Division 3 Procedure

Weigh into a beaker a quantity of product corresponding to $\frac{300}{R}g$ , ± 0,01 g where R represents the NTSS (natural total soluble solids) content. Add between 100 and 150 ml water. Mix well. Pour into the 2-litre separating funnel, which should be partly filled with water, and set the adjustable tube so that its lower end is at least half-way down the bulb. Allow water to flow into the funnel at a rate that causes sufficient turbulence to separate the mineral substances from the pulp. Remove the pulp in suspension without removing the sand; for this purpose the adjustable tube should be lowered towards the bottom of the separating funnel.

Continue the operation until only the mineral impurities remain at the bottom of the funnel. Note that the residue may sometimes also contain heavy organic waste such as tomato seeds.

Place the separating funnel over a funnel having an ashless filter and strain all the residue through the filter opening the separating funnel tap and flushing out as necessary with water. Rinse the filter with distilled water, then place the filter paper and residue in the incinerating dish. Dry the dish, residue and filter, then char over a low flame and finally incinerate in the muffle furnace at 500 to 600 °C for 30 minutes.

Allow to cool in the dryer and weigh accurately to within 0,0002 g.

At least two determinations must be carried out on the sample. The percentage by mass of mineral impurities is given by,

,

where:

• M₀ is the mass of the dish in grams,

• M₁ is the mass of the dish and ash in grams,

• E represents the dry weight content of the sample.