Propyl Gallate
(proe' pil gal' ate).
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C10H12O5 212.20
Benzoic acid, 3,4,5-trihydroxy-, propyl ester;    
Propyl gallate     [121-79-9].
Propyl Gallate contains NLT 98.0% and NMT 102.0% of propyl gallate (C10H12O5), calculated on the dried basis.
•  B. Ultraviolet Absorption 197U
Sample solution:  10 µg/mL in methanol
Acceptance criteria:  Meets the requirements
•  Procedure
Standard solution:  10 µg/mL of USP Propyl Gallate RS in methanol
Sample solution:  10 µg/mL of Propyl Gallate in methanol
Blank:  Methanol
Instrumental conditions 
Mode:  UV
Analytical wavelength:  Maximum at about 273 nm
Cell:  1 cm
Samples:  Standard solution and Sample solution
Calculate the percentage of propyl gallate (C10H12O5) in the portion of the sample taken:
Result = (AU/AS) × (CS/CU) × 100
AU== absorbance of the Sample solution
AS== absorbance of the Standard solution
CS== concentration of USP Propyl Gallate RS in the Standard solution (µg/mL)
CU== concentration of the Sample solution (µg/mL)
Acceptance criteria:  98.0%–102.0% on the dried basis
•  Residue on Ignition 281: NMT 0.1%
•  Heavy Metals, Method II 231: NMT 10 ppm
•  Loss on Drying 731: Dry a sample at 105 for 4 h: it loses NMT 0.5% of its weight.
•  Packaging and Storage: Preserve in tight containers, protected from light, and avoid contact with metals.
•  USP Reference Standards 11
USP Propyl Gallate RS
Auxiliary Information— Please check for your question in the FAQs before contacting USP.
Topic/Question Contact Expert Committee
Monograph Robert H. Lafaver, M.S.
Scientific Liaison
(EXC2010) Monographs - Excipients
Reference Standards RS Technical Services
USP35–NF30 Page 1931