Multi-mycotoxin analysis of finished grain and nut products using high-performance liquid chromatography-triple-quadrupole mass spectrometry

Optimization, Validation, and Application of Cleanup-Coupled Liquid Chromatography-Tandem Mass Spectrometry for the Simultaneous Analyses of 35 Mycotoxins and Their Derivatives in Cereals

Mycotoxins occur singly or as co-contaminants and are primarily present in carbohydrate-rich foods such as cereals and cereal-based products. To effectively monitor mycotoxin co-contamination in cereals and cereal-based products, the simultaneous analysis of mycotoxins and their derivatives is required. Therefore, we coupled cleanup with LC-MS/MS for the rapid and robust quantitation of 35 analytes in wheat samples, including ergot alkaloids (EAs), which are rarely included in such analyses. To investigate the effects of different mycotoxin types on adsorbents, various dispersive solid-phase extraction sorbents were evaluated; a C18 end-capped sorbent exhibited the most effective cleanup performance. The method was validated by analyzing samples fortified with the mycotoxins at three concentration levels. The results exhibited high linearity, high recoveries, and repeatability. The methodology was applied for commercial cereal samples. The cereal samples were found to be 74% contaminated, and two samples measured levels of EAs at 609.63 μg/kg and 294.93 μg/kg, exceeding the limits defined by the EU for rye milling products. These findings highlight the validity of our novel method and the necessity of continuously monitoring mycotoxin levels in cereals to ensure food safety.

Ergot Alkaloids on Cereals and Seeds: Analytical Methods, Occurrence, and Future Perspectives

Ergot alkaloids are secondary metabolites resulting from fungi of the genus Claviceps that have proven to be highly toxic. These mycotoxins commonly infect cereal crops such as wheat, rye, barley, and oats. Due to the increase worldwide consumption of cereal and cereal-based products, the presence of ergot alkaloids in food presents a concern for human safety. For this reason, it is essential to develop several analytical methods that allow the detection of these toxic compounds. This review compiles and discusses the most relevant studies and methods used in the detection and quantification of ergot alkaloids. Moreover, the decontamination techniques are also addressed, with special attention to sorting, cleaning, frying, baking, peeling, and ammonization methods, as they are the only ones already applied to ergot alkaloids.

Simultaneous Rapid Determination of Seven Alternaria Toxins in Tuberous Crops during Storage Using QuEChERS Coupled with Ultrahigh-Performance Liquid Chromatography-Tandem Mass Spectrometry

Robust and sensitive ultrahigh-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) combined with the quick, easy, cheap, effective, rugged, and safe (QuEChERS) method was applied for the detection of seven Alternaria toxins (ATs) in tuberous crops. The influence of tuber conditions (fresh, germinated, and moldy) during storage on the concentration of the seven ATs is also investigated. ATs were extracted with acetonitrile under acidic conditions and purified with a C₁₈ adsorbent. ATs were scanned with electrospray ionization (positive/negative ion) dynamic switching and detected in MRM mode. Calibration curve analysis results reveal good linear relationships in all toxin concentration ranges (R² > 0.99). The limit of detection and limit of quantification were 0.25-0.70 and 0.83-2.31 μg/kg, respectively. The average recoveries of the seven ATs were 83.2-104% with intra-/inter-day precision at 3.52-6.55% and 4.02-7.26%, respectively. The developed method provided adequate selectivity, sensitivity, and precision in detecting the seven ATs at trace levels, and dispensed with standard addition or matrix-matched calibration to compensate for matrix effects. ATs in the fresh, germinated, and moldy samples of tuberous crops in storage (taro, potato, sweet potato, yam, cassava) were analyzed with this method, and the concentrations were 2.01-14.51 μg/kg and significantly increased with storage duration. ALS was detected in most samples, whereas no quantities of ALT and ATX-I were detected. AME was often detected in combination with AOH in sweet potatoes. TeA and Ten were mostly detected in taro, potato, and yam. The established method could be used for the simultaneous detection and quantification of multicomponent toxins in elaborate matrices.

