The mteractron between the four mam aflatoxms (G2, G,, B, and B,) and @yclodextrm (/3-cyd) was studied using reversed-phase hqmd chromatography (RP-LC) These aflatoxms are structurally very sumlar compounds that exhibit m RP-LC, and with methanol-water as eluent, a characterlstlc elutlon profile, 1 e , k,& < k&, < k& < k& In the presence of P-cyd m the eluent, this elutlon order remains constant and the decrease m all the capacity factors (k') IS used to calculate the respective complex formation constant (K,) of each compound with @-cyd, which are 263,327,215 and 258 1 mol-' for aflatoxms G,, G,, B, and B,, respectively The enthalpy (AZfB) and entropy (A$) changes associated Hrlth the mteractlon of the Cls support with the complexed solutes were extracted from the temperature dependance of k' All the established thermodynamic data strongly suggest the occurrence of a 1 1 stoichiometry inclusion process between the aflatoxms and the introduced P-cyd On the other hand, the discrepancy between some of the thermodynamic parameters (ASI and some of the chromatographlc parameters (k') suggests that the drrvlng forces involved m the chromatographlc partition process and m the mcluslon m the /3-cyd cavity may be due to different parts of the aflatoxm molecule Finally, the results obtained Hrlth the proposed method indicate that RP-LC can be successfully used to calculate complex formation constants and to contribute to a better mslght mto the p-cyd-aflatoxm interaction
Keywords
Liquid chromatography, Aflatoxms, Cyclodextrm, Inclusion compounds Aflatoxms B,, B,, G, and G, are the four mam Aspergdlus jlavus sp toxms Because of the well established cargmogemc and mutagenic potentlahty of these toxms, their determination at low levels (nM range), e g , m various foodstuffs, IS of major interest [1,2] Among the numerous pubhshed methods for then determmatlon (especlally chromatographlc and mununologlcal), reversed-phase liquid chromatography (RP-LC) coupled with fluonmetnc detection occupies an important posltlon because of the natural fluores-