Padimate O
;)
Benzoic acid,4-(dimethylamino)-,2-ethylhexyl ester.
2-Ethylhexyl p-(dimethylamino)benzoate [21245-02-3].
»Padimate Ocontains not less than 97.0percent and not more than 103.8percent of C17H27NO2.
Packaging and storage—
Preserve in tight,light-resistant containers.
Identification—
A:
Infrared Absorption á197Fñ.
Solution:
5µg per mL.
Medium:
alcohol.
Absorptivities at 312nm do not differ by more than 4.0%.
Specific gravity á841ñ:
between 0.990and 1.000.
Refractive index á831ñ:
between 1.5390and 1.5430.
Acid value á401ñ:
not more than 1.0.
Saponification value á401ñ:
between 195and 215,reflux temperature being maintained for 4hours.
Chromatographic purity—
Chromatographic system
(see Chromatography á621ñ)—The gas chromatograph is equipped with a flame-ionization detector and a 3-mm ×1.8-m stainless steel column packed with 10percent liquid phase G9on support S1A.The column temperature is programmed at a rate of 10
per minute from 150to 250,then maintained at 250for 10minutes,and helium is used as the carrier gas.
per minute from 150to 250,then maintained at 250for 10minutes,and helium is used as the carrier gas.
Procedure—
Chromatograph 2µLof a 1in 100solution of Padimate Oin chloroform:the response due to padimate Ois not less than 98.0%of the sum of the responses on the chromatogram,exclusive of the chloroform peak.
Assay—
Dissolve about 500mg of Padimate O,accurately weighed,in 75mLof acetic anhydride,and titrate with 0.1Nperchloric acid VS,determining the endpoint potentiometrically.Each mLof 0.1Nperchloric acid is equivalent to 27.74mg of C17H27NO2.
Auxiliary Information—
Staff Liaison:Lawrence Evans,III,Ph.D.,Scientist
Expert Committee:(PA6)Pharmaceutical Analysis 6
USP28–NF23Page 1458
Phone Number:1-301-816-8389