A Dilute-and-Shoot UHPLC-MS/MS Isotope Dilution Method for Simultaneous Determination and Confirmation of Eleven Mycotoxins in Dried Distillers Grains with Solubles

BACKGROUND

Natural contamination of mycotoxins in dried distiller's grains with solubles (DDGS) as a mainstream animal feed ingredient poses risk to animal health.

OBJECTIVE

A regulatory method was needed for the agency to simultaneously detect eleven mycotoxins of high regulatory priority in DDGS.

METHODS

Ten grams of DDGS sample were extracted twice with acetonitrile/water under mildly acidic condition. Two aliquots from the combined crude extract were taken and processed separately: (1) diluted 400-fold with solvent for analysis of deoxynivalenol and fumonisins B1 and B2; (2) pH adjusted to 7.5, then diluted 15.7-fold for analysis of aflatoxins B1, B2, G1, G2, ochratoxin A, zearalenone, and T-2 and HT-2 toxins. Uniformly-labelled 13C-isotopologues of these mycotoxins were added as internal standards to the diluted extracts for quantitative analysis by ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS). Results. The linear quantitation ranges (µg/kg) were: aflatoxin B1, B2, G1, and G2, 1.57 to 105; zearalenone, 16.3 to 1090; T-2 toxin, 3.14 to 208; HT-2 toxin, 48.2 to 3220; ochratoxin A, 0.47 to 31.4; deoxynivalenol, 240 to 16000; fumonisin B1 and B2, 320 to 21200. Accuracies for these analytes at each of three fortification levels range from 70.7% to 100%, with corresponding relative standard deviations between 1.4% to 10.5%. True recoveries were all higher than 83%.

CONCLUSIONS

This method was successfully validated to meet the agency's performance guidelines for regulatory methods.

HIGHLIGHTS

This method is easy, quick and robust to simultaneously quantify and confirm presence of eleven regulated mycotoxins in DDGS.

A critical review of analytical methods for ergot alkaloids in cereals and feed and in particular suitability of method performance for regulatory monitoring and epimer-specific quantification

Cereals and feed contaminated with ergot alkaloids (EAs) have been of concern for several decades. Nowadays, analysis of EAs is focused on ergometrine, ergotamine, ergosine, ergocristine, ergocryptine (a mixture of α- and β-isomers) and ergocornine and their related -inine epimers as listed in the European Commission Recommendation 2012/154/EU. Liquid chromatography with fluorescence detection has been used for quantification of EAs for decades whilst LC-MS has become the work-horse for quantification of EAs in the last decade. However, in LC-MS analysis matrix effects of different magnitudes exist for each EA epimer, especially ergometrine/ergometrinine, even after different clean-up procedures. This leads to an underestimation or overestimation of EAs levels. Moreover, isotopic labelled standards for EAs are still not available in the market. This review aims to provide background information on different analytical methods, discuss their advantages and disadvantages and possible advancement. Moreover, the method performance requirements to support forthcoming regulations are also discussed.

Suitability of High-Resolution Mass Spectrometry for Routine Analysis of Small Molecules in Food, Feed and Water for Safety and Authenticity Purposes: A Review

During the last decade, food, feed and environmental analysis using high-resolution mass spectrometry became increasingly popular. Recent accessibility and technological improvements of this system make it a potential tool for routine laboratory work. However, this kind of instrument is still often considered a research tool. The wide range of potential contaminants and residues that must be monitored, including pesticides, veterinary drugs and natural toxins, is steadily increasing. Thanks to full-scan analysis and the theoretically unlimited number of compounds that can be screened in a single analysis, high-resolution mass spectrometry is particularly well-suited for food, feed and water analysis. This review aims, through a series of relevant selected studies and developed methods dedicated to the different classes of contaminants and residues, to demonstrate that high-resolution mass spectrometry can reach detection levels in compliance with current legislation and is a versatile and appropriate tool for routine testing.

