## 4 Materials and Methods
### Sample Treatment  
For the extraction of _Alternaria_ toxins, a 2.5 g homogenized sample was spiked with the mixture standards at concentrations of 1 \(\mathrm{\SIUnitSymbolMicro g}\) 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 MgSO\({}_{4}\) and 1 g of NaCl were immediately added and then shaken in the tube to prevent agglomeration of the salts. After centrifugation at 5000\(\times\)\(g\) for 5 min, the supernatant layer was evaporated to near dryness (about 1 mL residue left) under a nitrogen stream at 40 \({}^{\circ}\)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 \(\mathrm{\SIUnitSymbolMicro m}\) 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\(\times\)\(g\) anhydrous MgSO\({}_{4}\) 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 \(\mathrm{\SIUnitSymbolMicro m}\) nylon filter and injected into the UPLC-MS/MS system.  
The following are available online at [[http://www.mdpi.com/2072-6651/10/10/382/s1](http://www.mdpi.com/2072-6651/10/10/382/s1)]([http://www.mdpi.com/2072-6651/10/10/382/s1](http://www.mdpi.com/2072-6651/10/10/382/s1)), Figure S1: Optimization of chromatographic column for the four analytes. (a) Waters Acquity Ultra-Performance Liquid Chromatography (UPLC) Ethylene Bridged Hybrid (BEH) C18 column (1.8 \(\mathrm{\SIUnitSymbolMicro m}\), 2.1 \(\times\) 100 mm); (b) Waters Acquity UPLC High Strength Silica (HSS) T3 column (1.8 \(\mathrm{\SIUnitSymbolMicro m}\), 2.1 \(\times\) 100 mm), Figure S2: Effect of the type of clean-up agent on the extraction recoveries (ERs%) of four _Alternaria_ toxins: tenuazonic acid (TeA), alternariol (AOH), alternariol monomethyl ether (AME), and tentoxin (TEN), Figure S3: The UPLC- tandem mass spectrometry (MS/MS) chromatograms of the blank (a) and spiked (b) (80 \(\mathrm{\SIUnitSymbolMicro kg}^{-1}\)) juibube sample (S-7).  
Methodology, C.W., Y.F., W.H. and D.H.; Writing--Original Draft, C.W. and Y.F.; Writing--review & editing, A.W. and W.W.  
This research was funded by Xinjiang Academy of Agricultural Sciences (XJNKYPT-2017-003), Science and Technology Department of Xinjiang Uygur Autonomous Region (2016D04016, KY2017064), Urumqi Science and Technology Program (P161210005) The APC was funded by Xinjiang Academy of Agricultural Sciences (XJNKYPT-2017-003).  
The authors highly appreciate the financial supports from Xinjiang Academy of Agricultural Sciences (XJNKYPT-2017-003) and Science and Technology Department of Xinjiang Uygur Autonomous Region (2016D04016, KY2017064). And we also thank [PERSON] from Tarim University, who provided the juibube samples.  
The authors declare no conflict of interest.