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Abstract
The recent discovery that Aspergillus niger can produce fumonisins raises a new mycotoxigenic risk that requires additional studies to assess the impact on agricultural commodities. Here, we report the development and validation of a sensitive LC-fluorescence method for the identification of fumonisin B2 in black aspergilli cultures. The performances of naphthalene-2,3-dicarboxaldehyde (NDA), o-phthaldialdehyde (OPA), and 9-fluorenylmethyl chloroformate (FMOC) for the precolumn derivatization of samples were evaluated and compared. The best methodology included the following elements: NDA was used during pre-column derivatization; the derivatives were separated by a 30 min isocratic elution with acetonitrile/H2O/acetic acid (60:40:1, v/v/v), pumped at a flow rate of 1 mL · min−1 on a polar C18 reversed-phase YMC-Pack ODS-AQ column (250 × 4.6 mm, 5 µm); and fluorescence detection using excitation and emission wavelengths of 420 and 500 nm, respectively. The calibration curve was found to give a good linear response (r2 > 0.9999) from 1 to 200 µg · L−1. For FB2, which is the main fumonisin detected in black aspergilli thus far, this method measured an LOD and an LOQ of 2 and 6 µg · kg−1, respectively. Using this method, the amount of FB2 in black aspergilli cultures can be simply and rapidly determined.
ACKNOWLEDGMENTS
Luís Abrunhosa was supported by the grant SFRH/BPD/43922/2008 from Fundação para a Ciência e Tecnologia – FCT, Portugal. Tiago Resende was supported by CEB under the FCT BII program.
Notes
tr = retention time (min); y = peak area of FB2 in µvolts.min−1 (n = 10); x = concentration in µg · L−1; a = slope; b = intercept; Sa and Sb = standard deviations of slope and intercept, respectively; LOD = limit of detection; LOQ = limit of quantification.
nd = not detected.