A Review: Sample Preparation and Chromatographic Technologies for Detection of Aflatoxins in Foods

As a class of mycotoxins with regulatory and public health significance, aflatoxins (e.g., aflatoxin B1, B2, G1 and G2) have attracted unparalleled attention from government, academia and industry due to their chronic and acute toxicity. Aflatoxins are secondary metabolites of various Aspergillus species, which are ubiquitous in the environment and can grow on a variety of crops whereby accumulation is impacted by climate influences. Consumption of foods and feeds contaminated by aflatoxins are hazardous to human and animal health, hence the detection and quantification of aflatoxins in foods and feeds is a priority from the viewpoint of food safety. Since the first purification and identification of aflatoxins from feeds in the 1960s, there have been continuous efforts to develop sensitive and rapid methods for the determination of aflatoxins. This review aims to provide a comprehensive overview on advances in aflatoxins analysis and highlights the importance of sample pretreatments, homogenization and various cleanup strategies used in the determination of aflatoxins. The use of liquid-liquid extraction (LLE), supercritical fluid extraction (SFE), solid phase extraction (SPE) and immunoaffinity column clean-up (IAC) and dilute and shoot for enhancing extraction efficiency and clean-up are discussed. Furthermore, the analytical techniques such as gas chromatography (GC), liquid chromatography (LC), mass spectrometry (MS), capillary electrophoresis (CE) and thin-layer chromatography (TLC) are compared in terms of identification, quantitation and throughput. Lastly, with the emergence of new techniques, the review culminates with prospects of promising technologies for aflatoxin analysis in the foreseeable future.

HPLC-MS/MS Method for the Detection of Selected Toxic Metabolites Produced by Penicillium spp. in Nuts

Penicillium spp. are emerging as producers of mycotoxins and other toxic metabolites in nuts. A HPLC-MS/MS method was developed to detect 19 metabolites produced by Penicillium spp. on chestnuts, hazelnuts, walnuts and almonds. Two extraction methods were developed, one for chestnuts and one for the other three nuts. The recovery, LOD, LOQ and matrix effect were determined for each analyte and matrix. Correlation coefficients were always >99.99%. In walnuts, a strong signal suppression was observed for most analytes and patulin could not be detected. Six strains: Penicillium bialowiezense, P. brevicompactum, P. crustosum, P. expansum, P. glabrum and P. solitum, isolated from chestnuts, were inoculated on four nuts. Chestnuts favored the production of the largest number of Penicillium toxic metabolites. The method was used for the analysis of 41 commercial samples: 71% showed to be contaminated by Penicillium-toxins. Cyclopenin and cyclopenol were the most frequently detected metabolites, with an incidence of 32% and 68%, respectively. Due to the risk of contamination of nuts with Penicillium-toxins, future studies and legislation should consider a larger number of mycotoxins.

Development and Validation of a QuEChERS-Based Liquid Chromatography Tandem Mass Spectrometry Multi-Method for the Determination of 38 Native and Modified Mycotoxins in Cereals

Here, a reliable and sensitive method for the determination of 38 (modified) mycotoxins was developed. Using a QuEChERS-based extraction method [acetonitrile/water/formic acid (75:20:5, v/v/v)], followed by two runs of high performance liquid chromatography tandem mass spectrometry with different conditions, relevant mycotoxins in cereals were analyzed. The method was validated according to the performance criteria defined by the European Commission (EC) in Commission Decision no. 657/2002. Limits of quantification ranged from 0.05 to 150 μg/kg. Good linearity (R² > 0.99), recovery (61-120%), repeatability (RSDr < 15%), and reproducibility (RSDR < 20%) were obtained for most mycotoxins. However, validation results for Alternaria toxins and fumonisins were unsatisfying. Matrix effects (-69 to +59%) were compensated for using standard addition. Application on reference materials gave correct results while analysis of samples from local retailers revealed contamination, especially with deoxynivalenol, deoxynivalenol-3-glucoside, fumonisins, and zearalenone, in concentrations up to 369, 58, 1002, and 21 μg/kg, respectively.

