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Carbasalate Calcium(Ph Eur monograph 1185)
C19H18CaN2O9 458.4 5749-67-7
Ph Eur
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Definition
Carbasalate calcium contains not less than 99.0 per cent and not more than the equivalent of 101.0 per cent of an equimolecular compound of calcium di[2-(acetyloxy)benzoate] and urea, calculated with reference to the anhydrous substance.
Characters
A white, crystalline powder, freely soluble in water and dimethylformamide, practically insoluble in acetone and in anhydrous methanol.
Protect the substance from moisture during handling. Examination in aqueous solutions has to be performed immediately after preparation.
Identification
First identification
B, E.
Second identification
A, C, D, E.
A. Dissolve 0.250 g in water R and dilute to 100.0 ml with the same solvent. To 1.0 ml of the solution add 75 ml of water R and 5 ml of dilute hydrochloric acid R, mix and dilute with water R to 100.0 ml. Examined immediately after preparation between 220 nm and 350 nm (2.2.25), the solution shows two absorption maxima, at 228 nm and 276 nm. The specific absorbances at the maxima are 363 to 379 and 49 to 53, respectively.
B. Examine by infrared spectrophotometry (2.2.24), comparing with the Ph. Eur. reference spectrum of carbasalate calcium.
C. Dissolve 0.1 g in 10 ml of water R, boil for 2 min and cool. The solution gives reaction (a) of salicylates (2.3.1).
D. Heat 0.2 g with 0.2 g of sodium hydroxide R; a yellow to yellowish-brown colour is produced and the vapour turns red litmus paper R blue.
E. It gives reaction (a) of calcium (2.3.1).
Tests
Appearance of solution
Dissolve 2.5 g in 50 ml of water R. The solution is not more opalescent than reference suspension II (2.2.1) and is colourless (2.2.2, Method II).
Related substances
In a 100 ml volumetric flask, dissolve 0.150 g in 10 ml of 0.1M tetrabutylammonium hydroxide in 2-propanol . Allow to stand for 10 min shaking occasionally. Add 8.0 ml of 0.1M hydrochloric acid and 20.0 ml of a 19 g/l solution of disodium tetraborate R and mix. While swirling continuously, add 2.0 ml of a 10 g/l solution of aminopyrazolone R and 2.0 ml of a 10 g/l solution of potassium ferricyanide R. Allow to stand for 2 min, dilute to 100.0 ml with water R, mix and allow to stand for 20 min. Measure the absorbance (2.2.25) of the solution at the maximum at 505 nm using water R as the compensation liquid. The absorbance is not greater than 0.125 (0.1 per cent, expressed as acetylsalicylsalicylic acid).
Salicylic acid
In a 100 ml volumetric flask, dissolve 0.200 g in 80 ml of water R and add 10 ml of a 10 g/l solution of ferric nitrate R in a 80 g/l solution of dilute nitric acid R. Dilute to 100.0 ml with water R. Immediately after preparation, measure the absorbance (2.2.25) of the solution at the maximum of 525 nm using water R as the compensation liquid. The absorbance is not greater than 0.115 (0.5 per cent, expressed as salicylic acid).
Sodium
Not more than 0.1 per cent, determined by atomic emission spectrometry (2.2.22, Method I) using 1.0 g dissolved in 500.0 ml of water R.
Heavy metals (2.4.8)
Dissolve 2.0 g in 8 ml of water R, with heating, cool and add 12 ml of acetone R. 12 ml of the solution complies with limit test B for heavy metals (10 ppm). Prepare the standard using 10 ml of lead standard solution (1 ppm Pb) R.
Water (2.5.12)
Not more than 0.1 per cent, determined on 1.000 g by the semi-micro determination of water. Use a mixture of 15 ml of anhydrous methanol R and 15 ml of dimethylformamide R as the solvent.
Assay
In a flask with a ground-glass stopper, dissolve 0.400 g in 25 ml of water R. Add 25.0 ml of 0.1M sodium hydroxide. Close the flask and allow to stand for 2 h. Titrate the excess of alkali with 0.1M hydrochloric acid, using 0.2 ml of phenolphthalein solution R. Carry out a blank titration.
1 ml of 0.1M sodium hydroxide is equivalent to 22.92 mg of C19H18CaN2O9.
Storage
Store in an airtight container .
Impurities
A. 2-(acetyloxy)benzoic anhydride,
B. 2-[[2-(acetyloxy)benzoyl]oxy]benzoic acid (acetylsalicylsalicylic acid),
C. 2-hydroxybenzoic acid (salicylic acid).
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Ph Eur
Action and use
[ 本帖最后由 patty-chu 于 2012-10-25 10:31 编辑 ]
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