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

Abstract

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 using matrix-matched calibration and isotope-labeled internal standards. At the lowest spiking level, recoveries ranged from 82% (AFB1) to 111% (FB3). Repeatability and intermediate precision (RSD) were below 20% for all analytes across the 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 B2 (FB2, 4.4%), aflatoxin B1 (AFB1, 3.3%), and ochratoxin A (OTA, 3.3%). A chronic dietary risk assessment for FB2 and total zearalenone (tZEN = ZEN + α-zearalenol) indicated no health concern for tea consumers, with estimated intakes not exceeding 5% of the established PMTDI/TDI.