Chromatographic methods as tools in the field of mycotoxins

Analytical methods for determination of mycotoxins: a review

Mycotoxins are small (MW approximately 700), toxic chemical products formed as secondary metabolites by a few fungal species that readily colonise crops and contaminate them with toxins in the field or after harvest. Ochratoxins and Aflatoxins are mycotoxins of major significance and hence there has been significant research on broad range of analytical and detection techniques that could be useful and practical. Due to the variety of structures of these toxins, it is impossible to use one standard technique for analysis and/or detection. Practical requirements for high-sensitivity analysis and the need for a specialist laboratory setting create challenges for routine analysis. Several existing analytical techniques, which offer flexible and broad-based methods of analysis and in some cases detection, have been discussed in this manuscript. There are a number of methods used, of which many are lab-based, but to our knowledge there seems to be no single technique that stands out above the rest, although analytical liquid chromatography, commonly linked with mass spectroscopy is likely to be popular. This review manuscript discusses (a) sample pre-treatment methods such as liquid-liquid extraction (LLE), supercritical fluid extraction (SFE), solid phase extraction (SPE), (b) separation methods such as (TLC), high performance liquid chromatography (HPLC), gas chromatography (GC), and capillary electrophoresis (CE) and (c) others such as ELISA. Further currents trends, advantages and disadvantages and future prospects of these methods have been discussed.

Simple and sensitive determination of citrinin in Monascus by GC-selected ion monitoring mass spectrometry

A new method for the qualitative and quantitative analysis of citrinin in Monascus by gas-chromatography-selected ion monitoring (SIM) mass spectrometry has been developed. GC separation of citrinin in Monascus extract was achieved without the need for chemical derivatization, and could be detected as a single peak when the SIM mode selected 5 prominent fragmentations (m/z of 220, 205, 177, 105 and 91). The quantitative detection limit for citrinin was approximately 1 ppb. Finally, the GC-separated analyte from Monascus extract, at a retention time of 10.89 min, was examined by the method of pattern recognition by comparison with a citrinin standard. The results show that the 2 compounds had a 94% similarity when the SIM mode was used.

Application of the assay of aflatoxins by liquid chromatography with fluorescence detection in food analysis

HPLC using fluorescence detection has already become the most accepted method for the determination of aflatoxins due to its several advantages over other analytical methods. Both normal- and reversed-phase HPLC can be used. However the reversed-phase HPLC methods are more popular. Liquid chromatographic determination of aflatoxins using fluorescence detection and its application in food analysis is reviewed in this article.

High-performance liquid chromatography-atmospheric-pressure chemical ionization mass spectrometry as a new tool for the determination of the mycotoxin zearalenone in food and feed

A new method for the determination of the mycotoxin zearalenone (ZON) in food and feed, based on HPLC-MS with an atmospheric-pressure chemical ionization (APCI) interface after extraction from cereals and clean-up by either conventional solid-phase or immunoaffinity cartridge is presented. The APCI interface parameters are optimized to provide detection of ZON with maximum sensitivity after RP separation of ZON on a C18 column with acetonitrile-water (40:60, v/v) at 1 ml/min column flow without split. Using APCI-MS detection, the sensitivity of the method was improved by a factor of ca. 50 in comparison to HPLC with fluorescence detection, allowing determination of ZON down to 0.12 microgram/kg maize which is well below present threshold values. Due to the selectivity of MS detection, it also was possible to quantitatively determine ZON both in raw extracts without clean-up using a normal-size (100 mm) chromatographic column or using only a short (20 mm) chromatographic column, when a clean-up was done to minimize possible interferences.

Derivatization reactions for the determination of aflatoxins by liquid chromatography with fluorescence detection

Various derivatization methods for the fluorometric detection of aflatoxins after separation by HPLC are reviewed. In normal-phase chromatography the sensitivity for aflatoxins B1 and B2 was improved by using special mobile phases or a flow cell packed with silica-gel particles. In the nowadays more popular reversed-phase methods, the fluorescence intensity of B1 and G1 can be increased by precolumn derivatization with trifluoroacetic acid or by postcolumn derivatization with iodine or bromine. Optimum conditions for the reactions are discussed. In terms of sensitivity, the three derivatization schemes give similar results. The methods are compared with respect to experimental convenience, selectivity, reproducibility and suitability for automation.

Levels of five mycotoxins in grains harvested in Atlantic Canada as measured by high performance liquid chromatography

An analytical protocol using high performance liquid chromatography (HPLC) was used to analyze samples of spring wheat, winter wheat, 2-row barley, and 6-row barley over a period of three years for the presence of five mycotoxins. These included deoxynivalenol, zearalenone, T-2 toxin, HT-2 toxin, and diacetoxyscirpenol. The protocol employed a single extraction step using acetonitrile-water and two cleanup procedures. One utilized a solid-phase extraction column and the other a charcoal-alumina column. Detection limits ranged from 0.02 to 0.15 micrograms of mycotoxin g-1 grain. Little T-2 toxin, HT-2 toxin, or diacetoxyscirpenol was found in the samples. Deoxynivalenol was detected in 53 to 62% of the samples tested and zearalenone in 25-29% of the samples. Several enzyme-linked immunosorbent assays were used for comparison purposes with deoxynivalenol, zearalenone, and T-2 toxin. These kits provided reliable qualitative, but not quantitative, data.

Determination of aflatoxins in food products by chromatography

Several chromatographic methods for the determination of aflatoxins in agricultural and food products are reviewed. During the past two decades, identification and determination of aflatoxins were done by thin-layer chromatography (TLC) because it was easy, fast and inexpensive. However, high-performance liquid chromatography (HPLC) using fluorescence detection is now the method of choice for determining aflatoxins and is also growing in popularity for their identification. The reasons for selecting HPLC over TLC can be summarized as the ability to analyze for a wide variety of compounds, including compounds that are easily degraded by heat, light or air, the ease of adaptation to confirmatory procedures, the potential for automation and the dramatic improvement in instrumentation, including the development of increasingly sensitive fluorescence and electrochemical detectors and short, high-resolution, reversed-phase columns.