Oxybenzone
» Oxybenzone contains not less than 97.0 percent and not more than 103.0 percent of C14H12O3, calculated on the dried basis.
Packaging and storage
Preserve in tight, light-resistant containers.
USP Reference standards 11
USP Oxybenzone RS.
Identification
Solution:
10 µg per mL.
Medium:
methanol.
Absorptivities at 287 nm, calculated on the dried basis, do not differ by more than 3.0%.
Congealing temperature 651:
not lower than 62.0.
Loss on drying 731
Dry it in vacuum at 40 for 2 hours: it loses not more than 2.0% of its weight.
Assay
Standard preparation
Dissolve an accurately weighed quantity of USP Oxybenzone RS in methanol, and quantitatively dilute with methanol, if necessary, to obtain a solution having a known concentration of about 10 µg per mL.
Assay preparation
Dissolve about 100 mg of Oxybenzone, accurately weighed, in methanol in a 100-mL volumetric flask, dilute with methanol to volume, and mix. Agitate gently, if necessary, to hasten solution. Pipet 1 mL of the solution so obtained into a second 100-mL volumetric flask, dilute with methanol to volume, and mix.
Procedure
Concomitantly determine the absorbances of the Assay preparation and the Standard preparation in 1-cm cells at the wavelength of maximum absorbance at about 287 nm, with a suitable spectrophotometer, using methanol as the blank. Calculate the quantity, in mg, of C14H12O3 in the portion of Oxybenzone taken by the formula:
10C(AU / AS)
in which C is the concentration, in µg per mL, of USP Oxybenzone RS in the Standard preparation; and AU and AS are the absorbances of the Assay preparation and the Standard preparation, respectively.
Auxiliary Information
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Chromatographic Column
USP32NF27 Page 3160
Pharmacopeial Forum: Volume No. 27(3) Page 2572
Chromatographic columns text is not derived from, and not part of, USP 32 or NF 27.
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