An In Vitro Comparative Study of Aflatoxin B1 Adsorption by Thai Clay and Commercial Toxin Binders

Twenty samples of Thai clay from fourteen provinces and seven commercial toxin binders were investigated for their adsorption capacity of aflatoxin B1 (AFB(1)) in vitro. Each sample of 5 mg/l AFB(1) solution was shaken at 25 degrees C for 24 hours and supernatants of centrifuged samples were analyzed for concentrations of AFB(1) using a UV spectrophotometer. Adsorption capacity was calculated and applied to isothermic equations. The results indicated that Thai clays was capable of sequestering AFB(1) from aqueous solution differently and Thai clay from Lopburi and Lamphun provinces had the highest adsorption capacity, similar to commercial binders. S-shaped isothermic curves were observed for all samples having adsorption capacity greater than 4 x 10(-3) mol/kg. These isothermic data were fitted using a modified Freundlich model that suggested that the samples possessed multilayered or multiple adsorption sites for the toxin. The clay from Lopburi and Lamphun had maximum adsorption capacity (Q(max)) of 4.76 x 10(-3) mol/kg and 4.68 x 10(-3) mol/kg, respectively, whereas the commercial binders had Q(max) that ranged from 4.38 x 10(-3) mol/kg to 5.07 x 10(-3) mol/kg. Inductive couple plasma spectrometry and X-ray diffraction spectrometry of the clay samples demonstrated that the clay from Lopburi and Lamphun contained montmorillonite as a major component, similar to the bentonites. It was concluded that Thai clay from Lopburi and Lamphun provinces could absorb AFB(1) in vitro efficiently, similar to commercial toxin binders.