New reversed-phase liquid chromatographic method to detect aflatoxins in food and feed with cyclodextrins as fluorescence enhancers added to the eluent

The effect of succynil-beta -cyclodextrin (beta -CD-Su), dimethyl-beta -cyclodextrin (DIMEB) and beta -cyclodextrin (beta -CD) on the fluorescence of aflatoxins B-1, B-2, G(1), G(2) and M-1 (AFB(1), AFB(2), AFG(1), AFG(2) and AFM(1)) was studied: beta -CD-Su promoted the largest fluorescence enhancement for AFB(1) and AFM(1) while DIMEB showed better results for AFG(1). On the basis of the fluorescence enhancement, a new RP-HPLC method for detecting aflatoxins B-1, B-2, G(1), G(2) and M-1 was developed using cyclodextrins directly dissolved in the LC eluent. Aflatoxins B-1, B-2, G(1) and G(2) were resolved using a MICRA NPS ODS-1 column using methanol-water as mobile phase to which 6x10(-3) M beta -CD-Su or beta -CD were added. Chromatographic responses of AFB(1) and AFG(1) achieved using beta -CD dissolved in the mobile phase were enhanced, respectively, 8 and 12 times, and 10 and 15 times with beta -CD-Su. Detection limits lower than 0.3 mug/kg were achieved for all the four aflatoxins. Aflatoxin M-1 was analysed using a Spherisorb S3 ODS-2 Narrow Bore column and methanol-water as mobile phase with added 2x10(-3) M beta -CD-Su. An area enhancement of 1.5 was detected for the toxin and the detection Emit achieved under these analytical conditions was lower than 0.0005 mug/kg. Both methods were statistically validated showing a linear response for all the aflatoxins tested (R(2)greater than or equal to0.99), and applied to the analysis of spiked and naturally contaminated food samples. (C) 2001 Elsevier Science B.V. All rights reserved.