Mycotoxins occurrence in dry herbs used for tea preparation: method validation, analysis of bulk samples and dietary risk assessment

In this work, a multi-mycotoxin analytical method was validated for the determination of 15 mycotoxins and related metabolites in dry herbs commonly used for tea preparation. Samples were extracted using a modified QuEChERS procedure, and quantification was performed by UHPLC-MS/MS with matrix-matched calibration and isotope-labeled internal standards dilution. At the lowest spiking level, recoveries ranged from 82% (AFB ₁ ) to 111% (FB ₃ ). Repeatability and intermediate precision (RSD) were below 20% for all analytes across three fortification levels. Ninety-one samples representing 33 types of dry herbs were analyzed, of which 25.3% were positive (≥ LOQ) for at least one mycotoxin. Zearalenone (ZEN) was the most frequently detected analyte (13.2%), followed by fumonisin B ₂ (FB ₂ , 4.4%), aflatoxin B ₁ (AFB ₁ , 3.3%), and ochratoxin A (OTA, 3.3%). A chronic dietary risk assessment for FB ₂ and total zearalenone (ZEN + α-zearalenol) indicate no health concern for tea consumers, with estimated intakes not exceeding 5% of the established Health-Based Guidance Values.