Mixture of particles with colloidal particle size of montmorillonite and saponite, free from grit and non-swellable ore. Content:
aluminium (Al; Ar 26.98): 95.0 per cent to 105.0 per cent of the value stated on the label.
magnesium (Mg; Ar 24.30): 95.0 per cent to 105.0 per cent of the value stated on the label.
CHARACTERS
Appearance: Almost white powder, granules or plates. Solubility: Practically insoluble in water and in organic solvents. It swells in water to produce a colloidal dispersion.
IDENTIFICATION
A. Fuse 1 g with 2 g of anhydrous sodium carbonate. Warm the residue with water and filter. Acidify the filtrate with hydrochloric acid and evaporate to dryness on a water-bath. 0.25 g of the residue gives the reaction of silicates. B. Dissolve the remainder of the residue obtained in identification test A in a mixture of 5 mL of dilute hydrochloric acid and 10 mL of water. Filter and add ammonium chloride buffer solution pH 10.0. A white, gelatinous precipitate is formed. Centrifuge and keep the supernatant for identification C. Dissolve the remaining precipitate in dilute hydrochloric acid. The solution gives the reaction of aluminium. C. The supernatant liquid obtained after centrifugation in identification test B gives the reaction of magnesium.
TESTS
pH: 9.0 to 10.0. Arsenic: Maximum 3 ppm. Lead: Maximum 15 ppm. Loss on drying: Maximum 8.0 per cent, determined on 1.000 g by drying in an oven at 105C. Microbial contamination: TAMC: acceptance criterion 1000 CFU/g. TYMC: acceptance criterion 100 CFU/g.
Absence of Escherichia coli.