Evaluation of High-Resolution Mass Spectrometry for the Quantitative Analysis of Mycotoxins in Complex Feed Matrices

The selective and sensitive analysis of mycotoxins in highly complex feed matrices is a great challenge. In this study, the suitability of Orbitrap^TM-based high-resolution mass spectrometry (HRMS) for routine mycotoxin analysis in complex feeds was demonstrated by the successful validation of a full MS/data-dependent MS/MS acquisition method for the quantitative determination of eight Fusarium mycotoxins in forage maize and maize silage according to the Commission Decision 2002/657/EC. The required resolving power for accurate mass assignments (<5 ppm) was determined as 35,000 full width at half maximum (FWHM) and 70,000 FWHM for forage maize and maize silage, respectively. The recovery (R_A), intra-day precision (RSD_r), and inter-day precision (RSD_R) of measurements were in the range of 94 to 108%, 2 to 16%, and 2 to 12%, whereas the decision limit (CCα) and the detection capability (CCβ) varied from 11 to 88 µg/kg and 20 to 141 µg/kg, respectively. A set of naturally contaminated forage maize and maize silage samples collected in northern Germany in 2017 was analyzed to confirm the applicability of the HRMS method to real samples. At least four Fusarium mycotoxins were quantified in each sample, highlighting the frequent co-occurrence of mycotoxins in feed.

Development and comparison of single-step solid phase extraction and QuEChERS clean-up for the analysis of 7 mycotoxins in fruits and vegetables during storage by UHPLC-MS/MS

A robust and sensitive UHPLC-MS/MS method was developed for the analysis of seven mycotoxins in fruits and vegetables. The variations of seven mycotoxins concentrations during storage were also determined for the first time. Solid phase extraction (SPE) and QuEChERS clean-up were compared, and extraction was finally performed with acetonitrile under acidic conditions followed by HLB SPE purification. Seven mycotoxins were separated on a C18 column by gradient elution, scanned by ESI⁺ and ESI^- dynamic switching and detected with MRM mode. LOD and LOQ, matrix effect, accuracy and precision of the developed method were investigated. Results were linear in their concentration ranges for all mycotoxins with R² being greater than 0.999. LODs and LOQs were ranged from 0.05 to 3.0 μg/kg and 0.2 to 10.0 μg/kg, respectively. Average recoveries were between 81.1% and 116% with intraday- and interday-precision being in the ranges of 3.0-6.2% and 4.2-6.1%, respectively. The validated method provides sufficient selectivity, sensitivity and accuracy to screen for seven mycotoxins at trace levels, without using standard addition or matrix-matched calibration to compensate for matrix effects. The method was successfully applied for mycotoxins analysis in fruits and vegetables. None were detected in fresh samples, but AOH and AME were detected in strawberry, and TeA was detected in tomato fruits during long-term storage. Their concentrations were in the range of 3.6-165.3 μg/kg from 3 days to 60 days and significantly increased along with storage time.

Rapid Assessment of the Toxicity of Fungal Compounds Using Luminescent Vibrio qinghaiensis sp. Q67

Most tropical fruits after harvest are very perishable because of fungal infection. Since some pathogenic fungi can produce hazardous compounds such as mycotoxins, novel rapid and effective methods to assess those hazardous compounds are urgently needed. Herein we report that Vibrio qinghaiensis sp. Q67, a luminescent bacterium, can be used to rapidly assess the toxicities of mycotoxins and cultures from mycotoxin-producing pathogens. A good correlation (R² > 0.98) between concentrations of the mycotoxins (fumonisin B1, deoxynivalenol, zearalenone, ochratoxin A, patulin, and citrinin) and the luminous intensity of V. qinghaiensis sp. Q67 was obtained. Furthermore, significant correlations (R² > 0.96) between the amount of mycotoxin and the luminous intensity from the cultures of 10 major mycotoxin-producing pathogens were also observed. In addition, Fusarium proliferatum (half-maximal inhibitory concentration (IC₅₀) = 17.49%) exhibited greater luminescence suppression than Fusarium semitectum (IC₅₀ = 92.56%) or Fusarium oxysporum (IC₅₀ = 28.61%), which was in agreement with the existing higher levels of fumonisin B1, fumonisin B2, and deoxynivalenol, which were measured by high-performance liquid chromatography-tandem mass spectrometry. These results suggest that V. qinghaiensis sp. Q67 is a promising alternative for the rapid evaluation of the toxicity of fungal mycotoxins.

