Determination of zearalenone in grains by high-performance liquid chromatography-tandem mass spectrometry after solid-phase extraction with RP-18 columns or immunoaffinity columns

Molecularly Imprinted Polymer as Selective Sorbent for the Extraction of Zearalenone in Edible Vegetable Oils

A method based on the selective extraction of zearalenone (ZON) from edible vegetable oils using molecularly imprinted polymer (MIP) has been developed and validated. Ultra-high-pressure liquid chromatography coupled with a fluorescence detection system was employed for the detection of zearalenone. The method was applied to the analysis of zearalenone in maize oil samples spiked at four concentration levels within the maximum permitted amount specified by the European Commission Regulation (EC) No. 1126/2007. As a result, the proposed methodology provided high recoveries (>72%) with good linearity (R2 > 0.999) in the range of 10-2000 μg/kg and a repeatability relative standard deviation below 1.8%. These findings meet the analytical performance criteria specified by the European Commission Regulation No. 401/2006 and reveal that the proposed methodology can be successfully applied for monitoring zearalenone at trace levels in different edible vegetable oils. A comparison of MIP behavior with the ones of QuEChERS and liquid-liquid extraction was also performed, showing higher extraction rates and precision of MIP. Finally, the evolution of ZON contamination during the maize oil refining process was also investigated, demonstrating how the process is unable to completely remove (60%) ZON from oil samples.

Formation Ratios of Zearalanone, Zearalenols, and Zearalanols versus Zearalenone during Incubation of Fusarium semitectum on Sorghum and Ratios in Naturally Contaminated Sorghum

We incubated Fusarium semitectum on sorghum and measured the production of zearalenone (ZEN) and ZEN-related compounds (zearalanone (ZAN), α-zearalenol (α-ZEL), β-zearalenol (β-ZEL), α-zearalanol (α-ZAL) and β-zearalanol (β-ZAL)) in the culture by LC-MS. Of the five ZEN-related compounds, ZAN and β-ZEL were mainly detected. The concentrations of ZEN and the five ZEN-related compounds increased until 9 days after incubation and then increased slightly or stayed constant between days 9 and 15. The ratios of α-ZEL, β-ZEL, α-ZAL and β-ZAL to ZEN decreased in a similar manner after 7 days, whereas the ratio of ZAN to ZEN remained constant after 5 days. Analysis of naturally contaminated sorghum by LC-MS/MS revealed that the production ratio of α-ZEL to ZEN was inconsistent with that of our in vitro incubation analysis. The results indicate that ZAN might not be suitable for use as an internal standard.

Simultaneous determination of deoxynivalenol, and 15- and 3-acetyldeoxynivalenol in cereals by HPLC-UV detection

Fusarium head blight is an important cereal crop disease, which not only causes yield losses but also mycotoxin contamination in wheat and other cereal grains. Developing an accurate, rapid and efficient assay is critical to minimise the risk of Fusarium mycotoxins for human and animal health. In this study, HPLC with UV detection was used to separate and quantify deoxynivalenol, 15-acetyldeoxynivalenol and 3-acetyldeoxynivalenol in cereals. Samples were extracted with water, and the extracting solution was precipitated by adding an equal volume of ethanol followed by solid-phase extraction. The analytes were separated on a reversed-phase C18 column by a mobile phase composed of acetonitrile and 1 mM H3PO4 with gradient elution. 15- and 3-acetyldeoxynivalenol showed effective baseline separation. All analytes were well-resolved from matrix co-extractives and detected at 224 nm. The results showed good linearity of calibration curves (R2 ranged from 0.997 to 0.999) and excellent precision for inter- and intra-day determinations. Average recovery rates for the tested matrices ranged from 71 to 92%. The limits of detection and quantification ranged from 16 to 25 ng/g and 48 to 60 ng/g, respectively. The results indicate that the feasibility and practicality of the presented LC-UV method are excellent and that the method is suitable for routine analysis of DON and its acetyl derivatives in cereal grains.

