Hydrochloric acid, concentrated EUROPEAN PHARMACOPOEIA 11.

IMPURITIES 2 min. Any blue colour disappears on the addition of 0.2 mL

Specified impurities : A, B. of 0.01 M sodium thiosulfate.
Other detectable impurities (the following substances would, Sulfates (2.4.13): maximum 20 ppm.
if present at a sufficient level, be detected by one or other of To 6.4 mL add 10 mg of sodium hydrogen carbonate R and
the tests in the monograph. They are limited by the general evaporate to dryness on a water-bath. Dissolve the residue
acceptance criterion for other/unspecified impurities and/or in 15 mL of distilled water R.
by the general monograph Substances for pharmaceutical use Residue on evaporation : maximum 0.01 per cent.
(2034). It is therefore not necessary to identify these impurities
for demonstration of compliance. See also 5.10. Control of Evaporate 100.0 g to dryness on a water-bath or using a rotary
impurities in substances for pharmaceutical use) : C, D. evaporator and dry the residue at 100-105 °C. The residue
weighs a maximum of 10 mg.
ASSAY
Weigh accurately a ground-glass-stoppered flask containing
30 mL of water R. Introduce 1.5 mL of the acid to be examined
and weigh again. Titrate with 1 M sodium hydroxide,
determining the end-point potentiometrically (2.2.20).
A. 1-chlorophthalazine,
1 mL of 1 M sodium hydroxide is equivalent to 36.46 mg of
HCl.
B. hydrazine, STORAGE
In a stoppered container made of glass or another inert
material, at a temperature not exceeding 30 °C.

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C. phthalazin-1(2H)-one,

HYDROCHLORIC ACID, DILUTE

Acidum hydrochloridum dilutum
D. phthalazine. DEFINITION
Content : 9.5 per cent m/m to 10.5 per cent m/m of HCl
(Mr 36.46).
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PREPARATION
To 726 g of water R add 274 g of concentrated hydrochloric
acid and mix.
IDENTIFICATION
HYDROCHLORIC ACID, A. It is strongly acid (2.2.4).
CONCENTRATED B. It gives reaction (a) of chlorides (2.3.1).
C. It complies with the limits of the assay.
Acidum hydrochloridum concentratum TESTS
HCl Mr 36.46 Appearance. It is clear (2.2.1) and colourless (2.2.2,
[7647-01-0] Method II).
Free chlorine : maximum 1 ppm.
DEFINITION
To 60 mL add 50 mL of carbon dioxide-free water R, 1 mL
Content : 35.0 per cent m/m to 39.0 per cent m/m. of a 100 g/L solution of potassium iodide R and 0.5 mL of
CHARACTERS iodide-free starch solution R. Allow to stand in the dark for
2 min. Any blue colour disappears on the addition of 0.2 mL
Appearance : clear, colourless, fuming liquid. of 0.01 M sodium thiosulfate.
Solubility : miscible with water.
Sulfates (2.4.13) : maximum 5 ppm.
Relative density : about 1.18.
To 26 mL add 10 mg of sodium hydrogen carbonate R and
IDENTIFICATION evaporate to dryness on a water-bath. Dissolve the residue
A. Dilute with water R. The solution is strongly acid (2.2.4). in 15 mL of distilled water R.
B. It gives reaction (a) of chlorides (2.3.1). Residue on evaporation : maximum 0.01 per cent.
C. It complies with the limits of the assay. Evaporate 100.0 g to dryness on a water-bath or using a rotary
evaporator and dry the residue at 100-105 °C. The residue
TESTS weighs a maximum of 10 mg.
Appearance of solution. To 2 mL add 8 mL of water R. The ASSAY
solution is clear (2.2.1) and colourless (2.2.2, Method II). To 6.00 g add 30 mL of water R. Titrate with 1 M sodium
Free chlorine : maximum 4 ppm. hydroxide, determining the end-point potentiometrically
To 15 mL add 100 mL of carbon dioxide-free water R, 1 mL (2.2.20).
of a 100 g/L solution of potassium iodide R and 0.5 mL of 1 mL of 1 M sodium hydroxide is equivalent to 36.46 mg of
iodide-free starch solution R. Allow to stand in the dark for HCl.

3018 See the information section on general monographs (cover pages)