In-line electrochemical reagent generation coupled to a flow injection biamperometric system for the determination of sulfite in beverage samples

This work reports an in-line electrochemical reagent generation coupled to a flow injection biamperometric procedure for the determination of SO32−. The method was based on a redox reaction between the I3− and SO32− ions, after the diffusion of SO2 through a gas diffusion chamber. Under optimum experimental conditions, a linear response ranging from 1.0 to 12.0 mg L−1 (R = 0.9999 and n = 7), a detection and quantification limit estimated at 0.26 and 0.86 mg L−1, respectively, a standard deviation relative of 0.4% (n = 10) for a reference solution of 4.0 mg L−1 SO32− and sampling throughput for 40 determinations per hour were achieved. Addition and recovery tests with juice and wine samples were performed resulting in a range between 92% and 110%. There were no significant differences at a 95% confidence level in the analysis of eight samples when comparing the new method with a reference procedure.