Determination of free and total sulphur dioxide in wine by use of an amalgamated piezoelectric sensor

Abstract

A piezoelectric quartz crystal where the gold electrode is amalgamated with mercury is proposed as a sensor for sulphur compounds. The sensor is selective towards such compounds in both the vapour phase (particularly SO 2 and H 2S) and liquid phase. The dependence of its responsiveness to SO 2 on the mercury concentration, amalgamation conditions and experimental procedure is discussed. The sensor is especially stable under continuous-flow conditions. For application to the determination of free and bound sulphur dioxide in wine, a continuous-flow manifold was developed with a view to combine sample treatment and detection on-line. The results thus obtained were favorably compared with those provided by the Ripper recommended method. The reproducibility of analyses of real wine samples was better than 3.5% and recoveries ranged from 98 to 103%.