Determination of zearalenone and its metabolites in urine and tissue samples of cow and pig by LC-MS/MS

For the sensitive and selective determination of zeranol, taleranol, α-zearalenol, β-zearalenol and zearalenone in animal urine and tissue a LC-MS/MS method has been developed. Sample preparation included extraction of meat samples and enzymatic digest of urine samples followed by solid-phase extraction with RP-18 columns for sample clean-up. Mass spectrometric determination was carried out with an atmospheric pressure chemical ionisation interface (APCI) in the multi-reaction monitoring mode (MRM). Using the negative ion mode detection limits between 0.1 and 0.5 ppb and determination limits between 0.5 and 1 ppb could be achieved. With zearalanone as internal standard, a linear range between 0.5 (1.0) and 100 ppb in urine samples (cow; pig) and between 1 and 100 ppb in meat samples (cow, calf, pig) could be established. Depending on the biological matrix and analyte standard deviations were below 8.2 %, with recovery rates between 86 and 102 % in spiked samples. The applicability of the method was demonstrated via several contaminated cow and pig urine samples.

Fungal and bacterial metabolites in commercial poultry feed from Nigeria

Metabolites of toxigenic fungi and bacteria occur as natural contaminants (e.g. mycotoxins) in feedstuffs making them unsafe to animals. The multi-toxin profiles in 58 commercial poultry feed samples collected from 19 districts in 17 states of Nigeria were determined by LC/ESI-MS/MS with a single extraction step and no clean-up. Sixty-three (56 fungal and seven bacterial) metabolites were detected with concentrations ranging up to 10,200 µg kg⁻¹ in the case of aurofusarin. Fusarium toxins were the most prevalent group of fungal metabolites, whereas valinomycin occurred in more than 50% of the samples. Twelve non-regulatory fungal and seven bacterial metabolites detected and quantified in this study have never been reported previously in naturally contaminated stored grains or finished feed. Among the regulatory toxins in poultry feed, aflatoxin concentrations in 62% of samples were above 20 µg kg⁻¹, demonstrating high prevalence of unsafe levels of aflatoxins in Nigeria. Deoxynivalenol concentrations exceeded 1000 µg kg⁻¹ in 10.3% of samples. Actions are required to reduce the consequences from regulatory mycotoxins and understand the risks of the single or co-occurrence of non-regulatory metabolites for the benefit of the poultry industry.

Metabolism of zearalenone in the course of beer fermentation

Zearalenone (ZON) is a mycotoxin with estrogenic activity, produced by members of Fusarium species, and is found worldwide in a number of cereal crops. It is known to have four active metabolites (α-zearalenol (α-ZOL), β-zearalenol (β-ZOL), α-zearalanol (α-ZAL), and β-zearalanol (β-ZAL)). A highly sensitive analytical method using liquid chromatography/tandem mass spectrometry using electrospray ionization (LC-ESI-MS/MS) has been established and validated in order to analyze ZON and its metabolites in beer and malt samples. The metabolism of ZON in the course of beer fermentation was further characterized using the artificially contaminated wort by this established method. In the fermented sample, 85.9% of ZON was converted to β-ZOL, which has lower estrogenic activity than that of ZON. These findings indicate that the health risk to humans due to ZON in beer is reduced during the fermentation process.

Phenolics: occurrence and immunochemical detection in environment and food

Phenolic compounds may be of natural or anthropogenic origin and be present in the environment as well as in food. They comprise a large and diverse group of compounds that may be either beneficial or harmful for consumers. In this review first a non-exhausting overview of interesting phenolics is given, in particular with regards to their presence in environment and food. For some of these compounds, beneficial, toxicological and/or optionally endocrine disrupting activities will be presented. Further, immunochemical detection and/or isolation methods developed will be discussed, including advantages and disadvantages thereof in comparison with conventional analytical methods such as HPLC, GC, MS. A short overview of new sensor-like methods will also be included for present and future application.

