Stable isotope dilution assay for the accurate determination of mycotoxins in maize by UHPLC-MS/MS

A fast, easy-to-handle and cost-effective analytical method for 11 mycotoxins currently regulated in maize and other cereal-based food products in Europe was developed and validated for maize. The method is based on two extraction steps using different acidified acetonitrile–water mixtures. Separation is achieved using ultrahigh-performance liquid chromatography (UHPLC) by a linear water–methanol gradient. After electrospray ionisation, tandem mass spectrometric detection is performed in dynamic multiple reaction monitoring mode. Since accurate mass spectrometric quantification is hampered by matrix effects, uniformly [13C]-labelled mycotoxins for each of the 11 compounds were added to the sample extracts prior to UHPLC-MS/MS analysis. Method performance parameters were obtained by spiking blank maize samples with mycotoxins before as well as after extraction on six levels in triplicates. The twofold extraction led to total recoveries of the extraction steps between 97% and 111% for all target analytes, including fumonisins. The [13C]-labelled internal standards efficiently compensated all matrix effects in electrospray ionisation, leading to apparent recoveries between 88% and 105% with reasonable additional costs. The relative standard deviations of the whole method were between 4% and 11% for all analytes. The trueness of the method was verified by the measurement of several maize test materials with well-characterized concentrations. In conclusion, the developed method is capable of determining all regulated mycotoxins in maize and presuming similar matrix effects and extraction recovery also in other cereal-based foods

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

Different sample treatment approaches for the analysis of T-2 and HT-2 toxins from oats-based media

A LC-DAD method is proposed for the determination of the T-2 and HT-2 toxins in cultures of Fusarium langsethiae in oat-based and other in vitro media. Test media consisted of freshly prepared milled oats to which T-2 and HT-2 toxin stock solutions were added. Different mixtures of extraction solvent (acetonitrile:water and methanol water), extraction times (30', 60' or 90') and drying methods were investigated. Results showed that extraction with methanol: water (80:20, v/v) for 90 min, drying with N-2 and subsequent analysis by LC-DAD was the fastest and most user friendly method for detecting HT-2 and T-2 toxins production by F. langsethiae strains grown on oat-based media at levels of 0.459 and 0.508 mg of toxin/kg of agar, respectively. The proposed method was used to investigate toxin production of 6 F. langsethiae strains from northern Europe and provided clear chromatograms with no interfering peaks in media with and without glycerol as water activity modifier. (C) 2010 Elsevier B.V. All rights reserved

Short-term effects of T-2 toxin exposure on some lipid peroxide and glutathione redox parameters of broiler chickens

The purpose of this study was to investigate the short-term effects of T-2 toxin exposure (3.09 mg/kg feed) on lipid peroxidation and glutathione redox system of broiler chicken. A total of 54 Cobb 500 cockerels were randomly distributed to two experimental groups at 21 days of age. Samples (blood plasma, red blood cell, liver, kidney and spleen) were collected every 12 h during a 48-h period. The results showed that the initial phase of lipid peroxidation, as measured by conjugated dienes and trienes in the liver, was continuously, but not significantly higher in T-2 toxin-dosed birds than in control birds. The termination phase of lipid peroxidation, as measured by malondialdehyde, was significantly higher in liver and kidney as a result of T-2 toxin exposure at the end of the experimental period (48th hour). The glutathione redox system activated shortly after starting the T-2 toxin exposure, which is supported by the significantly higher concentration of reduced glutathione and glutathione peroxidase activity in blood plasma at 24 and 48 h, in liver at 12, 24 and 36 h, and in kidney and spleen at 24 h. These results suggest that T-2 toxin, or its metabolites, may be involved in the generation of reactive oxygen substances which causes an increase in lipid peroxidation, and consequently activates the glutathione redox system, namely synthesis of reduced glutathione and glutathione peroxidase