Total sulphur dioxide represents the sum of free and bound sulphur dioxide. bound so2 is that which is bonded to so-called sulphur acceptors (aldehydes, pyruvates, anthocyanins). In general, sulphur dioxide is used in oenology in different phases of wine production thanks to its antioxidant and antimicrobial properties.

Total SO2 = free SO2 + bound SO2

SO2 is determined by means of iodometric titration.

This method often overestimates the real content of SO2 because iodium also reacts with other molecules present in the wine that constitute interferents for this method (ascorbic acid, polyphenols, colouring etc.).