An overview of conventional and emerging analytical methods for the determination of mycotoxins

Mycotoxins are a group of compounds produced by various fungi and excreted into the matrices on which they grow, often food intended for human consumption or animal feed. The high toxicity and carcinogenicity of these compounds and their ability to cause various pathological conditions has led to widespread screening of foods and feeds potentially polluted with them. Maximum permissible levels in different matrices have also been established for some toxins. As these are quite low, analytical methods for determination of mycotoxins have to be both sensitive and specific. In addition, an appropriate sample preparation and pre-concentration method is needed to isolate analytes from rather complicated samples. In this article, an overview of methods for analysis and sample preparation published in the last ten years is given for the most often encountered mycotoxins in different samples, mainly in food. Special emphasis is on liquid chromatography with fluorescence and mass spectrometric detection, while in the field of sample preparation various solid-phase extraction approaches are discussed. However, an overview of other analytical and sample preparation methods less often used is also given. Finally, different matrices where mycotoxins have to be determined are discussed with the emphasis on their specific characteristics important for the analysis (human food and beverages, animal feed, biological samples, environmental samples). Various issues important for accurate qualitative and quantitative analyses are critically discussed: sampling and choice of representative sample, sample preparation and possible bias associated with it, specificity of the analytical method and critical evaluation of results.

Mycotoxin analysis: an update

Mycotoxin contamination of cereals and related products used for feed can cause intoxication, especially in farm animals. Therefore, efficient analytical tools for the qualitative and quantitative analysis of toxic fungal metabolites in feed are required. Current methods usually include an extraction step, a clean-up step to reduce or eliminate unwanted co-extracted matrix components and a separation step with suitably specific detection ability. Quantitative methods of analysis for most mycotoxins use immunoaffinity clean-up with high-performance liquid chromatography (HPLC) separation in combination with UV and/or fluorescence detection. Screening of samples contaminated with mycotoxins is frequently performed by thin layer chromatography (TLC), which yields qualitative or semi-quantitative results. Nowadays, enzyme-linked immunosorbent assays (ELISA) are often used for rapid screening. A number of promising methods, such as fluorescence polarization immunoassays, dipsticks, and even newer methods such as biosensors and non-invasive techniques based on infrared spectroscopy, have shown great potential for mycotoxin analysis. Currently, there is a strong trend towards the use of multi-mycotoxin methods for the simultaneous analysis of several of the important Fusarium mycotoxins, which is best achieved by LC-MS/MS (liquid chromatography with tandem mass spectrometry). This review focuses on recent developments in the determination of mycotoxins with a special emphasis on LC-MS/MS and emerging rapid methods.

Quantification of zearalenone in various solid agroenvironmental samples using D6-zearalenone as the internal standard

Because of its pronounced estrogenicity, zearalenone may be of concern not only in the aqueous but also in the terrestrial environment. Therefore, we developed several analytical methods to quantify zearalenone in different solid matrices of agroenvironmental relevance (i.e., plant organs, soil, manure, and sewage sludge). The use of D(6)-zearalenone as the internal standard (IS) was essential to render the analytical method largely matrix-independent because it compensated for target analyte losses during extract treatment and ion suppression during ionization. Soil and sewage sludge samples were extracted with Soxhlet, whereas plant material and manure samples were extracted by liquid solvent extraction at room temperature. Absolute recoveries for zearalenone were 70-104% for plant materials, 105% for soil, 76% for manure, and 30% for sewage sludge. Relative recoveries ranged from 86 to 113% for all matrices, indicating that the IS was capable to largely compensate for losses during analysis. Ion suppression, between 8 and 74%, was in all cases compensated by the IS but influenced the method quantification levels. These were 3.2-26.2 ng/g(dryweightdw) for plant materials, 0.7 ng/g(dw) for soil, 12.3 ng/g(dw) for manure, and 6.8 ng/g(dw) for sewage sludge. Plant material concentrations varied from 86 ng/g(dw) to more than 16.7 microg/g(dw), depending on the organ and crop. Soil concentrations were between not detectable and 7.5 ng/g(dw), depending on the sampling depth. Zearalenone could be quantified in all manure samples in concentrations between 8 and 333 ng/g(dw). Except for two of the 85 investigated sewage sludge samples, zearalenone concentrations were below quantification limit.

