Hanna Instruments HI 84500 - Manual (Page 6)

6
PRINCIPLE OF OPERATION
The HI 84500 determines the free and total sulfur dioxide concentration in wine using the Ripper
method. Excess iodide added to the wine sample reacts with iodate introduced by the titrant to
produce iodine.
IO
3
- + 5I- + 6H
+ →
3I
2
+ 3H
2
O
The iodine produced in the sample then reacts with sulfur dioxide in the wine according to the redox
reaction below:
H
2
SO
3
+ I
2
→
H
2
SO
4
+ 2HI
The HI 84500 utilizes an ORP electrode to monitor the redox titration. The integrated algorithm
detects when the reaction is complete (equivalence point). The volume of titrant required to reach the
equivalence point, the titrant concentration and the sample size are used to calculate the sulfur
dioxide concentration in the wine sample.