A novel spectrofluorometric method for the determination of methiocarb using an amphiphilic p-sulfonatocalix[4]arene

The characteristics of host–guest complexation between tetrabutyl ether derivatives of p-sulfonatocalix[4]arene (SC4Bu) and methiocarb [3,5-dimethyl-4-(methylthio) phenyl methylcarbamate] were investigated by fluorescence spectrometry. Upon addition of methiocarb, the fluorescence intensity of SC4Bu was quenched regularly and a slight red shift was observed for the maximum emission peak. These results indicated that the SC4Bu-methiocarb complex was formed a 1:1 mole ratio. An association constant of 1.67 × 104 L mol−1 was calculated by applying a deduced equation. The interaction mechanism of the inclusion complex was discussed. Based on the results, a novel spectrofluorimetric method was described for the determination of methiocarb with a detection limit at 0.05 μg mL−1. This method is very simple and shows high sensitivity and selectivity. Moreover, the proposed method was successfully applied to the determination of methiocarb in water samples.

. The characteristics of host–guest complexation between tetrabutyl ether derivatives of p-sulfonatocalix[4]arene (SC4Bu) and methiocarb [3,5-dimethyl-4-(methylthio) phenyl methylcarbamate] were investigated by fluorescence spectrometry. A 1:1 stoichiometry for the complexation was established and was verified by Job's plot. The interaction mechanism of the inclusion complex was discussed. The quantum-mechanical molecular model was implemented in the Gaussian 03 program package.Figure optionsDownload as PowerPoint slideHighlights
► In this paper, the host–guest complex between SC4Bu and methiocarb were studied.
► A 1:1 stoichiometry for the complexation was established.
► The limit of detection is 0.05 μg mL−1.
► The relevant free energy change for this system is ΔG = −24.03 kJ mol−1 at 298 K.