Development of a Sensitive and Reliable UHPLC-MS/MS Method for the Determination of Multiple Urinary Biomarkers of Mycotoxin Exposure

Assessing human exposure to pesticides and mycotoxins: optimization and validation of a method for multianalyte determination in urine samples

Humans are exposed to an increasing number of contaminants, with diet being one of the most important exposure routes. In this framework, human biomonitoring is considered the gold standard for evaluating human exposure to chemicals. Pesticides and mycotoxins are chemicals of special concern due to their health implications. They constitute the predominant border rejection notifications for food and feed in Europe and the USA. However, current biomonitoring studies are focused on a limited number of compounds and do not evaluate mycotoxins and pesticides together. In this study, an analytical method has been developed for the determination of 30 pesticides and 23 mycotoxins of concern in urine samples. A salting-out liquid-liquid extraction (SALLE) procedure was optimized achieving recoveries between 70 and 120% for almost all the compounds and limits as lower as when QuEChERS was applied. The compounds were then determined by liquid chromatography coupled to triple quadrupole mass spectrometry. Different chromatographic conditions and analytical columns were tested, selecting a Hypersild gold aQ column as the best option. Finally, the method was applied to the analysis of 45 urine samples, in which organophosphate and pyrethroid pesticides (detection rates (DR) of 82% and 42%, respectively) and ochratoxin A and deoxynivalenol (DR of 51% and 33%, respectively) were the most detected compounds. The proposed analytical method involves the simultaneous determination of a diverse set of pesticides and mycotoxins, including their most relevant metabolites, in human urine. It serves as an essential tool for biomonitoring the presence of highly prevalent contaminants in modern society.

Evaluation of distribution of emerging mycotoxins in human tissues: applications of dispersive liquid-liquid microextraction and liquid chromatography-mass spectrometry

In this work, a complete study of the distribution of emerging mycotoxins in the human body has been carried out. Specifically, the presence of enniatins (A, A1, B, B1) and beauvericin has been monitored in brain, lung, kidney, fat, liver, and heart samples. A unique methodology based on solid-liquid extraction (SLE) followed by dispersive liquid-liquid microextraction (DLLME) was proposed for the six different matrices. Mycotoxin isolation was performed by adding ultrapure water, acetonitrile, and sodium chloride to the tissue sample for SLE, while the DLLME step was performed using chloroform as extraction solvent. Subsequently, the analysis was carried out by high-performance liquid chromatography coupled to tandem mass spectrometry (HPLC-MS/MS). The proposed method allowed limits of quantification (LOQs) to be obtained in a range of 0.001-0.150 ng g-1, depending on the tissue and mycotoxin. The precision was investigated intraday and interday, not exceeding of 9.8% of relative standard deviation. In addition, trueness studies achieved 75 to 115% at a mycotoxin concentration of 25 ng g-1 and from 82 to 118% at 5 ng g-1. The application of this methodology to 26 forensic autopsies demonstrated the bioaccumulation of emerging mycotoxins in the human body since all mycotoxins were detected in tissues. Enniatin B (ENNB) showed a high occurrence, being detected in 100% of liver (7 ± 13 ng g-1) and fat samples (0.2 ± 0.8 ng g-1). The lung had a high incidence of all emerging mycotoxins at low concentrations, while ENNB, ENNB1, and ENNA1 were not quantifiable in heart samples. Co-occurrence of mycotoxins was also investigated, and statistical tests were applied to evaluate the distribution of these mycotoxins in the human body.

