Sensitive determination of Alternaria toxins in cereals and cereal-based foods using online MAX SPE column cleanup coupled with liquid chromatography-tandem mass spectrometry.

A sensitive technique for quantitative analysis of four Alternaria toxins (tenuazonic acid (TeA), alternariol (AOH), tentoxin (TEN), and alternariol monomethyl ether (AME)) in cereals and cereal-based foods was developed, which combined liquid chromatography-tandem mass spectrometry (LC-MS/MS) with online mixed-mode strong anion exchange (MAX) solid-phase extraction (SPE) cleanup. Online SPE cleanup came after sample preparation, which included extraction using 50 mM NaHPO aqueous-MeOH-ACN (45:10:45, v/v) and high-speed centrifugation. For quantification, isotope-labeled internal standard calibration curves were created with linear regression coefficients greater than 0.9988. The matrix effect values of Alternaria toxins ranged from -18.2 % to +22.5 %. The limits of detection (LODs) of TeA, AOH, TEN, and AME for this approach were determined to be 0.3, 0.15, 0.06, and 0.02 μg/kg, respectively. The sensitivity of this method met the EU indicative levels for infant foods. The recoveries of Alternaria toxins in rice, wheat, and corn were ranged from 86.9 % to 112.0 %, 84.2 % to 102.8 %, and 85.8 % to 105.6 %, respectively. The inter- and intra-day RSDs were lower than 10.2 %. This analytical approach was successfully applied to determine Alternaria toxins in 24 cereal-based samples from Zhoushan, China.