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

•The reagent generation (I3−) in line ensures stability of the pair redox I3−/I−.•The use of a gas diffusion cell minimizes interferences present in the samples.•The simplicity and precision of the biamperometric system is suitable for use with real 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 12.0mgL−1 (R=0.9999 and n=7), a detection and quantification limit estimated at 0.26 and 0.86mgL−1, respectively, a standard deviation relative of 0.4% (n=10) for a reference solution of 4.0mgL−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.