Mycotoxin Determination in Peaches and Peach Products with a Modified QuEChERS Extraction Procedure Coupled with UPLC-MS/MS Analysis

Peaches are the most significant temperate fruit crop worldwide. However, peach fruits are susceptible to fungal and mycotoxin contamination. Consequently, monitoring the residual levels of multiple mycotoxins in peaches and related products is essential. In this study, a novel method based on QuEChERS extraction, followed by ultra-high-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) detection, was developed for analyzing 14 mycotoxins in peaches and peach products from China. Matrix-matched calibrations were employed to accurately quantify the mycotoxins and compensate for matrix effects. Recoveries for the target analytes ranged from 84.6% to 117.6%, with intra-day and inter-day precision below 20%. The limits of quantification were 2 or 5 μg/L for the 14 mycotoxins. This method was utilized to detect the presence of target mycotoxins in 109 fresh peaches, 100 diseased peaches, and 89 peach products from China. Six mycotoxins were identified in the rotten parts of the diseased peaches, with concentrations ranging from 5.2 to 1664.3 µg/kg. In the remaining parts of the diseased peach samples, only two toxins, alternariol (AOH) and alternariol monomethyl ether (AME), were quantified at levels of 15.3 µg/kg and 15.5 µg/kg, respectively. No mycotoxins were detected in fresh peaches. For peach products, all contamination levels were below the quantitative limits and significantly lower than the maximum legal limits established for the products.

Development of an LC-MS/MS method for the determination of multiple mycotoxins in human urine

A sensitive liquid chromatography-tandem mass spectrometry method was developed for the determination of 17 mycotoxins in human urine. The method incorporates a two-step liquid-liquid extraction with ethyl acetate:acetonitrile (7:1), which had good extraction recovery. The LOQs of all mycotoxins ranged from 0.1 to 1 ng/mL. Intra-day accuracy ranged from 94 to 106%, and intra-day precision ranged from 1 to 12% for all mycotoxins. Inter-day accuracy and precision were 95-105% and 2-8%, respectively. The method was successfully applied to investigate the urine levels of 17 mycotoxins from 42 volunteers. Deoxynivalenol (DON, 0.97-9.88 ng/mL) was detected in 10 (24%) urine samples and zearalenone (ZEN, 0.13-1.11 ng/mL) in 2 (5%) urine samples.

Literature review and evaluation of biomarkers, matrices and analytical methods for chemicals selected in the research program Human Biomonitoring for the European Union (HBM4EU)

Humans are potentially exposed to a large amount of chemicals present in the environment and in the workplace. In the European Human Biomonitoring initiative (Human Biomonitoring for the European Union = HBM4EU), acrylamide, mycotoxins (aflatoxin B1, deoxynivalenol, fumonisin B1), diisocyanates (4,4'-methylenediphenyl diisocyanate, 2,4- and 2,6-toluene diisocyanate), and pyrethroids were included among the prioritized chemicals of concern for human health. For the present literature review, the analytical methods used in worldwide biomonitoring studies for these compounds were collected and presented in comprehensive tables, including the following parameter: determined biomarker, matrix, sample amount, work-up procedure, available laboratory quality assurance and quality assessment information, analytical techniques, and limit of detection. Based on the data presented in these tables, the most suitable methods were recommended. According to the paradigm of biomonitoring, the information about two different biomarkers of exposure was evaluated: a) internal dose = parent compounds and metabolites in urine and blood; and b) the biologically effective = dose measured as blood protein adducts. Urine was the preferred matrix used for deoxynivalenol, fumonisin B1, and pyrethroids (biomarkers of internal dose). Markers of the biological effective dose were determined as hemoglobin adducts for diisocyanates and acrylamide, and as serum-albumin-adducts of aflatoxin B1 and diisocyanates. The analyses and quantitation of the protein adducts in blood or the metabolites in urine were mostly performed with LC-MS/MS or GC-MS in the presence of isotope-labeled internal standards. This review also addresses the critical aspects of the application, use and selection of biomarkers. For future biomonitoring studies, a more comprehensive approach is discussed to broaden the selection of compounds.

