC and LC-Q-TOF/MS. 18 pesticides were detected in 38 samples, one of which was a highly toxic pesticide. The automated QuEChERS workstation can handle 40 samples in one cycle within 6 hours, and realize whole-process automation covering from samples after "weighing" to "injection into vials". The batch-to-batch, day-to-day, and lab-to-lab consistency and 24 × 7 workability of the automated solution have demonstrated a promising and ideal replacement for manual operation in sample preparation.

Simultaneous determination and risk assessment of highly toxic pesticides in the market-sold vegetables and fruits in China: A 4-year investigational study.

This study investigated the levels of highly toxic pesticides (HTPs) in 6554 vegetable and fruit samples from 31 regions of China, along with the associated risk of dietary exposure for the population between 2014 and 2017. 18 HTPs were detected in 325 (4.96%) samples, and the levels of HTPs in 103 (1.57%) samples were found to be higher than the maximum residue limits (MRLs) of China. The rate of detection of HTPs in six types of vegetables and fruits, in a decreasing order, was found to be as follows: eggplant (8.84%) >grape (5.58%) >tomato (5.43%) >cucumber (5.43%) >pear (3.12%) >apple (2.30%). The level of contamination of HTPs was found to be higher in vegetables compared with fruits. The vegetable and fruit samples with the highest percentages of HTPs exceeding MRLs were found in eggplants from Guangxi (20%) and grapes from Inner Mongolia (12.5%), respectively. Both, the average target hazard quotient (THQ) of a single highly toxic pesticide (HTP) and the average hazard index (HI) of the mixture of HTPs for adults and children from vegetables and fruits from the 31 regions were found to be less than one. Omethoate, carbofuran, ethoprophos, triazophos, and phorate were identified as the major contributors to the average HI for vegetables, and carbofuran, ethoprophos, omethoate, phorate, and phosphamidon were identified as the primary contributors to the average HI for fruits. The results of this study revealed that HTPs in vegetables and fruits did not cause any significant chronic risk of dietary exposure. The detection of HTPs exceeding MRLs in some of the samples implied that appropriate management guidelines for HTPs should be implemented to protect the health of the consumers.