(kap say' i sin).
» Capsaicin contains not less than 90.0 percent and not more than 110.0 percent of the labeled percentage of total capsaicinoids. The content of capsaicin (C18H27NO3) is not less than 55 percent, and the sum of the contents of capsaicin and dihydrocapsaicin (C18H29NO3) is not less than 75 percent, and the content of other capsaicinoids is not more than 15 percent, all calculated on the dried basis.
[CautionHandle Capsaicin with care. Prevent inhalation of particles of it and prevent its contact with any part of the body. ]
Packaging and storage Preserve in tight containers, protected from light, and store in a cool place.
Labeling Label it to state the percentage content of total capsaicinoids.
USP Reference standards 11
USP Dihydrocapsaicin RS
Identification Prepare a test solution of Capsaicin in methanol containing 1 mg per mL. Prepare a Standard solution of USP Capsaicin RS in methanol containing 1 mg per mL. Separately apply 10-µL portions of the test solution and the Standard solution to a thin-layer chromatographic plate (see Chromatography 621) coated with a 0.25-mm layer of chromatographic silica gel mixture. Develop the chromatograms in a solvent system consisting of a mixture of ether and methanol (19:1) until the solvent front has moved about three-fourths of the length of the plate. Remove the plate from the chamber, and allow it to air-dry. Spray the plate with a 0.5% solution of 2,6-dibromoquinone-chlorimide in methanol, allow to stand in a chamber containing ammonia fumes, and examine the chromatograms: the blue color and the RF value of the principal spot obtained from the test solution correspond to those properties of the principal spot obtained from the Standard solution.
Melting range 741: between 57 and 66, but the range between beginning and end of melting does not exceed 5.
Loss on drying 731: Dry it in vacuum over phosphorus pentoxide at 40 for 5 hours: it loses not more than 1.0% of its weight.
Residue on ignition 281: not more than 1.0%.
Content of capsaicin, dihydrocapsaicin, and other capsaicinoids
Mobile phase Prepare a mixture of diluted phosphoric acid (1 in 1000) and acetonitrile (600:400). Pass through a filter having a porosity of 0.5 µm or finer, and degas. Make adjustments if necessary (see System Suitability under Chromatography 621).
Standard capsaicin solution Quantitatively dissolve an accurately weighed quantity of USP Capsaicin RS in methanol to obtain a solution having a known concentration of about 0.1 mg per mL.
Standard dihydrocapsaicin solution Quantitatively dissolve an accurately weighed quantity of USP Dihydrocapsaicin RS in methanol to obtain a solution having a known concentration of about 0.025 mg per mL.
Test solution Transfer about 25 mg of Capsaicin, accurately weighed, to a 250-mL volumetric flask, dilute with methanol to volume, and mix.
Chromatographic system (see Chromatography 621)The liquid chromatograph is equipped with a 281-nm detector and a 4.6-mm × 25-cm column that contains 5-µm packing L11 and is maintained at a constant temperature of about 30. Adjust the flow rate to obtain a retention time of about 20 minutes for the main capsaicin peak. Chromatograph the Standard capsaicin solution, and record the peak responses as directed for Procedure: the relative standard deviation for replicate injections is not more than 2%.
Procedure Separately inject equal volumes (about 20 µL) of the Standard capsaicin solution, the Standard dihydrocapsaicin solution, and the Test solution into the chromatograph, record the chromatogram for a period of time that is twice that of the retention time of capsaicin, and measure the areas of the responses for all of the peaks. Calculate the percentage of capsaicin (C18H27NO3) in the portion of Capsaicin taken by the formula:
25,000(C / W)(rU / rS)in which C is the concentration, in mg per mL, of USP Capsaicin RS in the Standard capsaicin solution; W is the weight, in mg, of Capsaicin taken to prepare the Test solution; and rU and rS are the capsaicin peak responses obtained from the Test solution and the Standard capsaicin solution, respectively. Not less than 55% is found. Calculate the percentage of dihydrocapsaicin (C18H29NO3) in the portion of Capsaicin taken by the formula:
25,000(C / W)(rU / rS)in which C is the concentration, in mg per mL, of USP Dihydrocapsaicin RS in the Standard dihydrocapsaicin solution; W is the weight, in mg, of Capsaicin taken to prepare the Test solution; and rU and rS are the dihydrocapsaicin peak responses obtained from the Test solution and the Standard dihydrocapsaicin solution, respectively. The sum of the percentage of capsaicin found and of the percentage of dihydrocapsaicin found is not less than 75%. Using the chromatograms obtained from the Standard capsaicin solution and the Test solution, calculate the percentage of other capsaicinoids in the portion of Capsaicin taken by the formula:
25,000(C / W)(rT / rS)in which C is the concentration, in mg per mL, of USP Capsaicin RS in the Standard capsaicin solution; W is the weight, in mg, of Capsaicin taken to prepare the Test solution; rT is the sum of the peak responses of the capsaicinoids other than capsaicin and dihydrocapsaicin in the chromatogram obtained from the Test solution; and rS is the capsaicin peak response obtained from the Standard capsaicin solution. Not more than 15% of other capsaicinoids is found.
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