Spectrofluorimetric determination of benzoimidazolic pesticides: effect of p-sulfonatocalix[6]arenes and cyclodextrins

N. L. PACIONI,; V. N. SUELDO OCCELLO; M. LAZZAROTTO; A. V. VEGLIA*

ANALYTICA CHIMICA ACTA

Elsevier

Lugar: Ireland; Año: 2008 vol. 624 p. 133 - 133

0003-2670

he effect of the addition of a macrocyclic host (H) such as p-sulfonatocalix[6]arene (C6S), native and modified cyclodextrins (CDs), on the fluorescence of benzoimidazolic fungicides (P), like Benomyl (BY) and Carbendazim (CZ), has been studied. The fluorescence of BY in water at pH 1.000 and 25.0 C was increased in the presence of C6S, CD and hydroxypropyl--CD (HPCD). The association constants determined by fluorescence enhancement showed weak interactions (KA = 101 to 102 M−1) between the fungicide with both CDs, whereas they were stronger with C6S (KA = 105 M−1). Molecular recognition of BY for C6S was mainly attributed to electrostatic interactions, and for CDs to the hydrophobic effect and hydrogen bond formation. On the other hand, the fluorescent behaviour of CZ in the presence of C6S at pH 6.994 was interpreted as the formation of two complexes with 1:1 (P:H) and 1:2 (P:H2) stoichiometry, the latter being less fluorescent than the free analyte. Relative fluorescenc