Determination of fumonisin B1 by HPLC: stability study of the fumonisin B1-ortho-phthaldialdehyde derivative

Abstract

The present study aimed at evaluating the stability of fumonisin B1-ortho-phthaldialdehyde derivative under different conditions of pH, time and temperature, during the derivatization reaction and chromatographic analysis. In the derivatization, the maximum fluorescence emitted by the derivative product was obtained employing a 0.1 M sodium tetraborate solution at pH 9.0, and this did not differ significantly from those emitted at pH 8.0, 8.5, 9.5 and 10.0. Within 2 minutes of reaction, the maximum fluorescence was observed and no significant difference was found when compared with those emitted at 4, 6 and 8 minutes of reaction. The 0.5 unit variation in the pH of 0.1 M sodium phosphate buffer solution, which was used as mobile phase, caused a significant effect on the chromatographic separation and on the fumonisin B1-ortho-phthaldialdehyde derivative detection. The highest fluorescence intensities were found at pH from 3.3 to 3.8. Reduction in the fluorescence intensity was causes by increasing the chromatographic column temperature. The fumonisin B1-ortho-phthaldialdehyde derivative remained stable from 20 ºC to 27 ºC. At 30 °C, it was found a significant reduction in 26.5% in the fluorescence intensity emitted by the derivative product.