Study of the genetic diversity of the aflatoxin biosynthesis cluster in Aspergillus section Flavi using insertion/deletion markers in peanut seeds from Georgia, USA

Aflatoxins are among the most powerful carcinogens in nature. The major aflatoxin-producing fungi are Aspergillus flavus and A. parasiticus. Numerous crops, including peanut, are susceptible to aflatoxin contamination by these fungi. There has been an increased use of RNA interference (RNAi) technology to control phytopathogenic fungi in recent years. In order to develop molecular tools targeting specific genes of these fungi for the control of aflatoxins, it is necessary to obtain their genome sequences. Although high-throughput sequencing is readily available, it is still impractical to sequence the genome of every isolate. Thus, in this work, the authors proposed a workflow that allowed prescreening of 238 Aspergillus section Flavi isolates from peanut seeds from Georgia, USA. The aflatoxin biosynthesis cluster (ABC) of the isolates was fingerprinted at 25 InDel (insertion/deletion) loci using capillary electrophoresis. All isolates were tested for aflatoxins using ultra-high-performance liquid chromatography. The neighbor-joining, three-dimension (3D) principal coordinate, and Structure analyses revealed that the Aspergillus isolates sampled consisted of three main groups determined by their capability to produce aflatoxins. Group I comprised 10 non-aflatoxigenic A. flavus; Group II included A. parasiticus; and Group III included mostly aflatoxigenic A. flavus and the three non-aflatoxigenic A. caelatus. Whole genomes of 10 representative isolates from different groups were sequenced. Although InDels in Aspergillus have been used by other research groups, this is the first time that the cluster analysis resulting from fingerprinting was followed by whole-genome sequencing of representative isolates. In our study, cluster analysis of ABC sequences validated the results obtained with fingerprinting. This shows that InDels used here can predict similarities at the genome level. Our results also revealed a relationship between groups and their capability to produce aflatoxins. The database generated of Aspergillus spp. can be used to select target genes and assess the effectiveness of RNAi technology to reduce aflatoxin contamination in peanut.

Towards the development of innovative multi-mycotoxin reference materials as promising metrological tool for emerging and regulated mycotoxin analyses

The interest in LC-MS/MS multi-mycotoxin methods unveiled an urgent need for multi-mycotoxin reference material. A multi-fusariotoxin, including deoxynivalenol (DON); zearalenone (ZEN); T-2 toxin (T-2); HT-2 toxin (HT-2); enniatin A, A1, B, and B1 (ENNs); and beauvericin (BEA), contaminated wheat flour was obtained by inoculation Fusarium spp. strains. The candidate material has successfully passed the homogeneity test and submitted to an international interlaboratory study achieved by 19 laboratories from 11 countries using their routine analytical method. The dispersion of the results for ZEN and BEA did not allow the derivation of reliable consensus values, while the assignment was only possible for DON, HT-2, T-2, and ENN A. No link was found between the methods used by the participants and the results. Significant changes in dry matter contents (≥±1.4 % of the initial dry matter) and significant changes in ergosterol contents (≥±10 %) did not occur. Using the mycotoxin contents in wheat flour stored at -80 °C as reference values, statistically significant decreases were observed only for T-2 contents at +24 °C, in contrast to the storage at -20 and +4 °C. For the other involved toxins, the candidate material was found to be stable at -20, +4, or +24 °C. Based on the T-2 decreases, a shelf life of 6 years was derived from isochronous study when the material is kept at -20 °C. At room temperature (e.g., +24 °C) or higher, this time validity drastically decreases down to 6 months. The development of this metrological tool is an important step towards food and feed quality control using multi-mycotoxin analyses. In vivo animal experiments using multi-mycotoxin-contaminated feeds dealing with the carryover or mitigation could further benefit from the methodology of this work.

