Abstract: The formation mechanism of ternary supra-molecular systems composed of aflatoxin M1 (AFM1), β-cyclodextrin or its derivatives (β-CDs) and Hg2+ was studied by measuring the native fluorescence of AFM1 and fluorescence changes of the β-CD-Hg2+-AFM1 system. The fluorescence intensity of the methyl-β-CD-Hg2+-AFM1 ternary supramolecular system in 20% (V/V) aqueous methanol with a molar ratio of Hg2+ to M-β-CD to AFM1 of 6.6 × 104:5.80 × 105:1 could be 4.5 times higher than that of the native fluorescence intensity of AFM1. It was proved that AFM1 entered the cavity of M-β-CD, leading to reduced fluorescence quenching and increased sensitivity of detection by spectroscopic and thermodynamic analyses. Supermolecular inclusion constants and thermodynamic constant were calculated and the superamolecular reaction mechanism was studied preliminarily by the Benesi-Hidebrand equation and Van’t Hoff equation. Good linearity was observed in the AFM1 concentration range of 0.01–2.00 μg/L with a correlation coefficient of 0.999 2 and the detection limit of this method was 0.002 6 μg/L. The method could be used in the rapid detection of AFM1 in dairy products with high sensitivity. It was simple, efficient and economical without interference from most fortified trace minerals except Fe3+ in dairy products.

Key words: aflatoxin M1, supramolecular system, fluorescence enhancement, fast detection, inclusion