Abstract:

Objective To establish a rapid and accurate method for simultaneous determination of 16 mycotoxins，including deoxynivalenol（DON），3-acetyldeoxynivalenol（3-Ac-DON），15-acetyldeoxynivalenol（15-Ac-DON），zearalenone（ZEN），aflatoxin B₁（AFTB₁），aflatoxin B₂（AFTB₂），aflatoxin G₁（AFTG₁），aflatoxin G₂（AFTG₂）， fumonisin B₁（FB₁），fumonisin B₂（FB₂），fumonisin B₃（FB₃），ochratoxin（OTA），sterigmatocystin（ST），nivalenol（NIV），T-2 mycotoxin and HT-2 Toxin，in wheat by isotope internal standard dilution-high performance liquid chromatography tandem mass spectrometry（UPLC-MS/MS）. Methods After sample preparation，the extract was first prepared by adding a mixture of acetonitrile-formic acid-water（70+1+29，v/v%） and then subjected to initial centrifugation，dilution，and secondary centrifugation. The supernatant was filtered through a 0.22 μm filter and then added with a ¹³C-labeled isotopic internal standard. The sample was analyzed using a Venusil MP C₁₈ column（3.0 m×50 mm，3 μm），a mobile phase of 0.1% formic acid water solution and 0.1% formic acid methanol solution（ESI⁺），pure water and acetonitrile（ESI^-），and gradient elution. The sample was ionized by electrospray ionization（ESI） and the dynamic multi-reaction monitoring （DMRM） mode was used for the determination of the content of various fungal toxins. Results The correlation coefficients（r） of the 16 fungal toxins within the standard system concentration range were all ≥0.999 2，meeting the standard of "999". It can be considered that the linear performance of these 16 mycotoxins is good. The limit of detection（LOD） was 0.1-50 μg/kg，and the limit of quantification（LOQ） was 0.3-50 μg/kg. The recovery rates of six parallel measurements of 16 mycotoxins ranged from 73.13% to 122.20% at low，medium and high concentrations，and the RSD was 0.87%-9.04%. A total of 201 wheat samples from the planting process in Hebei Province were tested by this method. The results showed that：DON was detected in almost all of the 201 samples，the detection rate was 94.53%，the over-standard rate was 8.46%，and a small amount of AFTB₂（17.41%），3-Ac-DON（7.46%），ZEN，OTA，FB₁，FB₂，FB₃ and ST were detected in some samples. Conclusion The method has high sensitivity，accuracy and precision，meeting the requirements of methodology，it can be used for quality and safety risk assessment，screening，and validation analysis of fungal toxins in large-scale wheat products，which can provide reference for the detection of various mycotoxins in food safety risk monitoring，and provide technical support for the supervision of food quality and safety by relevant departments.

Key words: Mycotoxins, Ultra performance liquid chromatography/tandem mass spectrometry, Isotope internal standard dilution, Wheat