Microanalytical flow system for the simultaneous determination of acetic acid and free sulfur dioxide in wines.

Free sulfur dioxide and volatile acidity are parameters related to the quality of wines. Traditional methods for their determination are tedious, time consuming and require analysis in decentralized laboratories, therefore corrective actions cannot be applied on time. This may be more complex in aging wine cellars, where hundreds of individual barrels containing almost finished wines should be monitored. To achieve this aim, a portable microanalytical flow system for the simultaneous detection of free SO and acetic acid during the ageing of wines is proposed in this work. The miniaturized system is based on the use of a gas-diffusion membrane and a pH-ISFET, and can be easily installed in barrels. The system was optimized in the range of 5-60 mg L and 0.15-1.40 g L for SO and acetic acid, respectively. It was validated with different sets of wine samples by comparing the results with standard methods, demonstrating a good agreement between methods.