Multi-mycotoxin Analysis of Finished Grain and Nut Products Using Ultrahigh-Performance Liquid Chromatography and Positive Electrospray Ionization-Quadrupole Orbital Ion Trap High-Resolution Mass Spectrometry

Ultrahigh-performance liquid chromatography using positive electrospray ionization and quadrupole orbital ion trap high-resolution mass spectrometry was evaluated for analyzing mycotoxins in finished cereal and nut products. Optimizing the orbital ion trap mass analyzer in full-scan mode using mycotoxin-fortified matrix extracts gave mass accuracies, δM, of < ± 2.0 ppm at 70,000 full width at half maximum (FWHM) mass resolution (RFWHM). The limits of quantitation were matrix- and mycotoxin-dependent, ranging from 0.02 to 11.6 μg/kg. Mean recoveries and standard deviations for mycotoxins from acetonitrile/water extraction at their relevant fortification levels were 91 ± 10, 94 ± 10, 98 ± 12, 91 ± 13, 99 ± 15, and 93 ± 17% for corn, rice, wheat, almond, peanut, and pistachio, respectively. Nineteen mycotoxins with concentrations ranging from 0.3 (aflatoxin B1 in peanut and almond) to 1175 μg/kg (fumonisin B1 in corn flour) were found in 35 of the 70 commercial grain and nut samples surveyed. Mycotoxins could be identified at δM < ± 5 ppm by identifying the precursor and product ions in full-scan MS and data-dependent MS/MS modes. This method demonstrates a new analytical approach for monitoring mycotoxins in finished grain and nut products.

Aflatoxins in cereals: worldwide occurrence and dietary risk assessment

The worldwide occurrence of aflatoxins (AFB1, AFB2, AFG1, AFG2), genotoxic mycotoxins, in raw maize, rice, sorghum and wheat samples collected since the year 2000 was evaluated using published data and occurrence data from the GEMS/Food database (https://extranet.who.int/gemsfood). Dietary risk assessments were conducted using GEMS/Food total aflatoxin occurrence and food consumption data obtained from the 17 Cluster Diets. Risk characterisation arising from aflatoxin exposure was conducted using both cancer risk and margin of exposure (MOE) approaches. A total of 89 publications were retrieved from the literature, reporting data related to 18,097 samples, of which 37.6% were positive for at least one aflatoxin. The total upper bound (UB) mean for all samples analysed was 13.6 μg/kg, and was higher for rice (24.6 μg/kg) and sorghum (25.9 μg/kg). Of data related to the analysis of 4,536 samples reported to GEMS/Food database, 12.7% were positive for at least one aflatoxin. The total UB mean was 1.9 μg/kg, and was higher for rice (2.4 μg/kg) and maize (1.6 μg/kg). Total intakes ranged from 3.0 ng/kg bw/day (Cluster C11) to 17.1 ng/kg bw/day (Cluster C09). On average, the consumption of rice contributed to 41.6% of the total aflatoxin intake in all clusters, followed by wheat (35.4%), maize (21.2%) and sorghum (1.8%). The lowest cancer risk was found in cluster C11 (0.057 cancers/year/105 individuals), and the highest in cluster C09 (0.467 cancers/year/105 individuals). MOE ranged from 56 (C11) to 10 (C09), indicating a potential risk to consumers. These results highlight the need for continuous action by health authorities to decrease aflatoxin contamination in cereals, as they are staple foods in diets worldwide. These actions include the enforcement of code of practices at the national level and the establishment of maximum contamination levels by the Codex System.

Analysis of Ergot Alkaloids

The principles and application of established and newer methods for the quantitative and semi-quantitative determination of ergot alkaloids in food, feed, plant materials and animal tissues are reviewed. The techniques of sampling, extraction, clean-up, detection, quantification and validation are described. The major procedures for ergot alkaloid analysis comprise liquid chromatography with tandem mass spectrometry (LC-MS/MS) and liquid chromatography with fluorescence detection (LC-FLD). Other methods based on immunoassays are under development and variations of these and minor techniques are available for specific purposes.

