Analysis of trichothecene mycotoxins in human blood by capillary column gas chromatography-ammonia chemical ionization mass spectrometry

The pivotal role of mass spectrometry in determining the presence of chemical contaminants in food raw materials

During recent years, a rising interest from consumers and various governmental organizations towards the quality of food has continuously been observed. Human intervention across the different stages of the food supply chain can lead to the presence of several types of chemical contaminants in food-based products. On a normal daily consumption basis, some of these chemicals are not harmful; however, for those that present a risk to consumers, legislation rules were established to specify tolerance levels or in some cases the total forbiddance of these specific contaminants. Hence, the use of appropriate analytical tools is recommended to properly identify chemical contaminants. In that context, mass spectrometry (MS)-based techniques coupled or not to chromatography offer a vast panel of features such as sensitivity, selectivity, quantification at trace levels, and/or structural elucidation. Because of the complexity of food-based matrices, sample preparation is a crucial step before final detection. In the present manuscript, we review the contribution and the potentialities of MS-based techniques to ensure the absence of chemical contaminants in food-based products.

Indirect electrochemical detection of type-B trichothecene mycotoxins

Trichothecene mycotoxins in animal feed and human food can cause fatalities in livestock and disease in humans. In addition, these toxins are suspected chemical warfare agents. Therefore, development of a simple and sensitive method for the screening of trichothecenes is important to prevent economic loss and health hazards. A simple and inexpensive method for the detection of type-B trichothecene mycotoxins has been developed in our laboratory. By hydrolyzing the toxin under basic conditions at 80 degrees C for 1 h it is possible to detect the toxin with simple electrochemical techniques. Deoxynivalenol (DON), commonly known as vomitoxin, was used as a representative compound for type-B trichothecenes in this detection scheme. The detection limit for DON using our procedures was determined to be 9.1 microM in solution, corresponding to 0.24 ppm in a 25-g grain sample if the final extraction volume is 2.2 mL. The linear dynamic detection range was determined to be from 0.32 ppm to greater than 32 ppm. In addition to standard solutions, this method was used on rice samples spiked with DON. It was demonstrated that there is no electrochemical interference from rice extract and that 1 ppm of DON in rice samples can be quantified. This method may be ideal for toxin screening in animal feeds or in runoff from sites that produce the compounds as chemical warfare agents. Since the active moiety in DON is common to virtually all type-B trichothecenes, our approach may be ideal for type-specific screening.

Identification of mycotoxins in keratomycosis-derived Fusarium isolates by gas chromatography-mass spectrometry

The production of mycotoxins from Fusarium species has been demonstrated in isolates cultured from patients suffering from keratomycosis. The method employed a combination of thin-layer chromatography directly performed on gel plugs taken from the growth medium, cartridge column chromatography, silylation and gas chromatography on a non-polar stationary phase capillary column linked to mass spectrometry. The sensitivities of detection obtained for a signal-to-noise ratio of 33:1, were 200 pg for single stage GC-MS and 20 pg using tandem GC-MS-MS. Two mycotoxins, diacetoxyscirpenol and T-2 toxin were identified in three cultures.

Chromatographic methods as tools in the field of mycotoxins

Achievements in the applications of chromatographic techniques in mycotoxicology are reviewed. Historically, column chromatography (CC) and paper chromatography (PC) were applied first, followed by thin-layer chromatography (TLC), high-performance liquid chromatography (HPLC) and gas chromatography (GC). Although PC techniques are no longer used in the analysis of mycotoxins, selected applications of PC are included to underline historical continuity. The most important achievements published from 1980 onwards are described. They include clean-up methods, TLC, CC, HPLC and GC of mycotoxins in environmental samples, foods, feeds, body fluids and in studies on biosynthesis and biotransformations of mycotoxins. Advantages and disadvantages of chromatographic techniques used in mycotoxicology are also evaluated.

Characterization of trichothecenes by tandem mass spectrometry using reactive collisions with ammonia

The use of low-energy (7 eV Elab) reactive collisions with ammonia provides a highly specific method for the characterization of trichothecenes since the collisions between the protonated molecule and ammonia not only produce ions formed by collisionally activated dissociation but ammonium adduct ions and ions formed by substitution reactions. The good detection limits (20-300 pg) and good quantitative reproducibility (relative standard deviations are 5-10%) mean that the use of reactive collisions with ammonia is also very suitable for monitoring and quantitative analyses.

Characterization of trichothecenes by ammonia chemical ionization and tandem mass spectrometry

Ammonia and deuterated ammonia chemical ionization (CI) mass spectra and collisionally activated dissociation (CAD) mass spectra of ammonium adduct ions are presented for ten trichothecenes. The samples were introduced by direct exposure probe. Effects of ion source temperature and pressure on the ammonia CI gas plasma and the formation of the ammonium adduct ion were studied. The CI conditions were optimized to produce a maximal yield for the ammonium adduct ion of trichothecenes, i.e. the parent ion for tandem mass spectral analysis. Besides source temperature and pressure, proton affinity and the stability of the ammonium adduct ion affect the relative abundance ratio of [M + H]+:[M + NH4]+ in ammonia CI and CAD mass spectra. The ratio [M + H]+:[M + NH4]+, and hence the stability of the ammonium adduct ion, are largely determined by the functional groups (hydroxy, carbonyl, acetoxy, and isovaleroyloxy) and their location in the trichothecene nucleus. The most abundant fragment ions in the ammonia CI spectra and the most abundant daughter ions in the CAD spectra of the ammonium adduct ions are formed by the losses of ammonia and functional groups as neutrals in various combinations.