A label free colorimetric assay for detection of sulfite root based on Cu2+

Abstract

The reaction between sulfite and hydrogen peroxide causes the absorbance decrease, which provides the basis to determine the sulfite content that is sensitive to the absorbance change. Cu2+ can catalyze the chemical reaction between hydrogen peroxide (H2O2) and the 2,2’-Azinobis-(3-ethylbenzothiazoline-6-sulphonate) (ABTS) effectively, which will cause the change of absorbance. In this paper, we presented an experiment system to study the influence of pH value, H2O2 content, Cu2+ content and reaction time on the reaction system. The comparison of experiment system results indicated that the optimal condition was pH value of 7.0, H2O2 of 500 μM, Cu2+ of 250 μM and 5 minutes reaction time. Under the optimal conditions, the absorbance (Y) and SO32- content (C) have a linear relationship Y=-861.35C+0.8923. The coefficient of determination (R2) in the linear relationship is 0.9983, which indicates a strong correspondence between C and Y. Then, the established method was used to detect the sulfite in wine. The recovery rate was between 96.01% and 106.90%, which proves this method is efficient for sulfite determination.