A method for simultaneous determination of 20 Fusarium toxins in cereals by high-resolution liquid chromatography-Orbitrap mass spectrometry with a pentafluorophenyl column

A high-resolution liquid chromatography-Orbitrap mass spectrometry (LC-Orbitrap MS) method was developed for simultaneous determination of 20 Fusarium toxins (nivalenol, fusarenon-X, deoxynivalenol, 3-acetyl deoxynivalenol, 15-acetyl deoxynivalenol, HT-2 toxin, T-2 toxin, neosolaniol, diacetoxyscirpenol, fumonisin B1, fumonisin B2, fumonisin B3, fumonisin A1, fumonisin A2, fumonisin A3, zearalenone, α-zearalenol, β-zearalenol, α-zearalanol, and β-zearalanol) in cereals. The separation of 20 Fusarium toxins with good peak shapes was achieved using a pentafluorophenyl column, and Orbitrap MS was able to detect accurately from cereal matrix components within ±0.77 ppm. The samples were prepared using a QuEChERS kit for extraction and a multifunctional cartridge for purification. The linearity, repeatability, and recovery of the method were >0.9964, 0.8%-14.7%, and 71%-106%, respectively. Using this method, an analysis of 34 commercially available cereals detected the presence of deoxynivalenol, 15-acetyl deoxynivalenol, fumonisin B1, fumonisin B2, fumonisin B3, fumonisn A1, fumonisin A2, fumonisin A3, and zearalenone in corn samples with high concentration and frequency. Trichothecenes was detected from wheat samples with high frequency; in particular, the concentration of deoxynivalenol was high. Conversely, α-zearalenol, β-zearalenol, α-zearalanol, and β-zearalanol were not detected in any of the samples.

Multi-mycotoxin screening reveals separate occurrence of aflatoxins and ochratoxin a in Asian rice

The determination of important regulated mycotoxins in rice has been reported previously but not in the individual matrix of white, brown, red, and basmati rice with respect to the matrix effect, recovery, and stability. A total of 190 Asian rices were examined for regulated mycotoxin contamination by the LC-ESI-MS/MS method. Significant variation (p < 0.05) in the matrix effect was observed for fumonisins. Methanol improved the limits of detection (LOD) for HT-2 from 50 μg/kg to 2.3 μg/kg by promoting ionization efficiency of the ammonium-adduct. LOD and limits of quantitation ranged from 0.1 to 18 μg/kg and 0.2-31 μg/kg, respectively. All analytes degraded by more than 50% on storage, except fumonisins. Acetic acid (1%) provided significant improvement (p < 0.05) in recovery for all analytes in selected white rice from Thailand and China. Mean recovery ranged from 70 to 120%. RSD values were lower than 15% for all analytes. Five AFB1 and single OTA positive samples were detected. No correlation between mycotoxin contamination and rice species (r = 0) exists.

Determining mycotoxins in baby foods and animal feeds using stable isotope dilution and liquid chromatography tandem mass spectrometry

We developed a stable isotope dilution assay with liquid chromatography tandem mass spectrometry (LC-MS/MS) to determine multiple mycotoxins in baby foods and animal feeds. Samples were fortified with [(13)C]-uniformly labeled mycotoxins as internal standards ([(13)C]-IS) and prepared by solvent extraction (50% acetonitrile in water) and filtration, followed by LC-MS/MS analysis. Mycotoxins in each sample were quantitated with the corresponding [(13)C]-IS. In general, recoveries of aflatoxins (2-100 ng/g), deoxynivalenol, fumonisins (50-2000 ng/g), ochratoxin A (20-1000 ng/kg), T-2 toxin, and zearalenone (40-2000 ng/g) in tested matrices (grain/rice/oatmeal-based formula, animal feed, dry cat/dog food) ranged from 70 to 120% with relative standard deviations (RSDs) <20%. The method provides sufficient selectivity, sensitivity, accuracy, and reproducibility to screen for aflatoxins at ng/g concentrations and deoxynivalenol and fumonisins at low μg/g concentrations in baby foods and animal feeds, without using conventional standard addition or matrix-matched calibration standards to correct for matrix effects.

