Development of a method for the quantification of six mycotoxins in cereal samples using isotope-coded derivatization combined with ultra-high-performance liquid chromatography-tandem mass spectrometry

Mycotoxins are frequently found in food samples and have become a major concern in the maintenance of food safety and human health. In this study, we developed an isotope-coded derivatization (ICD) method for the quantification of six mycotoxins in various complex matrices by using ultra-high-performance liquid chroma-tography-tandem mass spectrometry (UHPLC-MS/MS). The targeted mycotoxins were ochratoxin A, ochratoxin B, fumonisin B1, fumonisin B2, zearalenone, and zearalanone. The mycotoxins in the actual samples and stan-dards were derivatized with d0-dansyl chloride and its heavy form, d4-dansyl chloride. A mixture of light-isotope-and heavy-isotope-labeled derivatives was subjected to UHPLC-MS/MS, and isotopic internal calibration quan-tification of all targeted mycotoxins was achieved. The retention time difference between light-isotope-and heavy-isotope-labeled derivatives was less than 0.02 min, and the analysis could be completed within 7.5 min. The developed method was validated in terms of its sensitivity, precision, and accuracy. The obtained limits of detection were in range of 31.03-38.15 ng/L, and the accuracy was 97.13-104.1% with a precision of less than 3.42%. This method was also successfully applied to analyze mycotoxins in three selected cereal samples (corn, wheat, and sorghum), achieving recoveries of 71.3-92.6%. The ICD strategy provides an alternative assay to isotopic internal standards, thereby helping to effectively minimize matrix effects during mass spectrometry analysis. The proposed ICD-based UHPLC-MS/MS method has high potential for the determination of amino-and phenol-containing mycotoxins in various food samples.