Simultaneous Determination of Multi-mycotoxins in Cereal Grains by LC-MS/MS

Introduction: Aflatoxins (B₁, B₂, G₁, and G₂), ochratoxin A, fumonisins (B₁ and B₂), nivalenol, deoxynivalenol, 3-acetyldeoxynivalenol, zearalenone, T-2 toxin, and HT-2 toxin are major mycotoxins found in agricultural crops. Since these mycotoxins can occur simultaneously in cereal grains, it is needed to determine the levels of the multi-mycotoxins in the grains.

Purpose: The purpose of this study was to establish a highly sensitive and reliable analytical method for simultaneous determination of the 13 mycotoxins in cereal grains by liquid chromatography-mass spectrometry (LC-MS/MS) after immunoaffinity column clean-up and to monitor the levels of the mycotoxins in the samples collected from retail markets in South Korea by using the validated analytical method.

Methods: We evaluated the linearity, sensitivity, specificity, and accuracy of the analytical methods for the mycotoxins in cereal grains by LC-MS/MS after improved toxin extraction and purification using Myco6in1⁺ immunoaffinity columns. The methods were used to determine the levels of the multi-mycotoxins in a total of 257 cereal grains (brown rice, maize, millet, sorghum, and mixed cereal) collected from South Korea.

Results: The calibration curves of the mycotoxins showed higher r² than 0.999 by using LC-MS/MS. The recovery rates of the mycotoxins in rice were 73.9-133.0% along with RSD_r of 1.65 - 14.31% at 1.24 - 100 ng/g of the spiked levels. The limits of quantification of the method for the mycotoxins were in the range of 0.6 - 6.0 µg/kg. The occurrence of the mycotoxins ranged from 1.2% to 78.6%. The co-incidence of more than two mycotoxins was 65% in brown rice, 37% in maize, 85% in millet, 94% in sorghum, and 72% in mixed cereal samples, respectively.

Significance:  The established method was proven to be suitable for assessment of the levels of multi-mycotoxins in cereal grains.