Determination of free sulfur dioxide in cider

CDR CiderLab: the analysis system for cider to perform quality and process controlsSulfur 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 cider 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 cider from oxidizing alterations and from some micro-organisms. This test can be used to determine the fraction of free SO2.

The Analyzers CDR CiderLab for determining Free sulfur dioxide in Cider

The system is supplied pre-calibrated and ready for use.
Results are expressed in accordance with the reference method.
The reagents have a shelf-life untill 18 months
The analytical methods are simple: the system does not require an equipped laboratory or skilled staff.

 CDR CiderLab analyzeCDR CiderLabCDR CiderLab analyzer Junior VersionCDR CiderLab JUNIOR
AnalysesFermentable Sugars
Total Acidity
Acetic Acid
L-Lactic Acid
L-Malic Acid
Free sulfur dioxide (Free SO2)
Total sulfur dioxide (Total SO2)
Yeast assimilable nitrogen (YAN)
TPI – Total Polyphenols Index
Configuration with tailored panel of analyses
Simultaneous Sample Analyses163
Multiple Analyses on a Samplesi


Test type: kinetic.
Testing time: one test 3 minutes – 60 Tests/hour.
Are possible test sessions with several samples, up to a maximum of 16.

Calibration curve

The calibration curve of CDR CiderLab, obtained using reference methods.

Free Sulfur dioxide analysis in cider: correlation curve with reference method results

Test Principle

SO32- + RSSR <—–> RSSO3– + RS-.
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.

Reagent test Kits

The reagents are packaged in foil pouches containing 10 tubes useful to perform 10 analyses.

This is the minimum package that allows the use of CDR systems even to those who need to make a few analyses, thus not wasting reagents.

There are also boxes of 100 tests, however, packaged in 10 bags of 10 tubes containing the reagent.

Code *300345 – The kit, designed for 10 tests

Code *300333 – The kit, designed for 100 tests

The reagents have a shelf-life of 18 months.

Processing – Sample Volume – Measuring Range direction

Use the cider as is.

TestMeasuring range
(mg/L SO2)
Sample volumeResolutionRepeatability
Free SO21 – 6025 µL11,5 mg/L

Reagent developed by CDR S.r.l - ISO 9001 certified company

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Free sulfur dioxide was last modified: May 23rd, 2017 by CDR s.r.l.