Determination of free sulfur dioxide in wine

Sulfur dioxide (SO2) is used in oenology mainly as preservative, but also for other purposes (for example for antiseptic, antioxidant, antioxidasic, solubilizing, combining and clarifying functions).

Part of the SO2 that is added as potassium metabisulfite to musts and wines undergoes a series of reactions.

Therefore, after a short period of time, most of the sulfur dioxide reacts with some of the substances present, binds with them and forms addition compounds (combined sulfur dioxide) that are unable to express the typical properties of unbound molecules.

Therefore, only the part that does not combine (free sulfur dioxide) plays an important role in preserving wine from oxidizing alterations and from some micro-organisms.

This test can be used to determine the fraction of free SO2.

Method

Test Principle

Chemical reaction involved in the determination of free sulfur dioxide in wine and must


The free fraction of sulfur dioxide is made to react with an organic disulphide in order to form a colored compound, whose intensity, measured at 420 nm in kinetics, is directly proportional to the concentration of free sulfur dioxide in the sample.

Calibration curve

The calibration curve of CDR WineLab®, obtained using reference methods.

Correlation curve with the reference method for the analysis of free sulfur dioxide in wine and must. R² = 0.968

Reagent test Kits

Measuring range

AnalysesMeasuring rangeResolutionRepeatability

Analyzers for process and quality control in winemaking

image

CDR WineLab®

  • Complete analysis panel, supplied already configured
  • Up to 16 determinations simultaneously
  • Possibility of carrying out analyses of the same sample
  • Integrated printer
  • Full connections (LAN - USB - Bluetooth barcode/QR code reader)
image

CDR WineLab® Junior

  • Partial analysis panel, supplied configured with 3 analyses of your choice, implementable
  • Up to 3 determinations simultaneously
  • Wireless connection to external printer
  • USB connections