Padimate O
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C17H27NO2 277.40

Benzoic acid, 4-(dimethylamino)-, 2-ethylhexyl ester.
2-Ethylhexyl p-(dimethylamino)benzoate [21245-02-3].
» Padimate O contains not less than 97.0 percent and not more than 103.8 percent of C17H27NO2.
Packaging and storage— Preserve in tight, light-resistant containers.
Solution: 5 µg per mL.
Medium: alcohol.
Absorptivities at 312 nm do not differ by more than 4.0%.
Specific gravity 841: between 0.990 and 1.000.
Refractive index 831: between 1.5390 and 1.5430.
Acid value 401: not more than 1.0.
Saponification value 401: between 195 and 215, reflux temperature being maintained for 4 hours.
Chromatographic purity—
Chromatographic system (see Chromatography 621)—The gas chromatograph is equipped with a flame-ionization detector and a 3-mm × 1.8-m stainless steel column packed with 10 percent liquid phase G9 on support S1A. The column temperature is programmed at a rate of 10 per minute from 150 to 250, then maintained at 250 for 10 minutes, and helium is used as the carrier gas.
Procedure— Chromatograph 2 µL of a 1 in 100 solution of Padimate O in chloroform: the response due to padimate O is not less than 98.0% of the sum of the responses on the chromatogram, exclusive of the chloroform peak.
Assay— Dissolve about 500 mg of Padimate O, accurately weighed, in 75 mL of acetic anhydride, and titrate with 0.1 N perchloric acid VS, determining the endpoint potentiometrically. Each mL of 0.1 N perchloric acid is equivalent to 27.74 mg of C17H27NO2.
Auxiliary Information— Please check for your question in the FAQs before contacting USP.
Topic/Question Contact Expert Committee
Monograph Feiwen Mao, M.S.
(MDOOD05) Monograph Development-Ophthalmics Oncologics and Dermatologicals
Reference Standards Lili Wang, Technical Services Scientist
USP32–NF27 Page 3190
Chromatographic Column—
Chromatographic columns text is not derived from, and not part of, USP 32 or NF 27.