Determination of Urinary Mycotoxin Biomarkers Using a Sensitive Online Solid Phase Extraction-UHPLC-MS/MS Method

In the course of assessing the human exposure to mycotoxins, biomarker-based approaches have proven to be important tools. Low concentration levels, complex matrix compositions, structurally diverse analytes, and the large size of sample cohorts are the main challenges of analytical procedures. For that reason, an online solid phase extraction-ultra high-performance liquid chromatography-tandem mass spectrometry (online SPE-UHPLC-MS/MS) method was developed, allowing for the sensitive, robust, and rapid analysis of 11 relevant mycotoxins and mycotoxin metabolites in human urine. The included spectrum of analytes comprises aflatoxin M₁ (AFM₁), altenuene (ALT), alternariol monomethyl ether (AME), alternariol (AOH), citrinin (CIT) and its metabolite dihydrocitrinone (DH-CIT), fumonisin B₁ (FB₁), ochratoxin A (OTA), and zearalenone (ZEN) as well as α- and β-zearalenol (α- and β-ZEL). Reliable quantitation was achieved by means of stable isotope dilution, except for ALT, AME and AOH using matrix calibrations. The evaluation of method performance displayed low limits of detection in the range of pg/mL urine, satisfactory apparent recovery rates as well as high accuracy and precision during intra- and interday repeatability. Within the analysis of Zimbabwean urine samples (n = 50), the applicability of the newly developed method was shown. In addition to FB₁ being quantifiable in all analyzed samples, six other mycotoxin biomarkers were detected. Compared to the occurrence rates obtained after analyzing the same sample set using an established dilute and shoot (DaS) approach, a considerably higher number of positive samples was observed when applying the online SPE method. Owing to the increased sensitivity, less need of sample handling, and low time effort, the herein presented online SPE approach provides a valuable contribution to human biomonitoring of mycotoxin exposure.

Online specific recognition of mycotoxins using aptamer-grafted ionic affinity monolith with mixed-mode mechanism

Herein, a facile and practical aptamer-grafted ionic affinity monolith with mixed-mode mechanism was explored as a versatile platform for online specific recognition of polar and non-polar mycotoxins. The mixed-mode mechanism including molecular affinity adsorption (between aptamers and targets), hydrophilic interaction and ionic interaction (between stationary phase and targets) were adopted and provided a better flexibility in adjusting separation selectivity to reduce nonspecific adsorption with respect to the single mode. Preparation and characterization of aptamer-based affinity monoliths were investigated, The characterization of pore size distribution, Brunauer-Emmett-Teller (BET) surface area and the specificity and cross-reaction were also evaluated. As a result, the hydrophilic nature and negative charge on affinity monolith were obtained. Multiple interactions including aptamer affinity binding, hydrophilic interaction (HI) and ion exchange (IE) could be adopted for online selective extraction. Specific recognitions of polar ochratoxin A (OTA), non-polar zearalenone (ZEN) and aflatoxin B1 (AFB1) was fulfilled with LODs as 0.03, 0.05 and 0.05 μg/L, respectively. Applied to real cereals, good recoveries of the fortified OTA, AFB1 and ZEN were achieved as 92.6 ± 1.3% ~ 95.6 ± 1.3% (n=3), 93.9 ± 2.3% ~ 98.2 ± 3.4% (n=3) and 92.7 ± 2.0% ~ 96.9 ± 3.5% (n=3) in corn, wheat and rice, respectively. The results displayed that Apt-MCs with hydrophilic and ionic interaction mixed-mode mechanism were efficient enough and competent for the online recognition of mycotoxins in cereals.

QuEChERS-LC-QTOFMS for the simultaneous determination of legislated and emerging mycotoxins in malted barley and beer using matrix-matched calibration as a solution to the commercial unavailability of internal standards for some mycotoxins

The combination of QuEChERS-LC-QTOFMS and matrix-matched calibration (MMC) to simultaneously determinate legislated and emerging mycotoxins in malt and beer was evaluated for the first time. The method performance was satisfactory displaying suitable linearity (R² >0.99) and recovery (71-102%). The lowest values (in μg kg^-1) of LOD (0.01) and LOQ (0.05) were found for enniatins, while the highest LOD (15) and LOQ (50) were reported for fumonisin B1. Precision and sensitivity (RSD <10%) were in accordance with the different guidelines of method validation. MMC was important to avoid inaccurate quantification of all mycotoxins due to signal enhancement or suppression. Another advantage was the enhanced throughput, requiring 1.2 min of analysis per analyte. The detection of legislated (aflatoxins, ochratoxin A, deoxynivalenol, fumonisin B1, zearalanone, T-2 and HT-2 toxin) and emerging mycotoxins (enniatins, beauvericin, moniliformin and sterigmatocystin) allowed verifying compliance with legislation and generating data to support the establishment of limits for emerging mycotoxins.

Development and validation of an analytical method for the extraction, identification, and quantification of multi-mycotoxins in beer using a modified QuEChERS procedure and UHPLC-MS/MS

Although beer is one of the most popular alcoholic beverages in the world, there is no specific legislation regarding contaminants, especially mycotoxins, for this product. The present manuscript reports the development and validation of an analytical methodology based on the QuEChERS approach, followed by quantification via UHPLC-MS/MS for the simultaneous determination of seventeen mycotoxins in beer. During the validation, amatrix effect was observed for 82% of the analytes. Linearity and recovery were evaluated using spiked blank samples, and the chosen methodology proved to be efficient for all analytes, with recoveries ranging from 71 to 118%, excepting ergonovine, for which recovery of 57% was achieved. Precision was estimated in terms of repeatability and reproducibility, with variations from 2.6 to 28.2% and 9.7 to 28.7%, respectively. The detection (LOD) and quantification (LOQ) limits, determined from the values of CCα and CCβ, ranged from 0.26 to 117 µgkg^-1 and from 0.30 to 135 µgkg^-1, respectively. Measurement uncertainties were based on the bottom-up methodology, with uncertainties ranging from 0.03 to 17 µgkg^-1. Finally, thirty-eight beer samples, collected at the local market, were analysed, and 16 of them showed contamination by deoxynivalenol in concentrations ranging from 159 ± 26 µgkg^-1 to 648 ± 106 µgkg^-1.