SC-100A manual
6
Version 3.1c
12.
The free SO
2
content is calculated in units of parts per million (ppm) or mg/L as
ppm SO
2
=
64 * V * N * 1000
Where V = mL Titrant used to reach the endpoint; N = normality of the Titrant, and S = mL
wine sample
1
. If you use 25 mL of sample as directed, and the Titrant is 0.0156 N as supplied,
then the calculation is simply
ppm Free SO
2
= 20 * V
(i.e. 20 times V)
Measuring Total SO
2
by Titration (optional - requires 1N NaOH):
1.
Place 25 mL wine or must in the titration beaker (See Figure 5).
2.
Add 10ml 1N sodium hydroxide (Vinmetrica Part number SC-100-17) and mix well. Let stand
approximately 10 minutes.
3.
Using the transfer pipettes, add approximately 8 mL of the Acid Reagent and 2 mL of the Reactant
solution to the vessel. Remember that if you are using the transfer pipettes in the kit, 2 mL is
marked on the side of the neck of the transfer pipette, so dispense four of these for the Acid
Reagent.
4.
Proceed from step 5 in the Free SO
2
procedure above. The result calculated will be total SO
2
,
rather than free SO
2
in parts per million (ppm) or mg/L.
Finishing up:
1.
Turn off the instrument and unplug the electrode.
2.
Rinse the SO
2
electrode and syringe with distilled water. Let air dry.
3.
Store all reagents tightly capped and away from heat and sunlight.
4.
Discard waste samples and solutions in accordance with local regulations. Acidic solutions can be
neutralized by slow addition of baking soda (sodium bicarbonate) with stirring until effervescence
ceases.
1
The complete equation is:
64 [mg SO
2
/mmol SO
2
]* V [mL] * N [meq/mL] * 1000 [mL/L]
2 [meq/mmol SO
2
] * S [mL]
2 * S