Capillary electrophoresis of the mycotoxin zearalenone using cyclodextrin-enhanced fluorescence

Certain of the cyclodextrins are capable of significantly enhancing the native fluorescence of the estrogenic mycotoxin zearalenone (ZEN). Twenty-two cyclodextrins (CDs) were screened for their ability to enhance the fluorescence of ZEN in a capillary electrophoresis-laser induced fluorescence (CE-LIF) format. Of the CDs that were examined heptakis (2,6-di-O-methyl)-beta-CD gave the greatest enhancement. The heptakis (2,6-di-O-methyl)-beta-CD was applied to the development of a CE-LIF method for detection of ZEN in maize. The resulting method was capable of detecting ZEN with a limit of quantitation of 5 ng/g maize. Recoveries of ZEN from maize spiked over the range from 5 ng/g to 500 ng/g averaged 103.1+/-8.5% (n=20). The CE-LIF method will be useful for future studies of ZEN in maize.

Trace mycotoxin analysis in complex biological and food matrices by liquid chromatography–atmospheric pressure ionisation mass spectrometry

Mycotoxins are toxic secondary metabolites produced by filamentous fungi that are growing on agricultural commodities. Their frequent presence in food and their severe toxic, carcinogenic and estrogenic properties have been recognised as potential threat to human health. A reliable risk assessment of mycotoxin contamination for humans and animals relies basically on their unambiguous identification and accurate quantification in food and feedstuff. While most screening methods for mycotoxins are based on immunoassays, unambiguous analyte confirmation can be easily achieved with mass spectrometric methods, like gas chromatography/mass spectrometry (GC/MS) or liquid chromatography/mass spectrometry (LC/MS). Due to the introduction of atmospheric pressure ionisation (API) techniques in the late 80s, LC/MS has become a routine technique also in food analysis, overcoming the traditional drawbacks of GC/MS regarding volatility and thermal stability. During the last few years, this technical and instrumental progress had also an increasing impact on the expanding field of mycotoxin analysis. The aim of the present review is to give an overview on the application of LC-(API)MS in the analysis of frequently occurring and highly toxic mycotoxins, such as trichothecenes, ochratoxins, zearalenone, fumonisins, aflatoxins, enniatins, moniliformin and several other mycotoxins. This includes also the investigation of some of their metabolites and degradation products. Suitable sample pre-treatment procedures, their applicability for high sample through-put and their influence on matrix effects will be discussed. The review covers literature published until July 2006.

A rapid and sensitive LC-MS/MS method for determination of coenzyme Q10 in tobacco (Nicotiana tabacum L.) leaves

A rapid and sensitive liquid chromatography-tandem mass spectrometry method with multiple reaction monitoring has been proposed for the analysis of coenzyme Q10 in (CoQ10) tobacco leaves. The method used electrospray ionization with detection in positive ion mode. Sample pretreatment involved ultrasonic extraction of fresh tobacco leaves with anhydrous ethanol for 15 min and followed by extraction of the supernatant with hexane. The separation of CoQ10 was performed on a Symmetry Shield RP18 column with a mixture of acetonitrile and isopropanol (8:7, v/v) containing 0.5% formic acid as mobile phase. Quantification of CoQ10 was performed by the standard addition method. The limit of detection and limit of quantitation of CoQ10 were, respectively, 1.2 ng/mL (S/N = 3) and 4.0 ng/mL (S/N = 10). The relative standard deviations of peak area were 0.91% and 1.21% for intra-day and inter-day, respectively. The recoveries of CoQ10 ranged from 98.2 to 99.3% and the corresponding RSDs were less than 2.4%. Analysis took 5 min, making the method suitable for rapid determination of CoQ10 in tobacco leaves. The proposed method has been successfully applied to the analysis of CoQ10 in the leaves from eight varieties of tobacco.

