[QuEChERS-liquid chromatography-tandem mass spectrometry for determination of 22 triazole pesticide residues in Chinese herbal medicines].

Eight well-known herbals in Zhejiang Province, Zhebawei, are commonly used as traditional Chinese herbal medicines owing to their rich active ingredients. However, the unavoidable use of pesticides during agricultural production has led to pesticide residue problems in these herbs. In this study, a simple, rapid, and accurate method was established to determine 22 triazole pesticide residues in Zhebawei. An improved QuEChERS method was used for sample pretreatment, and Rhizoma Atractylodis Macrocephalae was used as a representative sample. The sample was extracted with acetonitrile to eliminate some polar and nonpolar compounds, pigments, and other impurities, and the purification effects of multiwalled carbon nanotubes (MWCNTs), amino-modified multiwalled carbon nanotubes (MWCNTs-NH2), carboxylated multiwalled carbon nanotubes (MWCNTs-COOH), crosslinked polyvinylpyrrolidone (PVPP), zirconium dioxide (ZrO2), 3-(N,N-diethylamino)-propyltrimethoxysilane (PSA), octadecyl (C18), and graphitized carbon black (GCB) were compared. MWCNTs-COOH and C18 were selected as the purification adsorbents, and their dosages were systematically optimized. The combination of 10 mg of MWCNTs-COOH and 20 mg of C18 was eventually selected as the purification adsorbents. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) was used for analysis, and box graphs were plotted to present the dispersion of each group of recoveries, thus enabling the identification of the data outliers, dispersion distribution, and data symmetry. The established method was systematically verified and showed good linearity over the concentration range of 1-200 µg/L (except for bromuconazole, epoxiconazole, and etaconazole) with correlation coefficients >0.99. The average recoveries of the 22 pesticides at spiked levels of 10, 20, 100, and 200 µg/kg were in the range of 77.0%-115% with relative standard deviations (RSDs) <9.4%. The limits of detection and quantification were 1-2.5 µg/kg and 10-20 µg/kg, respectively. The applicability of the developed method to other herbals was investigated at 100 µg/kg, and the average recoveries of the target pesticides in different matrices ranged from 76.4% to 123% with RSDs <12.2%. Finally, the method established was used to detect triazole pesticide residues in 30 actual Zhebawei samples. The results showed that triazole pesticides were present in Bulbus Fritillariae Thunbergii and Dendranthema Morifolium. Difenoconazole was detected in Bulbus Fritillariae Thunbergii at contents ranging from 41.4 µg/kg to 110 µg/kg, while difenoconazole, myclobutanil, triadimenol and propiconazole were detected in Dendranthema Morifolium at contents ranging from 16.1 µg/kg to 250 µg/kg. The established method can meet the requirements for the accurate quantitative analysis of triazole fungicides in Zhebawei.

Phenolic-based non-ionic deep eutectic solvent for rapid determination of water soluble neonicotinoid insecticides in tea infusion.

Challenges were raised to established analytical method for monitoring water soluble neonicotinoid insecticide (NEOs) residues in tea infusion. Phenolic-based non-ionic deep eutectic solvent (NIDES) composed by a mixture of DL-menthol and thymol (molar ratio of 1:3) was applied to achieve the determination of selected NEOs. Factors influenced extraction efficiency have been evaluated and molecular dynamics approach was conducted aming to provide a new insight to explain its extraction mechanism. It is found that Boltzmann averaged solvation energy of NEOs was negatively correlated with extraction efficiency. The method validation results indicated good linearities (R2 ≥ 0.99), sensitive LOQs (0.05 µg L-1), high precisions (RSD < 11%) and satisfactory recoveries (57.7%∼98%) at 0.05 µg L-1 âˆ¼ 100 µg L-1. The intake risk of NEOs in tea infusion samples were acceptable which residues in range of 0.1 µg L-1 âˆ¼ 3.5 µg L-1 for thiamethoxam imidacloprid and thiacloprid. This method showed advantages of rapid, green, and easy operation.

Removal of Matrix Interferences by Nano-MgO and Co-Adsorbents for Accurate Multi-Pesticide Residue Analysis in the Chinese Medicinal Herb, Paeoniae Radix Alba.

A simple, accurate, and high-throughput analytical method was developed to detect 123 pesticide residues in Chinese medicinal herb Paeoniae Radix Alba (PRA) by introducing nano-MgO as a highly efficient purification material based on quick, easy, cheap, effective, rugged, and safe (QuEChERS) design concept. Various PRA samples were extracted using 8 mL 0.5% acetic acid-acetonitrile solution and purified by a dispersive solid-phase extraction method with 30 mg nano-MgO, 40 mg primary secondary amine (PSA), and 40 mg octadecylsilane (C18) as the cleanup adsorbents, followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). 70.7% of pesticides showed a weak matrix effect after the purification process, indicating that this method can give the precise quantitative analysis of trace pesticides residue. The method was systematically validated under optimal conditions in five different kinds of PRA samples; good linearity was observed in the concentration range of 0.5-250 µg/L or 1-250 µg/L. Pesticide recovery in each sample spiked at concentrations of 20, 50, and 200 µg/kg ranged from 98.0% to 111% and the mean relative standard deviation ranged from 2.72% to 5.70%. Furthermore, the method comparison with the traditional QuEChERS method suggested the feasibility, advantages, and potential application prospect of the present method for the multi-pesticide residue analysis in various PRA samples.

Simultaneous determination of 114 pesticides in complex Chinese herbal medicine Fritillaria using ordered mesoporous carbon CMK-3 as a reversed-dispersive solid phase extraction sorbent.

Fritillaria, a traditional Chinese herbal medicine, is classified into many medicinal species and contains numerous complex components. It is thus difficult to simultaneously detect multiple pesticide residues in different Fritillaria species. An easy, reliable, and widely applicable analytical method based on a modified Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) method coupled with LC-MS/MS was developed to solve these problems encountered during pesticide residue analysis in complex Fritillaria matrices. Ordered mesoporous carbon CMK-3 and a primary secondary amine (PSA) were used as efficient purification sorbents by optimization of the QuEChERS process. Systematic method validation was performed for four species of Fritillaria. The matrix effect of pesticides varied among different Fritillaria species, and matrix-matched standard solutions were thus employed for quantitative analysis. The mean recoveries of all pesticides ranged from 88.6% to 95.5%, with mean relative standard deviations (RSD) lower than 6% at spiked concentrations of 30, 120, and 240 µg kg-1. The limits of quantification (LOQ) for the developed method were in the range of 30-120 µg kg-1. This method was further used to analyze 47 Fritillaria samples from Zhejiang province, China, and seven pesticides were detected in 22 Fritillaria samples. These results demonstrate that the developed method is suitable for an accurate analysis of multiple pesticide residues in various Fritillaria.