Talc is a powdered, selected, natural, hydrated magnesium silicate. Pure talc has the formula Mg3Si4O10(OH)2. It may contain variable amounts of associated minerals among which chlorites (hydrated aluminum and magnesium silicates), magnesite (magnesium carbonate), calcite (calcium carbonate), and dolomite (calcium and magnesium carbonate) are predominant.
Identification:
A: The IR spectrum of a potassium bromide dispersion of it exhibits maxima at 3677 ± 2 cm –1, at 1018 ± 2 cm–1, and at 669 ± 2 cm–1.
B: Mix about 200 mg of anhydrous sodium carbonate with 2 g of anhydrous potassium carbonate, and melt in a platinum crucible. To the melt add 100 mg of the substance under test, and continue heating until fusion is complete. Cool, and transfer the fused mixture to a dish or beaker with the aid of about 50 mL of hot water. Add hydrochloric acid to the liquid until effervescence ceases, then add 10 mL more of the acid, and evaporate the mixture on a steam bath to dryness. Cool, add 20 mL of water, boil, and filter the mixture: [NOTE—Save the insoluble residue for use in Identification test C.] To 5 mL of the filtrate add 1 mL of 6 N ammonium hydroxide and 1 mL of ammonium chloride. Filter, if necessary, and add 1 mL of dibasic sodium phosphate to the filtrate: a white crystalline precipitate of magnesium ammonium phosphate is formed.
C: In a lead or platinum crucible and using a copper wire, mix about 100 mg of the insoluble residue as obtained in Identification test B with about 10 mg of sodium fluoride and a few drops of sulfuric acid to give a thin slurry. Cover the crucible with a thin transparent plate of plastic under which a drop of water is suspended, and warm gently. Within a short time, a white ring is rapidly formed around the drop of water.
Microbial limits: If intended for topical administration, the total aerobic microbial count does not exceed 100 cfu per g, and the total combined molds and yeasts count does not exceed 50 cfu per g. If intended for oral administration, the total aerobic microbial count does not exceed 1000 cfu per g, and the total combined molds and yeasts count does not exceed 100 cfu per g.
Acidity and alkalinity: Boil 2.5 g of Talc with 50 mL of carbon dioxide-free water under reflux. Filter under vacuum. To 10 mL of the filtrate, add 0.1 mL of bromothymol blue. Not more than 0.4 mL of 0.01 N hydrochloric acid is required to change the color of the indicator. To 10 mL of the filtrate, add 0.1 mL of phenolphthalein: not more than 0.3 mL of 0.01 N sodium hydroxide is required to change the color of the indicator to pink.
Loss on ignition: Weigh accurately about 1 g, and ignite at 1075 ± 25C to constant weight: it loses not more than 7.0% of its weight.
Water-soluble substances: To 10.0 g add 50 mL of carbon dioxide-free water, heat to boiling, and boil under a reflux condenser for 30 minutes. Allow to cool, filter, and dilute with carbon dioxide-free water to 50.0 mL: the filtrate is neutral to litmus paper. Evaporate 25.0 mL of the filtrate to dryness, and dry at 105C for 1 hour: the weight of the residue does not exceed 5 mg (0.1%).
Limit of iron: To pass the test.
Limit of lead: To pass the test.
Limit of calcium: To pass the test.
Limit of aluminum: : To pass the test.
Absence of asbestos: To pass the test.
Content of magnesium: To pass the test.
Talc, Ph Eur --- 14807-96-6
DEFINITION
Powdered, selected, natural, hydrated magnesium silicate. Pure talc has the formula Mg3Si4O10(OH)2 (M r 379.3). It may contain variable amounts of associated minerals among which chlorites (hydrated aluminium and magnesium silicates), magnesite (magnesium carbonate), calcite (calcium carbonate) and dolomite (calcium and magnesium carbonate) are predominant.
PRODUCTION
Talc derived from deposits that are known to contain associated asbestos is not suitable for pharmaceutical use. The manufacturer is responsible for demonstrating by the test for amphiboles and serpentines that the product is free from asbestos. The presence of amphiboles and of serpentines is revealed by X-ray diffraction or by infrared spectrophotometry (see A and B). If detected, the specific morphological criteria of asbestos are investigated by a suitable method of optical microscopy to determine whether tremolite asbestos or chrysotile is present, as described below.
A. Infrared absorption spectrophotometry.
B. X-ray diffraction.
CHARACTERS
Appearance: Light, homogeneous, white or almost white powder, greasy to the touch (non abrasive).
Solubility: Practically insoluble in water, in ethanol (96 per cent) and in dilute solutions of acids and alkali hydroxides.
IDENTIFICATION
First identificationi A.
Second identificationi B, C.
A. Infrared absorption spectrophotometry.
Absorption bandsi At 3677 ± 2 cm-1, 1018 ± 2 cm-1 and 669 ± 2 cm-1.