Recent advances in mycotoxin determination in food and feed by hyphenated chromatographic techniques/mass spectrometry

Mycotoxins are fungal toxins produced by molds, which occur universally in food and feed derivatives, and are produced under certain environmental conditions in the field before harvest, post-harvest, during storage, processing, and feeding. Mycotoxin contamination is one of the most relevant and worrisome problem concerning food and feed safety because it can cause a variety of toxic acute and chronic effects in human and animals. In this review we report the use of mass spectrometry in connection with chromatographic techniques for mycotoxin determination by considering separately the most diffuse class of mycotoxins: patulin, aflatoxins, ochratoxin A, zearalenone, trichothecenes, and fumonisins. Although the selectivity of mass spectrometry is unchallenged if compared to common GC and LC detection methods, accuracy, precision, and sensitivity may be extremely variable concerning the different mycotoxins, matrices, and instruments. The sensitivity issue may be a real problem in the case of LC/MS, where the response can be very different for the different ionization techniques (ESI, APCI, APPI). Therefore, when other detection methods (such as fluorescence or UV absorbance) can be used for the quantitative determination, LC/MS appears to be only an outstanding confirmatory technique. In contrast, when the toxins are not volatile and do not bear suitable chromophores or fluorophores, LC/MS appears to be the unique method to perform quantitative and qualitative analyses without requiring any derivatization procedure. The problem of exact quantitative determination in GC/MS and LC/MS methods is particularly important for mycotoxin determination in food, given the high variability of the matrices, and can be solved only by the use of isotopically labeled internal standards or by the use of ionization interfaces able to lower matrix effects and ion suppressions. When the problems linked to inconstant ionization and matrix effects will be solved, only MS detectors will allow to simplify more and more the sample preparation procedures and to avoid clean-up procedures, making feasible low-cost, high-throughput determination of mycotoxins in many different food matrices.

Development and validation of a liquid chromatography/tandem mass spectrometric method for the determination of 39 mycotoxins in wheat and maize

This paper describes the first validated method for the determination of 39 mycotoxins in wheat and maize using a single extraction step followed by liquid chromatography with electrospray ionization triple quadrupole mass spectrometry (LC/ESI-MS/MS) without the need for any clean-up. The 39 analytes included A- and B-trichothecenes (including deoxynivalenol-3-glucoside), zearalenone and related derivatives, fumonisins, enniatins, ergot alkaloids, ochratoxins, aflatoxins and moniliformin. The large number and the chemical diversity of the analytes required the application of the positive as well as the negative ion ESI mode in two consecutive chromatographic runs of 21 min each. The solvent mixture acetonitrile/water/acetic acid 79 + 20 + 1 (v/v/v) has been determined as the best compromise for the extraction of the analytes from wheat and maize. Raw extracts were diluted 1 + 1 and were injected without any clean-up. Ion-suppression effects due to co-eluting matrix components were negligible in the case of wheat, whereas significant signal suppression for 12 analytes was observed in maize, causing purely proportional systematic errors. Method performance characteristics were determined after spiking blank samples on multiple levels in triplicate. Coefficients of variation of the overall process of <5.1% and <3.0% were obtained for wheat and maize, respectively, from linear calibration data. Limits of detection ranged from 0.03 to 220 microg/kg. Apparent recoveries (including both the recoveries of the extraction step and matrix effects) were within the range of 100 +/- 10% for approximately half of the analytes. In extreme cases the apparent recoveries dropped to about 20%, but this could be compensated for to a large extent by the application of matrix-matched standards to correct for matrix-induced signal suppression, as only a few analytes such as nivalenol and the fumonisins exhibited incomplete extraction. For deoxynivalenol and zearalenone, the trueness of the method was confirmed through the analysis of certified reference materials.

Development of a multicomponent method forFusariumtoxins using LC-MS/MS and its application during a survey for the content of T-2 toxin and deoxynivalenol in various feed and food samples

A reliable, sensitive and selective method was developed to determine different Fusarium mycotoxins (trichothecenes Type A and B, zearalenone) simultaneously in cereals and cereal-based samples using liquid chromatography with tandem mass spectrometry (LC-ESI-MS/MS). Sample preparation is based on a standard solvent extraction step followed by two different kinds of solid-phase clean-up procedures: using a multifunctional MycoSep material for trichothecenes and zearalenone. The average recoveries for trichothecenes ranged from 65% for nivalenol (NIV) up to 96% for deoxynivalenol (DON) and 89% for zearalenone (ZON). The limit of quantification varied between 0.02 and 10 ppb for each substance. In addition, a screening survey with 685 samples was carried out to compare contents of T-2 toxin and deoxynivalenol and to investigate potential coherence in contamination pattern.

