Dioxybenzone
;)
Methanone,(2-hydroxy-4-methoxyphenyl)(2-hydroxyphenyl)-.
2,2¢-Dihydroxy-4-methoxybenzophenone [131-53-3].
»Dioxybenzone contains not less than 97.0percent and not more than 103.0percent of C14H12O4,calculated on the dried basis.
Packaging and storage—
Preserve in tight,light-resistant containers.
Identification—
A:
Infrared Absorption á197Kñ.
B:
Ultraviolet Absorption á197Uñ—
Solution:
10µg per mL.
Medium:
methanol.
Absorptivities at 286nm,calculated on the dried basis,do not differ by more than 3.0%.
Congealing temperature á651ñ:
not lower than 68.0
.
.
Loss on drying á731ñ—
Dry it in vacuum at 40for 2hours:it loses not more than 2.0%of its weight.
for 2hours:it loses not more than 2.0%of its weight.
Assay—
Dissolve about 100mg of Dioxybenzone,accurately weighed,in toluene in a 100-mLvolumetric flask,dilute with toluene to volume,and mix.Pipet 1mLof this solution into a second 100-mLvolumetric flask,add methanol to volume,and mix.Similarly,prepare a Standard solution of USP Dioxybenzone RS,accurately weighed,having a known concentration of about 10µg per mL.Concomitantly determine the absorbances of both solutions in 1-cm cells at the wavelength of maximum absorbance at about 325nm,with a suitable spectrophotometer,using a 1in 100solution of toluene in methanol as the blank.Calculate the quantity,in mg,of C14H12O4in the Dioxybenzone taken by the formula:
10C(AU/AS),
in which Cis the concentration,in µg per mL,of USP Dioxybenzone RSin the Standard solution,and AUand ASare the absorbances of the solution of Dioxybenzone and the Standard solution,respectively.
Auxiliary Information—
Staff Liaison:Lawrence Evans,III,Ph.D.,Scientist
Expert Committee:(PA6)Pharmaceutical Analysis 6
USP28–NF23Page 666
Phone Number:1-301-816-8389