Amperometric Sensor for Selective On-Site Analysis of Free Sulfite in Wines
Július Gajdár, Grégoire Herzog, Mathieu Etienne
Abstract
Accurate and rapid on-site analysis of free SO2 content is crucial in the process of winemaking from a producer and consumer perspective. Herein, we present an amperometric sensor based on commercially available screen-printed electrodes coupled with an electrochemical oxygen filter. The developed amperometric method gave a linear response in a concentration range up to 200 mg L–1 with a limit of quantification of 7.5 mg L–1. The applicability of the developed sensor was successfully tested on 27 white and red wine samples and compared to the Ripper method (iodometry) that is a standard procedure for free SO2 determination. The sensor exhibits similar precision and accuracy but shows no interference from oxidizable species such as ascorbic acid, which is a major advantage over iodometric titration. The performance of the sensor was in addition positively evaluated during on-site analysis in a winery.