Untargeted screening, method validation, and dietary risk assessment of pesticide residue in coix seed using HPLC-MS/MS
Description
Figure Captions Figure S1. Matching information of six quality control compounds in the coix seed matrix. Figure S2. Mature seeds of four coix seed varieties: (a) CS1, (b) CS2, (c) CS3, (d) CS4. Figure S3. Distribution of the pesticide multi residues in all the samples. Figure Captions Table S1. CAS number, Molecular weight, and classification of 39 compounds. Table S2. Information on coix seed varieties. Table S3. Nontarget screening gradient elution procedure. Table S4. LC-MS/MS parameters of selected pesticides in coix seed. Table S5. Regression equations, correlation coefficients (R2), matrix effect (ME), mean recovery (%) for 39 pesticides in CS2. Table S6. Regression equations, correlation coefficients (R2), matrix effect (ME), mean recovery (%) for 39 pesticides in CS3. Table S7. Regression equations, correlation coefficients (R2), matrix effect (ME), mean recovery (%) for 39 pesticides in CS4. Table S8. Mean recovery (%), intraday (RSDR), and interday (RSDr) precision validation in CS2. Table S9. Mean recovery (%), intraday (RSDR), and interday (RSDr) precision validation in CS3. Table S10. Mean recovery (%), intraday (RSDR), and interday (RSDr) precision validation in CS4. Table S11. Detection rates and maximum residue limits of pesticides in 126 coix seed samples.
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Chemicals and reagents Standard materials with purity ranging from 95.0 to 99.9% were obtained from Beijing Tan Mo Quality Control Technology Co., LTD (Beijing, China) (Table S1). Acetonitrile, methanol, and formic acid were chromatographically pure purchased from Macklin Biochemical Co., Ltd (Shanghai, China). Analytical-grade NaCl and anhydrous MgSO4 were purchased from Chuandong Chemical (Group) Co., LTD. (Chongqing, China). Secondary amine (PSA), octadecylsilane (C18), and graphitized carbon black (GCB) were purchased from Bonaigel Technology Co., LTD. (Tianjin, China). Distilled water purchased from A.S. Watson TM Limited. (UK). Mixed standard solutions The standard stock solution (1000 µg·mL-1) was prepared by dissolving 10.0 ± 0.0001 mg of individual pesticides in a 10 mL volumetric flask. A working standard solution was prepared by diluting the standard stock solution to the desired concentration. Different concentrations of the mixed standard solutions were used for the linearity and recovery studies. All standard solutions were stored in a freezer cabinet at low temperatures to prevent solvent loss and water entry. A series of matrix-matched standard working solutions were prepared by spiking four coix seed blank sample matrices to reduce matrix effects and quantitatively analyze target pesticides. Sample sources Coix seed samples were collected from various cultivation sites and local markets within Guizhou Province, China (Figure 1). 126 samples of different varieties were collected, including Qian coix seed 1 (CS1), Qian coix seed 2 (CS2), Xingren White Shell (CS3), and Guizhou coix seed (CS4). Each sample weighing approximately 1 kg was collected in sterile polyethylene bags (NY/T 788-2018). The ripe seeds of these cultivars differed in size and color (Figure S2). Grinding into powder and stored at -20℃ before pesticide residue detection. Blank samples of coix seed were obtained from the Guizhou provincial agricultural science plantation, and it was confirmed that no pesticides were used. Extraction and cleanup procedure Homogenized samples (5 g) were placed in 50 mL polypropylene tubes and mixed with 10 mL distilled water (The same treatment was used for the blank sample without pesticides). Acetonitrile (10 mL) containing 2% formic acid was added, and the mixture was left to stand for 30 min. Anhydrous MgSO4 (4 g) and NaCl (3 g) were added. The sample mixture was vigorously shaken in a multi-tube vortex for 5 min and centrifuged at 8000 rpm for 5 min. After centrifuging, the supernatant layer (1.5 mL) was transferred into a 2 mL centrifuge tube containing 100 mg octadecylsilane, 100 mg secondary amine, 15 mg graphitized carbon black, and 200 mg anhydrous magnesium sulfate. The mixture was cleaned for 2 min, and the tube was centrifuged at 8000 rpm for 5 min. The purified solution was filtered using a 0.22 µm organic filtration membrane and assayed by HPLC-MS/MS.
Institutions
- Guizhou University