Benzocaine
EUROPEAN PHARMACOPOEIA 5.0
Appearance of solution. Solution S is clear (2.2.1) and
not more intensely coloured than reference solution Y6
(2.2.2, Method II).
Acidity or alkalinity. To 25 ml of solution S add 0.1 ml of
phenolphthalein solution R. The solution is colourless. Add
0.3 ml of 0.01 M sodium hydroxide. The solution is pink.
Add 0.1 ml of methyl red solution R and 0.5 ml of 0.01 M
hydrochloric acid. The solution is orange-red.
Volatile bases and salts of volatile bases (2.4.1). 0.20 g
complies with limit test B for ammonium (50 ppm). Prepare
the standard using 0.1 ml of ammonium standard solution
(100 ppm NH4) R. Replace heavy magnesium oxide by 2.0 ml
of strong sodium hydroxide solution R.
Loss on drying (2.2.32). Not more than 5.0 per cent,
determined on 1.000 g by drying in an oven at 100 °C to
105 °C for 4 h.
Sulphated ash (2.4.14). Not more than 0.1 per cent,
determined on 1.0 g.
Second identification : A, C, D.
A. Melting point (2.2.14) : 89 °C to 92 °C.
B. Examine by infrared absorption spectrophotometry
(2.2.24), comparing with the spectrum obtained with
benzocaine CRS.
C. To about 50 mg in a test-tube add 0.2 ml of a 500 g/l
solution of chromium trioxide R. Cover the mouth of the
tube with a piece of filter paper moistened with a freshly
prepared mixture of equal volumes of a 50 g/l solution
of sodium nitroprusside R and a 200 g/l solution of
piperazine hydrate R. Boil gently for at least 30 s. A blue
colour develops on the filter paper.
D. Dissolve about 50 mg in alcohol R and dilute to 100 ml
with the same solvent. 2 ml of the solution gives the
reaction of primary aromatic amines (2.3.1).
STORAGE
Store protected from light.
STORAGE
Store protected from light.
TESTS
Appearance of solution. Dissolve 1.0 g in alcohol R and
dilute to 20 ml with the same solvent. The solution is clear
(2.2.1) and colourless (2.2.2, Method II).
ASSAY
Dissolve 2.000 g in water R and dilute to 100.0 ml with
Acidity or alkalinity. Dissolve 0.5 g in 10 ml of alcohol R
the same solvent. Transfer 25.0 ml of the solution to a
previously neutralised to 0.05 ml of phenolphthalein
separating funnel, add 10 ml of a 4 g/l solution of sodium
solution R. Add 10 ml of carbon dioxide-free water R. The
hydroxide R, 10.0 ml of a freshly prepared 50 g/l solution
solution remains colourless and not more than 0.5 ml of
of potassium iodide R and 25 ml of methylene chloride R.
0.01 M sodium hydroxide is required to change the colour
Shake vigorously, allow to separate and discard the lower
of the indicator.
layer. Shake the upper layer with three quantities, each of
Loss on drying (2.2.32). Not more than 0.5 per cent,
10 ml, of methylene chloride R and discard the lower layers. determined on 1.00 g by drying in vacuo.
To the upper layer add 40 ml of hydrochloric acid R, allow to
cool and titrate with 0.05 M potassium iodate until the deep Sulphated ash (2.4.14). Not more than 0.1 per cent,
determined on 1.0 g.
brown colour is almost discharged. Add 4 ml of methylene
chloride R and continue the titration, shaking vigorously,
ASSAY
until the lower layer is no longer brown. Carry out a blank
Dissolve 0.400 g in a mixture of 25 ml of hydrochloric
titration using a mixture of 10.0 ml of a freshly prepared
50 g/l solution of potassium iodide R, 20 ml of water R and acid R and 50 ml of water R. Carry out the determination of
primary aromatic amino-nitrogen (2.5.8).
40 ml of hydrochloric acid R.
1 ml of 0.1 M sodium nitrite is equivalent to 16.52 mg
1 ml of 0.05 M potassium iodate is equivalent to 44.81 mg
of C9H11NO2.
of C27H42ClNO2.
01/2005:0011
01/2005:0066
BENZOCAINE
BENZOIC ACID
Benzocainum
C9H11NO2
Acidum benzoicum
Mr 165.2
DEFINITION
Benzocaine contains not less than 99.0 per cent and
not more than the equivalent of 101.0 per cent of ethyl
4-aminobenzoate, calculated with reference to the dried
substance.
C7 H 6 O 2
Mr 122.1
DEFINITION
Benzoic acid contains not less than 99.0 per cent and
not more than the equivalent of 100.5 per cent of
benzenecarboxylic acid.
CHARACTERS
A white, crystalline powder or colourless crystals, very
slightly soluble in water, freely soluble in alcohol.
CHARACTERS
A white, crystalline powder or colourless crystals, odourless
or with a very slight characteristic odour, slightly soluble
in water, soluble in boiling water, freely soluble in alcohol
and in fatty oils.
IDENTIFICATION
First identification : A, B.
IDENTIFICATION
A. Melting point (2.2.14) : 121 °C to 124 °C.
1072
See the information section on general monographs (cover pages)