VOLATILE ACIDITY (GARCIA-TENA METHOD)
MATERIAL AND REAGENTS
1. Open the water network valve in order to start the cooling process and switch the front button on, button’s light will shine.
2. Place under the cooler the 5.1ml cylinder.
3. Measure 11 ml of the wine sample to analyze and drop into the distillation flask together with 1-2 granules of silicone pumice stone.
4. Place the flask in the grinded joint holding it with the metallic clamp and rotate to place it over the heater.
5. After few moments boiling process begins and when 5.1ml are collected in the cylinder (#1) it is swaped by the 3.2ml cylinder (#2) taking care not to loose any drop. If you use the Tenamatic GAB this process is automatically made so you don't need to take care about.
6. Once the distillation is finished withdraw the flask taking it by the metallic clamp and separate it by pulling to the front. You don’t need to touch the blue plastic clamp. If more analysis must be done the heater will not be switched off with the button in order to maintain the heater temperature.
7. The 3.2 ml cylinder distilled liquid is dropped in a 100 ml erlenmeyer flask in which a few drops of phenolphtalein solution will be added. It is titrated with sodium hidroxide N/49 untill the pinkish colour persists.
8. For a better titration it is dropped a little proportion of distilled liquid from the beaker to the cylinder and again it is dropped to the beaker. If decoloration appears more reagent will be added. write down the N mililiters spent.
9. Calculation: multiply the spent millilitres in the burette by the 0.366 factor and will be obtained the grams per litre of acetic acid (gr./L acetic acid, Real Volatile Acidity). g/l Real Acetic Acid = N' x 0,366
To know the apparent volatile acidity you will need to titrate the liquid contained in the 5,1 cylinder following the same instruccions and writting down the N' mililiters spent. (N x 0.366) + (N' x 0.122) = g/l Apparent Acétic Acid
Cylinders, flask and reagents are provided with the ELECTRIC VOLATIMETER GAB