Division 4 Procedure

Weigh into a 50-ml beaker a quantity of product corresponding to $\frac{300}{R}g$ , ± 0,01 g where R represents the NTSS (natural total soluble solids) content.

Transfer the sample to a 200-ml volumetric flask. Make up to 200 ml with boiled distilled water. Shake well. Filter. Remove 50 ml of filtrate and transfer to a squat beaker (400-ml minimum capacity). Add between 150 and 200 ml of boiled distilled water.

Using buffer solutions with pH values of about 8,0, check that the potentiometer is functioning correctly. Using the burette, add the sodium hydroxide solution (2.1) fairly quickly, while shaking, until the pH value is about 6,0. Add further solution slowly until the pH reaches 7,0. Then add further solution drop by drop, noting after each addition the volume of sodium hydroxide solution (2.1) and the pH value until a pH of 8,1 ± 0,2 is reached. Deduce, by interpolation, the exact volume of sodium hydroxide solution which corresponds to a pH value of 8,1.

At least two determinations must be carried out on the same prepared sample.