Propyl Gallate BP Grade
Ph Eur --- C10H12O5 --- 212.2 --- 121-79-9
Action and use: Antioxidant.
DEFINITION
Propyl gallate contains not less than 97.0 per cent and not more than the equivalent
of 103.0 per cent of propyl 3,4,5-trihydroxybenzoate, calculated with reference to
the dried substance.
CHARACTERS
A white or almost white, crystalline powder, very slightly soluble in water, freely
soluble in ethanol (96 per cent). It dissolves in dilute solutions of alkali
hydroxides.
IDENTIFICATION
First identificationıB.
Second identificationıA, C, D.
A. Melting point: 148C to 151C.
B. Examine by infrared absorption spectrophotometry.
C. Examine the chromatograms obtained in the test for gallic acid.
D. Dissolve about 10 mg in 10 ml of water by heating to about 70C. Cool and add 1 ml
of bismuth subnitrate solution. A bright yellow precipitate is formed.
TESTS
Appearance of solution: Dissolve 1.0 g in ethanol (96 per cent) and
dilute to 20 ml with the same solvent. The solution is clear and not more intensely
coloured than reference solution.
Gallic acid: Examine by thin-layer chromatography.
Total chlorine: Mix 0.5 g with 2 g of calcium carbonate. Dry and ignite at
700 ± 50C. Take up the residue with 20 ml of dilute nitric acid and dilute to 30 ml
with water. 15 ml of the solution, without further addition of dilute nitric acid,
complies with the limit test for chlorides (200 ppm).
Chlorides: To 1.65 g add 50 ml of water. Shake for 5 min. Filter. 15 ml of
the filtrate complies with the limit test for chlorides (100 ppm).
Zinc: Not more than 25.0 ppm of Zn, determined by atomic absorption
spectrometry
Heavy metals: 2.0 g complies with limit test C for heavy metals (10 ppm).
Prepare the reference solution using 2 ml of lead standard solution (10 ppm Pb).
Loss on drying: Not more than 0.5 per cent, determined on 1.000 g by drying
in an oven at 105C.
Sulphated ash: Not more than 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 C10H12O5 taking the specific absorbance to be 503.
Propyl Gallate USP NFGrade
C10H12O5 --- 212.20 --- CAS 121-79-9.
Benzoic acid, 3,4,5-trihydroxy-, propyl ester.
Propyl Gallate contains not less than 98.0 percent and not more than 102.0 percent of C10H12O5, calculated on the dried basis.
Identification:
A: Infrared Absorption 197M .
B: Ultraviolet Absorption 197U
Solution: 10 3g per mL.
Medium: methanol.
Melting range: between 146 and 150 .
Loss on drying: Dry it at 105 for 4 hours: it loses not more than 0.5% of its
weight.
Residue on ignition: not more than 0.1%.
Heavy metals: 0.001%.
Assay: Transfer about 100 mg of Propyl Gallate, accurately weighed, to a
250-mL volumetric flask, dissolve in about 100 mL of methanol, dilute with methanol
to volume, and mix. Transfer 5.0 mL of this solution to a 200-mL volumetric flask,
dilute with methanol to volume, and mix. Concomitantly determine the absorbances of
this solution and a Standard solution of USP Propyl Gallate RS in methanol having a
known concentration of about 10 micro gm per mL, in 1-cm cells at the wavelength of
maximum absorbance at about 273 nm, with a suitable spectrophotometer, using
methanol as the blank. Calculate the quantity, in mg, of C10H12O5 in the portion of
Propyl Gallate taken by the formula:
10C(AU / AS)
in which C is the concentration, in microgm per mL, of USP Propyl Gallate in the
Standard solution, and AU and AS are the absorbances of the solution of Propyl
Gallate and the Standard solution, respectively.
Propyl Gallate FCC Food Grade
Gallic Acid, Propyl Ester
C10H12O5 Formula wt 212.20
INS: 310 CAS: [121-79-9]
DESCRIPTION
Propyl Gallate occurs as a fine, white to nearly white powder. It is
slightly soluble in water and freely soluble in alcohol and in ether.
Function: Antioxidant.
REQUIREMENTS
Identification: Place about 5 g of sample and several boiling chips into a
500-mL round-bottom flask, connect a water-cooled condenser to the flask, and
introduce a steady stream of nitrogen into the flask, maintaining the flow of
nitrogen at all times during the remainder of the procedure. Pour 100 mL of 1 N
sodium hydroxide through the top of the condenser, heat the solution to
boiling, boil for 30 min, and cool. Place the round-bottom flask in an ice bath, and
slowly, with occasional swirling, add dilute sulfuric acid (10%) until a pH of 2 to
3 is obtained (using pH paper). Filter the precipitate through a sintered-glass
crucible, wash with a minimum amount of water, and dry at 110C for 2 h. The gallic
acid so obtained melts at about 240C with decomposition.
Assay: Not less than 98.0% and not more than 102.0% of C10H12O5 after
drying.
Lead: Not more than 1 mg/kg.
Loss on Drying: Not more than 0.5%.
Melting Range: Between 146C and 150C.
Residue on Ignition: Not more than 0.1%.
