Edition: BP 2025 (Ph. Eur. 11.6 update)
DEFINITION
Content
99.0 per cent to 101.0 per cent of 4-hydroxy-3-methoxybenzaldehyde (dried substance).
CHARACTERS
Appearance
White or slightly yellowish, crystalline powder or needles.
Solubility
Slightly soluble in water, freely soluble in ethanol (96 per cent) and in methanol. It dissolves in dilute solutions of alkali hydroxides.
IDENTIFICATION
First identification: B.
Second identification: A, C.
A. Melting point (2.2.14): 81 °C to 84 °C.
B. Infrared absorption spectrophotometry (2.2.24).
Comparison vanillin CRS.
C. To 5 mL of a saturated solution of the substance to be examined add 0.2 mL of ferric chloride solution R1. A blue colour is produced. Heat to 80 °C. The solution becomes brown. On cooling, a white precipitate is formed.
TESTS
Appearance of solution
Dissolve 1.0 g in ethanol (96 per cent) R and dilute to 20 mL with the same solvent. The solution is clear (2.2.1) and not more intensely coloured than reference solution B6 (2.2.2, Method II).
Related substances
Thin-layer chromatography (2.2.27).
Test solution (a) Dissolve 0.1 g of the substance to be examined in methanol R and dilute to 5 mL with the same solvent.
Test solution (b) Dilute 1 mL of test solution (a) to 10 mL with methanol R.
Reference solution (a) Dissolve 10 mg of vanillin CRS in methanol R and dilute to 5 mL with the same solvent.
Reference solution (b) Dilute 0.5 mL of test solution (a) to 100 mL with methanol R. Plate TLC silica gel F254 plate R.
Mobile phase anhydrous acetic acid R, methanol R, methylene chloride R (0.5:1:98.5 V/V/V). Application 5 µL.
Development In an unsaturated tank over 1/2 of the plate.
Drying In a current of cold air.
Detection A Examine in ultraviolet light at 254 nm.
Results A Any spot in the chromatogram obtained with test solution (a), apart from the principal spot, is not more intense than the spot in the chromatogram obtained with reference solution (b) (0.5 per cent).
Detection B Spray with dinitrophenylhydrazine-aceto-hydrochloric solution R and examine in daylight.
Results B Any spot in the chromatogram obtained with test solution (a), apart from the principal spot, is not more intense than the spot in the chromatogram obtained with reference solution (b) (0.5 per cent).
Reaction with sulfuric acid
Dissolve 50 mg in 5 mL of sulfuric acid R. After 5 min, the solution is not more intensely coloured than a mixture of 4.9 mL of yellow primary solution and 0.1 mL of red primary solution or a mixture of 4.9 mL of yellow primary solution and 0.1 mL of blue primary solution (2.2.2, Method I).
Loss on drying
(2.2.32): maximum 1.0 per cent, determined on 1.000 g by drying in a desiccator for 4 h.
Sulfated ash
(2.4.14): maximum 0.05 per cent, determined on 2.0 g.
ASSAY
Dissolve 0.120 g in 20 mL of ethanol (96 per cent) R and add 60 mL of carbon dioxide-free water R. Titrate with 0.1 M sodium hydroxide, determining the end-point potentiometrically (2.2.20).
1 mL of 0.1 M sodium hydroxide is equivalent to 15.21 mg of C8H8O3.
STORAGE
Store protected from light.
