(pad' i mate).
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.
USP Reference standards 11
Solution: 5 µg per mL.
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 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.
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USP35NF30 Page 4198