B. In a platinum crucible, melt a mixture of 0.2 g of anhydrous sodium carbonate and 2.0 g of potassium carbonate. To the melted mass add 0.1 g of the substance to be examined and heat until the mixture is completely melted. Allow to cool and transfer the melted mass into an evaporating dish with 50 ml of hot water. Add hydrochloric acid until effervescence ceases. Add 10 ml of hydrochloric acid and evaporate to dryness on a water-bath. Allow to cool. Add 20 ml of water, heat to boiling and filter (the residue is used for identification test C). To 5 ml of the filtrate add 1 ml of ammonia and 1 ml of ammonium chloride solution and filter. To the filtrate add 1 ml of disodium hydrogen phosphate solution. A white, crystalline precipitate is formed.
C. The residue obtained in identification test B gives the reaction of silicates.
TESTS
Solution S1: Weigh 10.0 g into a conical flask fitted with a reflux condenser, add 50 ml of 0.5 M hydrochloric acid gradually while stirring and heat on a water-bath for 30 min. Allow to cool. Transfer the mixture to a beaker and allow the undissolved material to settle. Filter the supernatant through medium-speed filter paper into a 100 ml volumetric flask, retaining as much as possible of the insoluble material in the beaker. Wash the residue and the beaker with 3 quantities, each of 10 ml, of hot water. Wash the filter with 15 ml of hot water, allow the filtrate to cool and dilute to 100.0 ml with the same solvent.
Solution S2: Perchlorates mixed with heavy metals are known to be explosive. Take proper precautions while performing this procedure. Weigh 0.5 g in a 100 ml polytetrafluoroethylene dish, add 5 ml of hydrochloric acid, 5 ml of lead-free nitric acid and 5 ml of perchloric acid. Stir gently then add 35 ml of hydrofluoric acid and evaporate slowly to dryness on a hot plate. To the residue, add 5 ml of hydrochloric acid, cover with a watch-glass, heat to boiling and allow to cool. Rinse the watch-glass and the dish with water. Transfer into a volumetric flask, rinse the dish with water and dilute to 50.0 ml with the same solvent.
Acidity or alkalinity: Boil 2.5 g with 50 ml of carbon dioxide-free water under reflux. Filter in vacuo. To 10 ml of the filtrate add 0.1 ml of bromothymol blue solution; not more than 0.4 ml of 0.01 M hydrochloric acid is required to change the colour of the indicator to green. To 10 ml of the filtrate add 0.1 ml of phenolphthalein solution; not more than 0.3 ml of 0.01 M sodium hydroxide is required to change the colour of the indicator to pink.
Water-soluble substances: Maximum 0.2 per cent.
Aluminium: Maximum 2.0 per cent.
Calcium: Maximum 0.90 per cent.
Iron: Maximum 0.25 per cent.
Lead: Maximum 10.0 ppm.
Magnesium: 17.0 per cent to 19.5 per cent.
Loss on ignition: Maximum 7.0 per cent, determined on 1.00 g by ignition to constant weight at 1050-1100 °C.
Microbial contamination: If intended for topical administration, the total viable aerobic count is not more than a total of 100 bacteria and fungi per gram. If intended for oral administration, the total viable aerobic count is not more than 1000 bacteria and not more than 100 fungi per gram.
We also offer Purified Talc IP grade
Talc Dusting Powder BP Grade
DEFINITION
Talc Dusting Powder is a sterile cutaneous powder of suitable fineness consisting of 10% of starch and 90% of Purified Talc.
PRODUCTION
The starch is triturated with the Purified Talc and passed through a sieve of suitable mesh size (250 μm may be suitable). Either the Purified Talc is sterilised before use or the final product is subjected to a suitable sterilisation procedure.
The dusting powder complies with the requirements stated under Topical Powders and with the following requirement.
Acid-insoluble matter: 86.0 to 91.0% when determined by the following method. Boil 0.5 g with 10 ml of 2M hydrochloric acid for 5 minutes, cool, filter through a tared sintered-glass crucible (ISO 4793, porosity grade 4, is suitable), wash the residue with water until the washings are free from acid and dry to constant weight at 105C.
INS: 553(iii) CAS: [14807-96-6]
DESCRIPTION
Talc occurs as a white to gray-white, unctuous powder. It is a naturally occurring form of hydrous magnesium silicate containing varying proportions of such associated minerals as alpha-quartz, calcite, chlorite, dolomite, kaolin, magnesite and phlogopite. Talc derived from deposits that are known to contain associated asbestos is not food grade. It is insoluble in water and in solutions of alkali hydroxides, but is slightly soluble in dilute mineral acids.
REQUIREMENTS
Identification
A. The X-ray diffraction pattern of a random powder sample exhibits intense reflections at the following d values: 9.34A, 4.66 A, and 3.12 A .
B. The infrared absorption spectrum of a potassium bromide dispersion of the sample exhibits major peaks at approximately 1015 cm−1 and 450 cm−1.
Acid-Soluble Substances: (as SO4) Not more than 2.5%.
Arsenic: Not more than 3 mg/kg.
Free Alkali: (as NaOH) Not more than 1%.
Lead: Not more than 5 mg/kg.
Loss on Drying: Not more than 0.5%.
Loss on Ignition: Not more than 6.0%.
Soluble Salts: Not more than 0.2%.
