Optimisation of a sample preparation method for the determination of fumonisin B1 in rice

A simple, rapid and cost-effective sample preparation method for the determination of fumonisin B1 in rice was optimised using a strategy of sequential experimental designs. Initially, a Plackett-Burman design was applied to select the statistically significant variables for the determination of fumonisin B1, and then, a central composite rotatable design was used to define the optimal conditions of these variables. The method involves extraction with a 50% acetonitrile aqueous solution and glacial acetic acid, liquid-liquid partitioning with addition of anhydrous sodium sulphate and sodium chloride, followed by dispersive SPE clean-up with diatomaceous earth. The final extract was analysed by HPLC-FLD after precolumn derivatisation with ortho-phthaldialdehyde. The optimised method was validated for selectivity, linearity, matrix effect, limits of detection and quantification, trueness, and precision, and then applied to commercial samples of polished rice. This is the first report of the occurrence of fumonisin B1 in commercial samples of polished rice from the Southeast region of Brazil.