Immobilization of cyclodextrin for the determination of benzimidazole fungicides

Abstract

Cyclodextrins (CDs), the cyclic oligosaccharides play an important role in the inclusion complex technology. Its application in analytical chemistry with both chromatographic and non-chromatographic methods is remarkably increased, especially, the development of CDs as molecular sensors. In this study, the use of immobilized CD on microtiter plate and the competitive benzimidazole tracer encapsulation approach were employed and developed for the determination of benzimidazole fungicides. A specialized technique for CD immobilization on a microtiter plate was first developed. The result indicated that CD could be immobilized on microtiter plate by the use of divinylsulfone as a cross-linking reagent and the immobilized CD could entrap benzimidazole tracer. The optimization of benzimidazole tracer for the encapsulation into immobilized CD was determined. It was found that the optimal condition was the use of 2.5 mu g/ml benzimidazole tracer for the encapsulation into amino microtiter plate coated with 5% beta-CD, incubated for 1 hour at 25 ํC and 0.1 M acetate/citric acid buffer, pH 5 as washing buffer. The capability test of competitive benzimidazole tracer encapsulation was examined by the use of carbendazim standard and spiked sample solution. The result indicated that the approach could be used for carbendazim detection in grape extract at approximately 3 ppm, which was the minimum concentration completely inhibited benzimidazole tracer encapsulation. Although, the approach showed the lower sensitivity than ELISA method, it could be available for screening purpose and could be further improved for quantitative determination of carbendazim and other related compounds under specific condition