For the extraction of Alternaria toxins, a 2.5 g homogenized sample was spiked with the mixture standards at concentrations of 1 μg mL−1, vortexed for 20 s, and then placed in the dark for 10 min. Next, 10 mL water and 10 mL acetonitrile containing 1% acetic acid were added successively, and then shaken with an automatic horizontal shaker at 2500 rpm for 5 min to fully disperse the sample. Subsequently, 4 g of anhydrous MgSO4 and 1 g of NaCl were immediately added and then shaken in the tube to prevent agglomeration of the salts. After centrifugation at 5000× g for 5 min, the supernatant layer was evaporated to near dryness (about 1 mL residue left) under a nitrogen stream at 40 °C. Finally, 1 mL of the combined solution (acetonitrile/methanol/formic acid, 70:29:1, v/v) was added into the residue, vortexed, filtered through a 0.22 μm nylon filter and injected into the UPLC–MS/MS system.
Additionally, a clean-up step was conducted in the optimization procedure. After the above centrifugation step, the supernatant layer (about 8 mL) was transferred into a 15 mL-centrifuge tube containing 1.2× g anhydrous MgSO4 and 0.4 g PSA (or C18, Florisil and GCB). After shaking (3 min) and centrifugation (5 min at 5000 rpm), 1 mL of the supernatant was taken, filtered through a 0.22 μm nylon filter and injected into the UPLC–MS/MS system.
Additionally, a clean-up step was conducted in the optimization procedure. After the above centrifugation step, the supernatant layer (about 8 mL) was transferred into a 15 mL-centrifuge tube containing 1.2× g anhydrous MgSO4 and 0.4 g PSA (or C18, Florisil and GCB). After shaking (3 min) and centrifugation (5 min at 5000 rpm), 1 mL of the supernatant was taken, filtered through a 0.22 μm nylon filter and injected into the UPLC–MS/MS system.
Free full text: Click here