Development and Validation of LC-Q-TOF-MS Methodology to Determine Mycotoxin Biomarkers in Human Urine

Mycotoxin contamination of foodstuffs is a health concern worldwide and monitoring human exposure to mycotoxins is a key concern. Most mycotoxins and their metabolites are excreted in urine, but a reliable detection method is required, considering the low levels present in this biological sample. The aim of this work is to validate a sensitive methodology capable of simultaneously determining ten targeted mycotoxins as well as detecting untargeted ones by using Liquid Chromatography coupled to Quadrupole Time of Flight Mass Spectrometry (LC-Q-TOF-MS). The targeted mycotoxins were: enniatin A, B, A1, and B1, beauvericine, aflatoxin B1, B2, G1 and G2, and ochratoxin A. Several extraction procedures such as liquid-liquid extraction, dilute and shoot, and QuEChERS were assessed. Finally, a modified simple QuEChERS extraction method was selected. Creatinine adjustment and matrix-matched calibration curves are required. The limit of detection and limit of quantification values ranged from 0.1 to 1.5 and from 0.3 to 5 ng/mL, respectively. Recoveries achieved were higher than 65% for all mycotoxins. Later, the method was applied to 100 samples of women's urine to confirm the applicability and determine their internal exposure. The untargeted mycotoxins most found were trichothecenes, zearalenones, and ochratoxins.

Simultaneous determination of 16 urinary metabolites of organophosphate flame retardants and organophosphate pesticides by solid phase extraction and ultra performance liquid chromatography coupled to tandem mass spectrometry

Organophosphate flame retardants (OPFRs) and organophosphate pesticides (OPPs), pertaining to organophosphate esters, are ubiquitous in environment and have been verified to pose noticeable risks to human health. To evaluate human exposures to OPFRs and OPPs, a fast and sensitive approach based on a solid phase extraction (SPE) followed by the ultra-high-performance liquid chromatography coupled to tandem mass spectrometry (UPLC-MS/MS) detection has been developed for the simultaneous analysis of multiple organophosphorus metabolites in urine. The method allows the identification and quantification of ten metabolites of the most common OPFRs and all six dialkylphosphates (DAPs) of OPPs concerning the population exposure characteristics. The method provided good linearities (R² = 0.998-0.999), satisfactory method detection limits (MDLs) (0.030-1.129 ng/mL) and only needed a small volume (200 μL) of urine. Recovery rates ranged 73.4-127.1% at three spiking levels (2, 10 and 25 ng/mL urine), with both intra- and inter-day precision less than 14%. The good correlations for DAPs in a cross-validation test with a previous gas chromatography-mass spectrometry (GC-MS) method and a good inter-laboratory agreement for several OPFR metabolites in a standard reference material (SRM 3673) re-enforced the precision and validity of our method. Finally, the established method was successfully applied to analyze 16 organophosphorus metabolites in 35 Chinese children's urine samples. Overall, by validating the method's sensitivity, accuracy, precision, reproducibility, etc., data reliability and robustness were ensured; and the satisfactory pilot application on real urine samples demonstrated feasibility and acceptability of this method for being implemented in large population-based studies.

High-Throughput Determination of Major Mycotoxins with Human Health Concerns in Urine by LC-Q TOF MS and Its Application to an Exposure Study

Human biomonitoring constitutes a suitable tool to assess exposure to toxins overcoming the disadvantages of traditional methods. Urine constitutes an accessible biological matrix in biomonitoring studies. Mycotoxins are secondary metabolites produced naturally by filamentous fungi that produce a wide range of adverse health effects. Thus, the determination of urinary mycotoxin levels is a useful tool for assessing the individual exposure to these food contaminants. In this study, a suitable methodology has been developed to evaluate the presence of aflatoxin B2 (AFB2), aflatoxin (AFG2), ochratoxin A (OTA), ochratoxin B (OTB), zearalenone (ZEA), and α-zearalenol (α-ZOL) in urine samples as exposure biomarkers. For this purpose, different extraction procedures, namely, the Solid Phase Extraction (SPE); Dispersive Liquid–Liquid Microextraction (DLLME); and Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) methods were assessed, followed by Liquid Chromatography coupled to Quadrupole Time of Flight Mass Spectrometry with Electrospray Ionization (LC-ESI-QTOF-MS) determination. Then, the proposed methodology was applied to determine mycotoxin concentrations in 56 human urine samples from volunteers and to estimate the potential risk of exposure. The results obtained revealed that 55% of human urine samples analyzed resulted positive for at least one mycotoxin. Among all studied mycotoxins, only AFB2, AFG2, and OTB were detected with incidences of 32, 41, and 9%, respectively, and levels in the range from <LOQ to 69.42 µg/L. Risk assessment revealed a potential health risk, obtaining MoE values < 10,000. However, it should be highlighted that few samples were contaminated, and that more data about mycotoxin excretion rates and their BMDL10 values are needed for a more accurate risk assessment.