Rapid simultaneous determination of major type A- and B-trichothecenes as well as zearalenone in maize by high performance liquid chromatography-tandem mass spectrometry

A novel method for the simultaneous determination of the Fusarium mycotoxins nivalenol, deoxynivalenol, fusarenon-X, 3-acetyl-deoxynivalenol, the sum of 3-acetyl-deoxynivalenol and 15-acetyl-deoxynivalenol, diacetoxy-scirpenol, HT-2 toxin, T-2 toxin and zearalenone in maize has been developed using gradient RP-LC with atmospheric pressure chemical ionization triple quadrupole mass spectrometry (LC-APCI-MS/MS). Swift clean-up of maize samples was performed with MycoSep #226 columns. Quantification of zearalenone was performed with zearalanone as internal standard (IS), while no IS was used for the trichothecenes. Detection of the mycotoxins was carried out in the multiple reaction monitoring (MRM) mode. Method performance characteristics were estimated after analysis of spiked blank maize samples. Calibration curves were linear between 10 and 1000 microg/kg and the limits of detection ranged from 0.3 to 3.8 microg/kg depending on the mycotoxin. Moreover, the accuracy of the method was confirmed by comparing analytical data to certified values from reference materials for deoxynivalenol and zearalenone.

Determination of zearalenone from wheat and corn by pressurized liquid extraction and liquid chromatography-electrospray mass spectrometry

Zearalenone (ZON) was extracted from wheat and corn by using pressurized liquid extraction (PLE) and the PLE extracts were analyzed using liquid-chromatography-mass spectrometry (LC-MS) without further clean-up procedures. A statistical design approach was applied to evaluate the influence of several extraction parameters such as temperature (40 degrees C; 80 degrees C; 120 degrees C), time (5 min; 10 min) and solvent extraction mixture [acetonitrile-water (9:1, v/v); methanol-water (8:2, v/v); methanol-acetonitrile (1:1, v/v)] on fortified cereals. The results showed a strong influence of the solvent composition on recovery of ZON. Quantification of the analytes was performed by LC-MS analysis of the raw extract using matrix-matched standard curves. The method performance was tested in the selected conditions (80 degrees C; 5 min; two cycles; methanol-acetonitrile) on samples which had been previously used for an international proficiency test. Compared to the assigned value, the recovered ZON was 118% [relative standard deviation (RSD)=5.2%, n=3)] and 107% (RSD=2.2%, n=3) in wheat and corn, respectively. Therefore, PLE can be used for ZON extraction, achieving good performances and allowing for an automated handling of the sample extraction step. Successively, the influence of temperature and number of cycles was investigated on naturally contaminated corn. From these results it could be concluded that fortified experiments perfectly mimicked naturally contaminated samples.

Simultaneous quantification of A-trichothecene mycotoxins in grains using liquid chromatography-atmospheric pressure chemical ionisation mass spectrometry

An approach for simultaneous determination of the main type A-trichothecenes by liquid chromatography and atmospheric pressure chemical ionization mass spectrometry is described. Parameters for coupling of LC-MS such as cone voltage, nebulizing temperature and the LC flow-rate, were optimized to provide detection of mycotoxins with maximum sensitivity. Furthermore, the effects of cone voltage and temperature on the fragmentation pattern of the tested toxins were studied. Main type A-trichothecenes such as T-2 Toxin, HT-2 Toxin, acetyl T-2 Toxin, diacetoxyscirpenol, monoacetoxyscirpenol (15-acetoxyscirpenol) and neosolaniol were separated on a reversed-phase narrow bore C18 column, using a linear gradient and a flow-rate of 0.3 ml/min. Mass spectra were obtained in positive ion mode for confirmation and quantitation. The method involves extraction and purification of toxins by using multifunctional Mycosep columns. Deuterated T-2 Toxin was used as an internal standard. A linear working range between 80 and 500 microg/kg in matrix with an acceptable correlation coefficient was observed. The developed method was validated by using a blank oats sample. The detection limit in the matrix was found to be between 50 and 85 microg/kg in selected ion mode for all tested A-trichothecenes. Recovery data were found to be between 77 and 101%. Within run and day-to-day precision were determined as having comparable levels to those found using GC methods. Furthermore, the matrix effect was investigated by comparing the internal standard versus the external standard method in quantification studies. In addition, the developed method was applied for the analysis of naturally contaminated oats, maize, barley and wheat samples.

