Trioxsalen Tablets »Trioxsalen Tablets contain not less than 93.0percent and not more than 107.0percent of the labeled amount of C14H12O3. Packaging and storage— Preserve in well-closed,light-resistant containers. USP Reference standards á11ñ USP Trioxsalen RS. Identification— Triturate an amount of finely powdered Tablets,equivalent to about 10mg of trioxsalen,with 100mLof chloroform,and filter.Apply 5µLeach of this solution and a Standard solution of USP Trioxsalen RSin chloroform having a known concentration of 100µg per mLto a suitable thin-layer chromatographic plate (see Chromatography á621ñ)coated with a 0.25-mm layer of chromatographic silica gel.Allow the spots to dry,and develop the chromatogram,using methanol as the solvent,until the solvent front has moved about three-fourths of the length of the plate.Remove the plate from the developing chamber,mark the solvent front,and allow the solvent to evaporate.Locate the spots on the plate by viewing under an UVlamp:the RFvalue of the principal spot obtained from the test solution corresponds to that obtained from the Standard solution. Dissolution á711ñ Apparatus 2: 100rpm. Time: 60minutes. Dilute simulated intestinal fluid— Prepare a 1in 12solution of simulated intestinal fluid TSand water. Procedure— Assemble the apparatus,adding 225mLof Dilute simulated intestinal fluidto each vessel,and operate the apparatus for 40minutes.At the end of the 40minutes,immediately add 675mLof dehydrated alcohol to each of the vessels.Continue to operate the apparatus for an additional 20minutes.Determine the amount of C14H12O3dissolved from UVabsorbance determined at the wavelength of maximum absorbance at about 252nm,filtered portions of the solution under test,in comparison with a Standard solution having a known concentration of USP Trioxsalen RSin the same medium. Tolerances— Not less than 75%(Q)of the labeled amount of C14H12O3is dissolved in 60minutes. Uniformity of dosage units á905ñ: meet the requirements. Assay— Weigh and finely powder not less than 20Tablets.Transfer an accurately weighed portion of the powder,equivalent to about 5mg of trioxsalen,to a separator containing 25mLof water.Extract with three 25-mLportions of chloroform,filtering each extract into a 100-mLvolumetric flask.Wash the filter with chloroform,dilute with chloroform to volume,and mix.Transfer 10.0mLof this solution to a second 100-mLvolumetric flask,dilute with chloroform to volume,and mix.Concomitantly determine the absorbances of this solution and a solution of USP Trioxsalen RSin the same medium having a known concentration of about 5µg per mLin 1-cm cells at the wavelength of maximum absorbance at about 252nm,with a suitable spectrophotometer,using chloroform as the blank.Calculate the quantity,in mg,of C14H12O3in the portion of Tablets taken by the formula: C(AU/AS), in which Cis the concentration,in µg per mL,of USP Trioxsalen RSin the Standard solution,and AUand ASare the absorbances of the solution from the Tablets and the Standard solution,respectively. Auxiliary Information— Staff Liaison:Lawrence Evans,III,Ph.D.,Scientist Expert Committee:(PA6)Pharmaceutical Analysis 6 USP28–NF23Page 1989 Phone Number:1-301-816-8389