Enhanced spectrofluorimetric determination of aflatoxin B1 in wheat by second-order standard addition method

Determination of aflatoxin B1 (AFB1) in wheat has been accomplished by enhanced spectrofluorimetry in combination with second-order standard addition method (EF-SOSAM). The adopted strategy combined the use of parallel factor analysis (PARAFAC) for extraction of the pure analyte signal and the standard addition method, for a determination in the presence of matrix effect caused by wheat matrix. The method is based on the enhanced fluorescence of AFB1 by β-cyclodextrin in 10% (w/w) methanol–water solution. After sample treatment and without any extended cleanup steps and derivatization process, four standard additions were performed for each sample. A specific PARAFAC model was built from three-way arrays formed by excitation–emission spectra and 5 measurements (sample plus 4 additions). The scores related to AFB1 were used for a linear regression in the standard addition method. Two naturally contaminated wheat and spiked wheat samples containing AFB1 in the range 0–18 μg kg−1 were analyzed by EF-SOSAM and compared with HPLC results. EF-SOSAM analysis of spiked wheat samples gave a good correlation with spiked values (R2 > 0.990). The limit of detection of method was 0.9 μg kg−1 for the determination of AFB1 in wheat samples.