(dye eth'' il tol ue' a mide).
» Diethyltoluamide contains not less than 95.0 percent and not more than 103.0 percent of the meta-isomer of C12H17NO, calculated on the anhydrous basis.
Packaging and storage Preserve in tight containers.
USP Reference standards 11
Identification, Infrared Absorption 197S: solution; Assay preparation versus Standard preparation in Assay, in spectral region between 8 µm and 15 µm.
Specific gravity 841: between 0.996 and 1.002.
Refractive index 831: between 1.520 and 1.524.
Acidity Dissolve 10.0 g in 50 mL of neutralized alcohol, add phenolphthalein TS, and titrate with 0.010 N sodium hydroxide: not more than 4.0 mL of 0.010 N sodium hydroxide is required.
Water, Method I 921: not more than 0.5%.
Assay Transfer about 200 mg of Diethyltoluamide, accurately weighed, to a 10-mL volumetric flask, dilute with carbon disulfide to volume, and mix to obtain the Assay preparation. Concomitantly determine the absorbances of the Assay preparation and of a Standard preparation of USP Diethyltoluamide RS in carbon disulfide having a known concentration of about 20 mg per mL in 1-mm cells at the wavelength of maximum absorbance at about 14.1 µm and at the wavelength of minimum absorbance at about 14.4 µm, with a suitable IR spectrophotometer, using carbon disulfide as the blank. Calculate the quantity, in mg, of the meta-isomer of C12H17NO in the Diethyltoluamide taken by the formula:
10C(AU14.1 AU14.4) / (AS14.1 AS14.4)in which C is the concentration, in mg per mL, of USP Diethyltoluamide RS in the Standard preparation, and AU and AS are the absorbances of the Assay preparation and the Standard preparation, respectively, at the wavelengths indicated by the subscripts.
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USP35NF30 Page 2897