Avobenzone
;)
1,3-Propanedione,1-[4-(1,1-dimethylethyl)phenyl]-3-(4-methoxyphenyl)-.
1-(p-tert-Butylphenyl)-3-(p-methoxyphenyl)-1,3-propanedione [70356-09-1].
»Avobenzone contains not less than 95.0percent and not more than 105.0percent of C20H22O3,calculated on the dried basis.
Packaging and storage—
Preserve in tight,light-resistant containers.
Identification—
A:
Infrared Absorption á197Kñ.
B:
Ultraviolet Absorption á197Uñ—
Solution:
5µg per mL.
Medium:
alcohol.
Absorptivities at 360nm do not differ by more than 3.0%.
Loss on drying á731ñ—
Dry it in vacuum at 70
for 4hours:it loses not more than 0.5%of its weight.
for 4hours:it loses not more than 0.5%of its weight.
Chromatographic purity—
Procedure—
Inject a volume (about 1µL)of Test solutioninto the chromatograph,record the chromatogram,and measure the peak responses.Calculate the percentage of each impurity in the portion of Avobenzone taken by the formula:
100(rI/rS),
in which rIis the response of each individual peak,other than the avobenzone peak,in the chromatogram of the Test solution;and rSis the sum of the responses of all of the peaks in the chromatogram of the Test solution:not more than 3.0%of any individual impurity is found,and the sum of all of the impurities is not more than 4.5%.
Assay—
Standard preparation—
Dilute an accurately measured quantity of USP Avobenzone RSin acetone,and dilute quantitatively,and stepwise if necessary,with acetone to obtain a solution having a known concentration of about 50mg per mL.
Assay preparation—
Transfer about 500mg of Avobenzone,accurately weighed,to a 10-mLvolumetric flask,dilute with acetone to volume,and mix.
Chromatographic system
(see Chromatography á621ñ)—The gas chromatograph is equipped with a flame-ionization detector and a 0.32-mm ×25-m fused silica capillary column coated with phase G1.The column temperature is maintained at about 200until the time of injection,then increased at a rate of 4per minute to 280.The injector port is maintained at 200,and the detector is maintained at about 280.Helium is used as the carrier gas.
until the time of injection,then increased at a rate of 4per minute to 280.The injector port is maintained at 200,and the detector is maintained at about 280.Helium is used as the carrier gas.
Procedure—
Separately inject equal volumes (about 1µL)of the Standard preparationand the Assay preparationinto the chromatograph,record the chromatograms,and measure the responses for the major peaks.Calculate the quantity,in mg,of C20H22O3in the portion of Avobenzone taken by the formula:
10C(rU/rS),
in which Cis the concentration,in mg per mL,of USP Avobenzone RSin the Standard preparation;and rUand rSare the peak responses obtained from the Assay preparationand the Standard preparation,respectively.
Auxiliary Information—
Staff Liaison:Lawrence Evans,III,Ph.D.,Scientist
Expert Committee:(PA6)Pharmaceutical Analysis 6
USP28–NF23Page 204
Pharmacopeial Forum:Volume No.30(4)Page 1164
Phone Number:1-301-816-8389