Determination of 15 Mycotoxins in Zanba by Ultra-High Performance Liquid Chromatography Tandem Mass Spectrometry with QuEChERS

Homogenized zanba powders (1.000 g) was taken, and 5 mL of water and 10 mL of acetonitrile solution containing 10% (volume fraction) formic acid were added. After extracting for 10 min by vortex, 4 g of sodium sulfate and 1 g of sodium chloride were added. The mixture was vortexed and centrifuged, and 1.5 mL of supernatant was placed in a 2 mL-purification tube filled with 150 mg of magnesium sulfate, 100 mg of C₁₈, 100 mg of N-propyl ethylenediamine (PSA). After vortex and centrifugation, 0.8 mL of supernatant was blown to near dryness by nitrogen, and then the residue was redissolved with 0.4 mL of 20% (volume fraction) acetonitrile solution. The solution was vortexed for 5 min, and filtered by 0.22 μm filter membrane. 15 mycotoxins in the filtrate were determined by ultra-high performance liquid chromatography tandem mass spectrometry, using ACQUITY UPLC HSS T3 column as stationary phase and mixtures of 0.2% (volume fraction) formic acid solution and acetonitrile at different volume ratios as mobile phase for gradient elution. Electrospray ion (ESI) source was used for mass spectrometry. The target compounds were analyzed by multiple reaction monitoring (MRM) mode in positive and negative scanning mode. Matrix calibration standard curves were used for accurate quantification. As shown by the results, linear relationships between values of peak area and mass concentration of 15 mycotoxins were found in definite ranges, with detection limits (3S/N) in the range of 0.1-5.8 μg·kg^-1. Test for recovery was made by standard addition method, giving results in the range of 75.8%-105%, with RSDs (n=6) of the determined values less than 10%. This method was applied to the analysis of 10 batches of actual zanba samples, and it was shown that ochratoxin A (OTA) content in 2 batches of zanba samples exceeded the standard.