Combining the quick, easy, cheap, effective, rugged and safe approach and clean-up by immunoaffinity column for the analysis of 15 mycotoxins by isotope dilution liquid chromatography tandem mass spectrometry

Optimization and validation of a multi-mycotoxin method by LC-MS/MS is presented. The method covers the EU-regulated mycotoxins (aflatoxins, fumonisins, ochratoxin A, deoxynivalenol, zearalenone, T-2 and HT-2), as well as nivalenol and 3- and 15-acetyldeoxynivalenol for analysis of cereals, cocoa, oil, spices, infant formula, coffee and nuts. The proposed procedure combines two clean-up strategies: First, a generic preparation suitable for all mycotoxins based on the QuEChERS (for quick, easy, cheap, effective, rugged and safe) protocol. Second, a specific clean-up devoted to aflatoxins and ochratoxin A using immunoaffinity column (IAC) clean-up. Positive identification of mycotoxins in matrix was conducted according to the confirmation criteria defined in EU Commission Decision 2002/657/EC while quantification was performed by isotopic dilution using (13)C-labeled mycotoxins as internal standards. Limits of quantification were at or below the maximum levels set in the EC/1886/2006 document for all mycotoxin/matrix combinations under regulation. In particular, the inclusion of an IAC step allowed achieving LOQs as low as 0.05 and 0.25μg/kg in cereals for aflatoxins and ochratoxin A, respectively. Other performance parameters like linearity [(r)(2)>0.99], recovery [71-118%], precision [(RSDr and RSDiR)<33%], and trueness [78-117%] were all compliant with the analytical requirements stipulated in the CEN/TR/16059 document. Method ruggedness was proved by a verification process conducted by another laboratory.

Developments in mycotoxin analysis: an update for 2012-2013

This review highlights developments in mycotoxin analysis and sampling over a period between mid-2012 and mid-2013. It covers the major mycotoxins: aflatoxins, Alternaria toxins, ergot alkaloids, fumonisins, ochratoxins, patulin, trichothecenes and zearalenone. A wide range of analytical methods for mycotoxin determination in food and feed were developed last year, in particular immunochemical methods and liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS)-based methods. After a section on sampling and sample preparation, due to the rapid spread and developments in the field of LC-MS/MS multimycotoxin methods, a separate section has been devoted to this area of research. It is followed by a section on mycotoxins in botanicals and spices, before continuing with the format of previous reviews in this series with dedicated sections on method developments for the individual mycotoxins.

Non-linear relationships between aflatoxin B₁ levels and the biological response of monkey kidney vero cells

Aflatoxin-producing fungi contaminate food and feed during pre-harvest, storage and processing periods. Once consumed, aflatoxins (AFs) accumulate in tissues, causing illnesses in animals and humans. Most human exposure to AF seems to be a result of consumption of contaminated plant and animal products. The policy of blending and dilution of grain containing higher levels of aflatoxins with uncontaminated grains for use in animal feed implicitly assumes that the deleterious effects of low levels of the toxins are linearly correlated to concentration. This assumption may not be justified, since it involves extrapolation of these nontoxic levels in feed, which are not of further concern. To develop a better understanding of the significance of low dose effects, in the present study, we developed quantitative methods for the detection of biologically active aflatoxin B₁ (AFB1) in Vero cells by two independent assays: the green fluorescent protein (GFP) assay, as a measure of protein synthesis by the cells, and the microculture tetrazolium (MTT) assay, as a measure of cell viability. The results demonstrate a non-linear dose-response relationship at the cellular level. AFB1 at low concentrations has an opposite biological effect to higher doses that inhibit protein synthesis. Additional studies showed that heat does not affect the stability of AFB1 in milk and that the Vero cell model can be used to determine the presence of bioactive AFB1 in spiked beef, lamb and turkey meat. The implication of the results for the cumulative effects of low amounts of AFB1 in numerous foods is discussed.