Development and validation of a liquid chromatography/tandem mass spectrometric method for the determination of 39 mycotoxins in wheat and maize. Rapid Commun Mass Spectrom 20: 2649
Christian-Doppler-Research Laboratory "CEREVAL", University of Natural Resources and Life Science Vienna, Wien, Vienna, Austria Rapid Communications in Mass Spectrometry
(Impact Factor: 2.25).
09/2006; 20(18):2649-59. DOI: 10.1002/rcm.2640
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.
Available from: Malgorzata Okrasa
- "Next, 0.5 g of dust samples were suspended in 5 mL of the extraction solvent (acetonitrile/water/acetic acid 79:20:1, v:v:v). Samples were extracted for 90 min and diluted with the same volume of solvent prior to injection  Secondary metabolite concentrations were analysed quantified using LC-MS/MS, as described by Sulyok et al.  with further modification. Parameters for liquid chromatography and mass spectrometry are described elsewhere . "
- "In raw maize, hidden rather than bound FBs occur (Dall'Asta et al. 2009), while bound FBs can be mainly formed during thermal processes. As regards hidden FBs, the associative interactions with matrix macro-constituents could be broken during the extraction process, depending on different conditions applied during extraction (solvent polarity, pH, ionic strength, time, and temperature; Kim et al. 2002; Sulyok et al. 2006). For this reason, the contamination levels of free FBs can be different when different extraction mixtures are used (Pietri and Bertuzzi 2012). "
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ABSTRACT: Fumonisins B (FBs) can occur in maize as free forms and as hidden FBs (interaction between FBs and matrix macro-constituents). The analytical methods to detect free FBs in maize and derived products usually involve extraction with aqueous methanol and/or acetonitrile; for hidden FBs, alkaline hydrolysis (2 M KOH) and following CH3CN extraction is used. Recently, we proposed a simple phosphate buffer (PB) extraction to detect free FBs in masa and maize samples. This study aimed at evaluating if this method is suitable to detect also hidden FBs; then, a comparison between the most common solvents, PB, and alkaline hydrolysis was carried out. For maize samples, the results showed that 0.4 M PB can extract both free and most hidden FBs; however, this method was not suitable for some categories of maize-based processed food products, in particular cornflakes, chips, and crispbreads. To solve this drawback, a modified PB extraction, which entails the addition of Carrez solutions in order to precipitate proteins, was tested and satisfactory results were obtained. Finally, the alkaline hydrolysis of maize-based food extracts showed that bound FBs can be co-extracted together with free forms by 0.4 M PB and quantified as hydrolyzed FBs.
Available from: Gordon S Shephard
- "It is well known that food and feed can be contaminated by several different mycotoxins. Liquid Chromatography coupled to Mass Spectrometry (LC-MS/MS) methods are now widely used analytical techniques for the simultaneous detection and quantification of multiple mycotoxin contamination (Sulyok et al. 2006; Spanjer et al. 2008; Streit et al. 2013). LC-MS/MS allows for sensitive and specific multi-mycotoxin analysis without time consuming sample preparation i.e. extraction, clean-up, pH modification and pre-concentration of analytes (Sulyok et al. 2010; Mol et al. 2008). "
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ABSTRACT: The aim of this study was to assess mycotoxin contamination of crops grown by rural subsistence farmers over two seasons (2011 and 2012) in two districts, Vhembe District Municipality (VDM, Limpopo Province) and Gert Sibande District Municiality (GSDM, Mpumalanga Province) in northern South Africa and to evaluate its impact on farmers' productivity and human and animal health. A total of 114 maize samples were collected from 39 households over the two seasons and were analysed using a validated LC-MS/MS mycotoxins method. Aflatoxin B1 (AFB1) occurrence ranged from 1 to 133 µg kg(-1) in VDM while AFB1 levels in GSDM were less than 1.0 µg kg(-1) in all maize samples. Fumonisin B1 (FB1) levels ranged from 12 to 8514 µg kg(-1) (VDM) and 11-18924 µg kg(-1) (GSDM) in 92% and 47% positive samples respectively, over both seasons. Natural occurrence and contamination with both fumonisins and aflatoxins in stored home-grown maize from VDM was significantly (p < 0.0001) higher than from GSDM over both seasons.
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