Edition: BP 2025 (Ph. Eur. 11.6 update)
General Notices
(Ph. Eur. monograph 0120)
HgCl2 271.5 7487-94-7
Ph Eur
DEFINITION
Content
99.5 per cent to 100.5 per cent (dried substance).
CHARACTERS
Appearance
White or almost white, crystalline powder or colourless or white or almost white crystals or heavy crystalline masses.
Solubility
Soluble in water and in glycerol, freely soluble in ethanol (96 per cent).
IDENTIFICATION
A. It gives reaction (a) of chlorides (2.3.1).
B. Solution S (see Tests) gives the reactions of mercury (2.3.1).
TESTS
Solution S
Mercuric Chloride
Dissolve 1.0 g in carbon dioxide-free water R and dilute to 20 mL with the same solvent.
Appearance of solution
Solution S is not more opalescent than reference suspension II (2.2.1) and is colourless (2.2.2, Method II).
Acidity or alkalinity
To 10 mL of solution S add 0.1 mL of methyl red solution R. The solution is red. Add 0.5 g of sodium chloride R. The solution becomes yellow. Not more than 0.5 mL of 0.01 M hydrochloric acid is required to change the colour to red.
Mercurous chloride
Dissolve 1.0 g in 30 mL of ether R. The solution shows no opalescence.
Loss on drying (2.2.32)
Maximum 1.0 per cent, determined on 2.00 g by drying in vacuo for 24 h.
ASSAY
Dissolve 0.500 g in 100 mL of water R. Add 20.0 mL of 0.1 M sodium edetate and 5 mL of buffer solution pH 10.9 R. Allow to stand for 15 min. Add 0.1 g of mordant black 11 triturate R and titrate with 0.1 M zinc sulfate until the colour changes to purple. Add 3 g of potassium iodide R, allow to stand for 2 min, add a further 0.1 g of mordant black 11 triturate R and titrate with 0.1 M zinc sulfate.
1 mL of 0.1 M zinc sulfate used in the second titration is equivalent to 27.15 mg of HgCl2.
STORAGE
Protected from light.
Ph Eur
