(trye ox' sa len).
» Trioxsalen contains not less than 97.0 percent and not more than 103.0 percent of C14H12O3, calculated on the dried basis.
[CautionAvoid exposing the skin to Trioxsalen. ]
Packaging and storage Preserve in well-closed, light-resistant containers.
USP Reference standards 11
B: Ultraviolet Absorption 197U
Solution: 5 µg per mL.
C: The retention time of the major peak in the chromatogram of the Assay preparation corresponds to that of the Standard preparation as obtained in the Assay.
Loss on drying 731 Dry it at 105 for 6 hours: it loses not more than 0.5% of its weight.
Residue on ignition 281: not more than 0.5%.
Related compounds In the chromatogram obtained from the Assay preparation in the Assay, the sum of the responses of any peaks detected, other than the major peak due to trioxsalen, is not more than 2.0% of the total of all the peak responses and the response of the peak occurring at retention time relative to trioxsalen of about 0.75 is not more than 1.5% of the total of all responses.
Mobile phase Prepare a filtered and degassed mixture of methanol and water (70:30). Make adjustments if necessary (see System Suitability under Chromatography 621).
Standard preparation Dissolve an accurately weighed quantity of USP Trioxsalen RS in tetrahydrofuran to obtain a solution having a known concentration of about 1 mg per mL. Transfer 5.0 mL of this solution to a 100-mL volumetric flask, dilute with Mobile phase to volume, and mix.
Assay preparation Transfer about 100 mg of Trioxsalen, accurately weighed, to a 100-mL volumetric flask, dissolve in tetrahydrofuran, dilute with tetrahydrofuran to volume, mix, and filter. Transfer 5.0 mL of this solution to a 100-mL volumetric flask, dilute with Mobile phase to volume, and mix.
Chromatographic system (see Chromatography 621)The liquid chromatograph is equipped with a 254-nm detector and a 4.6-mm × 25-cm column that contains packing L1. The flow rate is about 1 mL per minute. Chromatograph the Standard preparation, and record the peak responses as directed for Procedure: the tailing factor for the trioxsalen peak is not more than 2.0, and the relative standard deviation for replicate injections is not more than 2.0%.
Procedure Separately inject equal volumes (about 20 µL) of the Standard preparation and the Assay preparation into the chromatograph, record the chromatograms, and measure the responses for the major peaks. Calculate the quantity, in mg, of C14H12O3 in the portion of Trioxsalen taken by the formula:
2000C(rU / rS)in which C is the concentration, in mg per mL, of USP Trioxsalen RS in the Standard preparation, and rU and rS are the peak responses obtained from the Assay preparation and the Standard preparation, respectively.
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USP35NF30 Page 4957