Liquid chromatographic determination of toxigenic secondary metabolites produced by Fusarium strains

Various liquid chromatographic methods used in the analysis of mycotoxins (zearalenone, trichothecenes and fumonisins) produced by Fusarium species were compared in this work. The results demonstrate the suitability of modern clean-up procedures employing multifunctional MycoSep and immunoaffinity columns although these methods are more expensive than conventional methodologies for clean-up. HPLC with both fluorescence and photodiode array detection is a suitable technique for the analysis of toxic secondary metabolites produced by Fusarium species; different derivatisation strategies have been studied to improve the sensitivity of the technique because of the low concentration of these metabolites in contaminated food. The utility of the proposed methodology was assessed in cereal cultures of various Fusarium strains.

Concentration levels of zearalenone and its metabolites in urine, muscle tissue, and liver samples of pigs fed with mycotoxin-contaminated oats

The content of zearalenone and its metabolites in urine and tissue samples from pigs fed zearalenone-contaminated oats was established by analytical methods combining solid-phase extraction cleanup of the samples with highly selective liquid chromatography-mass spectrometry (LC-MS)/MS detection. Investigation of the urine samples revealed that approximately 60% of zearalenone was transformed in vivo to alpha-zearalenol and its epimer beta-zearalenol in a mean ratio of 3:1. Zeranol and taleranol as further metabolites could only be detected in trace amounts. Zearalanone was identified at considerable concentrations, though only in a couple of samples. In contrast, liver samples contained predominantly alpha-zearalenol, and to a minor extent beta-zearalenol and zearalenone, with a mean ratio of alpha-/beta-zearalenol of 2.5:1, while zeranol, taleranol, or zearalanone could not be identified in any of the investigated samples. The degree of glucoronidation was established for zearalenone as 27% in urine and 62% in liver; for alpha-zearalenol as 88% in urine and 77% in liver; and for beta-zearalenol as 94% in urine and 29% in liver. Analyses of muscle tissue revealed relatively high amounts of nonglucuronidated zeranol and alpha-zearalenol together with traces of taleranol and zearalenone, indicating that the metabolism of zearalenone and its metabolites is not restricted to hepatic and gastrointestinal metabolic pathways.

Characterization of tetanus toxin, neat and in culture supernatant, by electrospray mass spectrometry

A method was developed for the liquid chromatographic-mass spectrometric (LC-MS) identification of extremely neurotoxic toxins. The method combines sample treatment in a safety containment and analysis of detoxified material in a common laboratory facility. The method was applied to the characterization of neat tetanus toxin and subsequent identification of the toxin in cell lysate supernatants and culture supernatants from different Clostridium tetani bacteria strains. Characterization of the neat toxin was accomplished by (1) accurate mass measurement of enzyme digest fragments of the toxin and (2) tandem mass spectrometric (MS/MS) amino acid sequencing of selected peptides. Accurate mass measurement proved no longer feasible for the analysis of supernatants, due to the overwhelming presence of peptides from proteins other than toxin. Even when high-molecular-weight proteins were filtered from the lysates and treated, the retained protein fraction yielded too many peptides. However, MS/MS could successfully be applied when the findings from the characterization of neat toxin were employed. Thus, LC-MS/MS of selected precursor ions from trypsin digest fragments yielded specific sequence data for identification of the toxin. This procedure provided reliable identification of the toxin at levels above 1 microg/ml and within a day. Investigations with the method developed will be extended to the botulinum neurotoxins.

