Activated Carbons: In Vitro Affinity for Aflatoxin B1 and Relation of Adsorption Ability to Physicochemical Parameters

Abstract

Affinity in vitro tests were conducted of the efficacy of 17 activated carbons (ACs) in binding aflatoxin B1 from solution. Relationships between adsorption ability and physicochemical parameters of the ACs (surface area, iodine number, methylene blue index, and surface acidity) were tested. Using 5 ml of a 4 μg/ml aqueous solution of aflatoxin B1 and 2 mg of an AC, adsorption abilities ranged from 44.47% to 99.82%. Four ACs showed very high adsorption abilities, binding more than 99% of the available aflatoxin B1. In comparative testing five ACs showed a greater ability to bind aflatoxin B1 than hydrated sodium calcium aluminosilicate (HSCAS). Three ACs also showed high adsorption abilities (ca. 99%) at increasing aflatoxin B1 concentrations (50 and 250 μg/ml) whereas HSCAS adsorption ability greatly declined. With the exception of three ACs, aflatoxin B1 adsorption was significantly correlated with all the physicochemical parameters, confirming a close relationship between molecule trapping and the surface physicochemical adsorption process. The methylene blue index was more reliable than iodine number and surface area in predicting AC adsorptive ability. The results suggested that ACs with a high methylene blue index and low surface acidity have a very high in vitro affinity for aflatoxin B1; however, their efficacy in protecting against aflatoxicosis should be verified further by in vivo tests.