Calcium Sulphate
(Ph. Eur. monograph 0982)
CaSO4,2H2O 172.2 10101-41-4
Action and use
Excipient.
DEFINITION
Content
98.0 per cent to 102.0 per cent of CaSO4,2H2O.
CHARACTERS
Appearance
White or almost white fine powder.
Solubility
Very slightly soluble in water, practically insoluble in ethanol (96 per cent).
IDENTIFICATION
A. Loss on ignition (see Tests).
B. Solution S (see Tests) gives reaction (a) of sulfates (2.3.1).
C. Solution S gives reaction (a) of calcium (2.3.1); use methylene chloride R instead of chloroform R for the extraction.
TESTS
Solution S
Dissolve 1.0 g in 50 mL of a 10 per cent V/V solution of hydrochloric acid R by heating at 50 °C for 5 min. Allow to cool.
Acidity or alkalinity
Shake 1.5 g with 15 mL of carbon dioxide-free water R for 5 min. Allow to stand for 5 min and filter. To 10 mL of the filtrate add 0.1 mL of phenolphthalein solution R and 0.25 mL of 0.01 M sodium hydroxide. The solution is red. Add 0.30 mL of 0.01 M hydrochloric acid. The solution is colourless. Add 0.2 mL of methyl red solution R. The solution is reddish-orange.
Chlorides (2.4.4)
Maximum 300 ppm.
Shake 0.5 g with 15 mL of water R for 5 min. Allow to stand for 15 min and filter. Dilute 5 mL of the filtrate to 15 mL with water R.
Iron (2.4.9)
Maximum 100 ppm.
To 0.25 g add a mixture of 5 mL of hydrochloric acid R and 20 mL of water R. Heat to boiling, cool and filter.
Loss on ignition
18.0 per cent to 22.0 per cent, determined on 1.000 g by ignition to constant mass at 800 ± 50 °C.
ASSAY
Dissolve 0.150 g in 120 mL of water R. Carry out the complexometric titration of calcium (2.5.11).
1 mL of 0.1 M sodium edetate is equivalent to 17.22 mg of CaSO4,2H2O.
FUNCTIONALITY-RELATED CHARACTERISTICS
This section provides information on characteristics that are recognised as being relevant control parameters for one or more functions of the substance when used as an excipient (see chapter 5.15). Some of the characteristics described in the Functionality-related characteristics section may also be present in the mandatory part of the monograph since they also represent mandatory quality criteria. In such cases, a cross-reference to the tests described in the mandatory part is included in the Functionality-related characteristics section. Control of the characteristics can contribute to the quality of a medicinal product by improving the consistency of the manufacturing process and the performance of the medicinal product during use. Where control methods are cited, they are recognised as being suitable for the purpose, but other methods can also be used. Wherever results for a particular characteristic are reported, the control method must be indicated.
The following characteristics may be relevant for calcium sulfate dihydrate used as filler in tablets and capsules.
