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VIDEOS
SO2 measurement with Toning
SO2 measurement with Toning+
REQUIRED MATERIAL
GAB INOX BURETTE SUPPORT
BURETTE CLAMP WITH WALNUT
BURETTE 25 ml PTFE
PIPETTE 25 ml 2 marks "A"
PIPETTE 5 ml GRADUATED
PIPETTE 10 ml GRADUATED
ERLENMEYER 250 ml B / W
RUBBER PLUG
SULFUR SO2 ANALYSIS PACK
PIPETTE VACUUM CLEANER 25 ml RED
CHEMICAL CONCEPTS
The advantage of this method is to give a quick estimate of the SO2 content, making it an effective usual or routine method for daily use. It is applicable for all kinds of wines. It is based on the redox reaction in which sulfur dioxide (SO2) reacts with potassium iodine / iodate.
The use of a highly stable titration solution over time such as potassium iodate is novelty compared to the iodine solution.
Unreacted iodine / iodate turns dark blue in the presence of starch. The persistence of this for 10-15 sec. indicates the end of the analysis.
On the other hand, it is slightly less precise than aspiration (Paul-Rankine) for red wines since the iodate that reacts with the sample, partly reacts with SO2 and partly could be consumed by phenols, sugars, aldehydes and others. reducing substances, the amount of which varies depending on the composition of each wine.
OPERATIONAL TECNIQUE
FREE SO2:
1- Have a 25 ml burette filled and flush with SO2 GAB titration liquid.
2- In an erlenmeyer flask pour, without aerating, 25 ml of the wine to be analyzed, 1-2 ml of indicator starch and 5 ml of acid.
3- Place under the burette and titrate until you see a slightly bluish color that persists for 15-20 seconds.
4- Result: number of milliliters spent x 10 = mg / l free SO2
TOTAL SO2:
1- Proceed as point 1 of free SO2
2- In an erlenmeyer flask, pour 25 ml of wine to be analyzed, 10 ml of alkali, without aeration, shake without aeration, cover and leave to rest for 10 - 15 minutes.
3- Add 1 - 2 ml of indicator starch and 5 ml of acid.
4- Proceed as in point 3 of the free SO2.
5- Result: number of milliliters spent x 10 = mg / l SO2 Total
OBSERVATIONS
One of the advantages is that the result is found by multiplying the number of milliliters used by 10 (1 ml is equivalent to 10 mg / l of SO2, see table).
The turn tends towards a dark blue-purple color, hardly noticeable in red wines. You can enhance your observation by adding distilled water to the sample and using a desk light across the sample, or a shaker with a built-in light.
Caution should be taken not to touch the walls of the Erlenmeyer flask with the indicator pipet, since when the pipette is returned to the bottle it will contaminate the liquid and it will acquire a bluish color. You should also take into account not to change the packaging pipettes.
The end point is determined when the entire sample remains dark blue for about 10-15 seconds.
The Ripper method cannot be used if the wine contains ascorbic acid (Vitamin-C) since it reacts in large quantities with iodate, then use the SO2 Inhibitor ref. 1006012.
Use the multiplier table if you are using a different potassium iodine / iodate concentration or using a different sample volume:
|
TABLA DE COEFICIENTES MULTIPLICADORES | ||||||
|
VOLUMEN DE LA MUESTRA mL. | ||||||
|
10 |
15 |
20 |
25 |
50 |
100 | |
| YODO N/10 |
320 |
213 |
160 |
128 |
64 |
32 |
| YODO N/32 |
100 |
66.6 |
50 |
40 |
20 |
10 |
| YODO N/50 |
64 |
42.6 |
32 |
25.6 |
12.8 |
6.4 |
| YODO N/64 |
50 |
33.3 |
25 |
20 |
10 |
5 |
| YODO N/100 |
32 |
21.3 |
16 |
12.8 |
6.4 |
3.2 |
| YODO N/128 |
25 |
16.64 |
12.5 |
10 |
5 |
|