Determination of Benzidine Using Sulfobutyl-beta-Cyclodextrin and Neutral Red Complexation as a Supermolecule Probe

Sulfobutyl-beta-cyclodextrin could remarkably decrease the fluorescence intensity of Neutral Red. In contrast, fluorescence intensity of Neutral Red enhanced efficiently when benzidine was present. Consequently, based on the competitive interaction between benzidine and Neutral Red, a new fluorescence spectrographic method of the determination of benzidine was established using sulfobutyl-beta-cyclodextrin and Neutral Red as a supermolecule probe in B-R buffer solution (pH 2.75). The linear range was from 2.00times10^-8 mol/L to 1.80times10^-7 mol/L, the limit of detection was 2.61times10^-8 mol/L. It is indicated that this method had high sensitivity, good selectivity and convenient application. This method had been applied to the determination of benzidine in industry waste water. A preliminary discussion was also given on the mechanism of the fluorescence reaction system.