Optimization of the QuEChERS-Based Analytical Method for Investigation of 11 Mycotoxin Residues in Feed Ingredients and Compound Feeds

Mycotoxins are toxic substances naturally produced by various fungi, and these compounds not only inflict economic damage, but also pose risks to human and animal health. The goal of the present study was to optimize the QuEChERS-based extraction and liquid chromatography–tandem mass spectrometry (LC–MS/MS) method for the analysis of 11 mycotoxins, such as aflatoxins (AFs), ochratoxin A (OTA), fumonisins (FBs), T-2 toxin, HT-2 toxin, zearalenone (ZEN), and deoxynivalenol (DON), commonly found in feed. The QuEChERS method, characterized by being “quick, easy, cheap, effective, rugged, and safe”, has become one of the most common extractions and clean-up procedures for mycotoxin analyses in food. Therefore, in this experiment, an optimal method for the analysis of 11 mycotoxins in feed was established by modifying the general QuEChERS method. In this process, it was confirmed that even if feed samples of different weights were extracted, the quantitative value of mycotoxins in the feed was not affected. To reduce matrix effects, 13C-labeled compounds and deuterium were used as internal standards. This optimized method was then applied in the determination of 11 mycotoxins in 736 feed ingredients and compound feeds obtained from South Korea. The results showed that the occurrence rates of FBs, ZEN, and DON were 59.4%, 38.0%, and 32.1%, respectively, and OTA, AFs, and T-2 toxin and HT-2 toxin were found in fewer than 1% of the 736 feeds. The mean concentration ranges of FBs, ZEN, and DON were 757–2387, 44–4552, and 248–9680 μg/kg, respectively. Among the samples in which DON and ZEN were detected, 10 and 12 samples exceeded the management recommendation standards presented by the Ministry of Agriculture, Food and Rural Affairs (MAFRA). However, when the detected concentrations of DON and ZEN were compared with guideline levels in foreign countries, such as the US, Japan, China, and the EU, the number of positive samples changed. In addition, the co-occurrence of mycotoxins in the feed was analyzed, and the results showed that 43.8% of the samples were contaminated with two or three mycotoxins, among which the co-occurrence rate of FBs, ZEN, and DON was the highest. In conclusion, these results suggest the need for stricter management standards for FBs, DON, and ZEN in South Korea, and emphasize the importance of the continuous monitoring of feeds.

Alternaria toxins-Still emerging?

Alternaria molds are known to cause the contamination of food with their secondary metabolites, a chemically very heterogeneous group of compounds. Yet, after decades of research on the occurrence and the toxicity of Alternaria toxins in academia, no regulation has been implemented yet, thus leaving these potential food contaminants in the status of so-called "emerging mycotoxins". However, research on this topic has been far from static, leading to the European Food Safety Authority repeatedly calling for more data on the occurrence and toxicity of genotoxic metabolites such as alternariol (AOH) and its monomethyl ether (AME). To give an overview on recent developments in the field, this comprehensive review summarizes published data and addresses current challenges arising from the chemical complexity of Alternaria's metabolome, mixture effects and the emergence of novel biological targets like cell membranes or the interaction with different receptors. Besides toxicodynamics, we review recent research on toxicokinetics, including the first in vivo studies which incorporated the rarely investigated-but highly genotoxic-perylene quinones. Furthermore, a particular focus lies on the advances of liquid chromatography/tandem mass spectrometry (LC-MS/MS)-based analytical tools for determining a broader spectrum of Alternaria toxins including modified/masked forms and assessing exposure via human biomonitoring (HBM).

