Dodecyl gallate, or lauryl gallate, is the ester of dodecanol and gallic acid. As a food additive it is used under the E number E312 as an antioxidant and preservative.
DEFINITION
Dodecyl 3,4,5-trihydroxybenzoate.
Content: 97.0 per cent to 103.0 per cent (dried substance).
CHARACTERS
Appearance: White or almost white, crystalline powder.
Solubility: Very slightly soluble or practically insoluble in water, freely soluble in ethanol (96 per cent), slightly soluble in methylene chloride.
IDENTIFICATION
A. Determine the melting point of the substance to be examined. Mix equal parts of the substance to be examined and dodecyl gallate CRS and determine the melting point of the mixture. The difference between the melting points (which are about 96C) is not greater than 2C.
B. Examine the chromatograms obtained in the test for impurity A.
Results The principal spot in the chromatogram obtained with test solution (b) is similar in position, colour and size to the principal spot in the chromatogram obtained with reference solution (a).
TESTS
Impurity A
Thin-layer chromatography: impurity A: any spot due to impurity A is not more intense than the spot in the chromatogram obtained with reference solution (c) (0.5 per cent). Impurity A=3,4,5-trihydroxybenzoic acid (gallic acid).
Chlorides: Maximum 100 ppm.
Loss on drying: Maximum 0.5 per cent, determined on 1.000 g by drying in an oven at 70C.
Sulfated ash: Maximum 0.1 per cent, determined on 1.0 g.
ASSAY
Dissolve 0.100 g in methanol and dilute to 250.0 mL with the same solvent. Dilute 5.0 mL of the solution to 200.0 mL with methanol.
Measure the absorbance at the absorption maximum at 275 nm.
Calculate the content of C19H30O5 taking the specific absorbance to be 321.