Ion trap MS(n) for identification of gliotoxin as the cytotoxic factor of a marine strain of Aspergillus fumigatus Fresenius

When cultured in a marine solid medium, a strain of Aspergillus fumigatus (Fresenius) isolated from a shellfish-farming area in the Loire estuary (France) produced a highly cytotoxic exudate. To identify the origin of this activity, a cytotoxicity test on KB cells was used to monitor the purification of the exudate, together with electrospray/ion trap/mass spectrometry (ESI/IT/MS(n)) to detect and identify the toxic compound. After three purification stages, a comparison of fullscan analyses of the last six fractions showed that a monocharged compound at m/z 349 was present only in the active fraction, corresponding to the sodium adduct of gliotoxin [C(13)H(14)N(2)O(4)S(2)+Na](+). Isotopic distribution determination showed that the m/z 349 product possessed two sulphur atoms and multi-stage fragmentation confirmed the hypothesis. MS/MS analysis exhibited the characteristic gliotoxin loss of the disulphide intracyclic bridge. MS(3) analysis revealed four main ions and confirmed the identity of the m/z 349 ion. This study points out that the combined use of a KB cells bioassay and ESI/IT/MS(n) allows a fast and very specific detection and elucidation of unidentified cytotoxic products in natural samples. This method does not require total purification, and it allowed us to report the first detection of gliotoxin production in marine conditions.

Application of manual and automated systems for purification of ochratoxin a and zearalenone in cereals with immunoaffinity columns

A manual vacuum manifold and an automated solid phase extraction (ASPEC) system were applied for purification of ochratoxin A and zearalenone in wheat, rye, barley, and oat samples with immunoaffinity columns followed by separation with a high-performance liquid chromatograph and fluorescence detection. The immunoaffinity columns for manual sample purification were purchased from a different manufacturer than were those for the automated system. The limit of detection (LOD) for the method for ochratoxin A with a vacuum manifold and ASPEC was 0.1 microg/kg. For the method for zearalenone, the LODs were 1.5 microg/kg with a vacuum manifold and 3 microg/kg with ASPEC. For the methods for ochratoxin A at spiking levels of 0.6 and 2.5 microg/kg, mean recoveries for different cereals varied from 68 to 106%. For the methods for zearalenone, mean recoveries varied from 78 to 117% at spiking levels of 9 and 25 microg/kg. The relative standard deviations of repeatability with various cereals employing both methods were 2-15 and 2-19% for ochratoxin A and zearalenone, respectively.

Development of an analytical system for the simultaneous determination of anabolic macrocyclic lactones in aquatic environmental samples

An analytical procedure that enables routine analysis for trace determination of six anabolic macrocyclic lactones (zearalenone, alpha- and beta-zearalenol, zearalanone, zeranol, and taleranol) in sewage treatment plant (STP) samples has been developed. The method uses solid-phase extraction, followed by high-performance liquid chromatography with on-line tandem mass spectrometry using atmospheric pressure chemical ionization (LC/APCI-MS/MS). The extraction of these compounds from filtered water samples was performed off-line with C(18) solid-phase cartridges. The detection was achieved by isocratic reversed-phase high-performance liquid chromatography coupled with an heated nebulizer (HN) APCI interface operating in negative ion mode. Mean recovery of the analytes in STP effluent samples generally exceeded 81%. This method was used to determine the occurrence of target analytes in the aquatic environment. In the selected STP effluent samples, zearalenone and alpha-zearalenol were detected in the ng/L range.

Determination of zearalenone and its metabolites alpha- and beta-zearalenol in beer samples by high-performance liquid chromatography-tandem mass spectrometry

A fast, robust and sensitive LC-MS-MS method for the determination of zearalenone (ZON) and its metabolites alpha-zearalenol (alpha-ZOL) and beta-zearalenol (beta-ZOL) in beer samples is described. Sample preparation was performed by direct RP-18 solid-phase extraction of undiluted beer samples followed by selective determination of analytes by LC-MS-MS applying an atmospheric pressure chemical ionization (APCI) interface. Using the negative ion mode limits of determination of 0.03-0.06 microg l(-1) beer and limits of quantification of 0.07-0.15 microg l(-1) beer were achieved, which was distinctly more sensitive than in the positive ion mode. Twenty-three beer samples from different countries, produced from different grains and under different brewing conditions, were investigated by this method, but only in one sample could beta-ZOL and ZON be detected. Independently of the type of beer, relative standard deviations between 2.1% and 3.3%, a linear working range of 0.15 microg l(-1) to 500 microg l(-1) beer and recovery rates around 100% could be achieved when zearalanone (ZAN) was used as internal standard.