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.

Development of a multi-mycotoxin LC-MS/MS method for the determination of biomarkers in pig urine

An LC-MS/MS method has been developed for the sensitive and selective determination of 35 mycotoxins (biomarkers of exposure) in pig urine samples. Sample preparation includes creatinine adjustment (with the developed LC-UV method) with enzymatic hydrolysis of pig urine samples followed by liquid-liquid (LLE) extraction. The LLE protocol, as well as enzymatic hydrolysis for indirect mycotoxin glucuronides determination, was optimized in this study. Additionally, two other sample preparation protocols were compared with the developed LLE method: immunoaffinity columns and solid-phase extraction cartridges (Oasis HLB). The detection and quantification of the biomarkers were performed using triple quadrupole mass spectrometry.The method was validated with regard to the guidelines specified by the EMEA (European Medicines Agency). The extraction recoveries were higher than 60% for 77% of the analytes studied, with the intra- and inter-day relative standard deviation being lower than 20% for most of the compounds at four different concentration levels. The limits of quantification ranged from 0.1 ng/mL for zearalenone and sterigmatocystin to 8 ng/mL for nivalenol. To the best knowledge of the authors, the matrix effect was evaluated for the first time in this study for six different urine samples, and the coefficient of variation was found to be lower than 15% for most analytes studied. Finally, the developed method was applied to analyse 56 pig urine samples. Deoxynivalenol (1-20 ng/mL), zearalenone (0.1-1.5 ng/mL) and ochratoxin A (1.5-15 ng/mL) were the main analytes detected in these samples. Moreover, the co-occurrence of alternariol monomethyl ether and alternariol in pig urine is reported herein for the first time.

Europium nanosphere-based fluorescence strip sensor for ultrasensitive and quantitative determination of fumonisin B1

Contamination of grains and related products by fumonisins (FBs) is increasingly becoming a serious food security issue. The aim of this work was to develop a europium fluorescent microsphere-based time-resolved fluorescence immunochromatographic assay (TRFICA) for FB₁ detection in different grains, including corn, corn flour, wheat, rice and brown rice. Standard curves for the five types of grain matrix were established, and showed good linearity (R² > 0.975), LOD of 8.26 μg kg^-1, and a wide working range of 13.81-1000 μg kg^-1. The recoveries of TRFICA for FB₁ detection ranged from 82.85-103.62% with variation coefficients of 1.92-15.33%. Two corn reference materials and other natural samples were tested using TRFICA. The same samples analyzed by liquid chromatography tandem mass spectrometry further confirmed the TRFICA results. The entire detection time of TRFICA was within 30 min. Thus, this developed TRFICA can be used for onsite detection and quantitation of FB₁ in grains.

Biomonitoring of Enniatin B1 and Its Phase I Metabolites in Human Urine: First Large-Scale Study

Enniatins (Enns) are mycotoxins produced by Fusarium spp. which are a fungus widely spread throughout cereals and cereal-based products. Among all the identified enniatins, Enn B1 stands as one of the most prevalent analogues in cereals in Europe. Hence, the aim of this study was to evaluate for the first time the presence of Enn B1 and its phase I metabolites in 300 human urine samples using an ultrahigh-performance liquid chromatography high resolution mass spectrometry (UHPLC-Q-Orbitrap HRMS) methodology. Enn B1 was detected in 94.3% of samples ranging from 0.007 to 0.429 ng/mL (mean value: 0.065 ng/mL). In accordance with previous in vitro and in vivo analysis, hydroxylated metabolites (78.0% samples) and carbonylated metabolites (66.0% samples) were tentatively identified as the major products. Results from this biomonitoring study point to a frequent intake of Enn B1 in the studied population, suggesting that in-depth toxicological studies are needed in order to understand the potential effects in humans.