A: The retention time of the major peak (other than that due to the internal standard) in the chromatogram of the Assay preparation corresponds to that of the Standard preparation, as obtained in the Assay.

B: [NOTE—Since the visualizing agent used in this test is specific for phenols, solution preparations containing diphenyl phthalate and/or sesame oil may be used without interference.]

Visualizing agent— Transfer about 100 mg of Fast Blue B salt to a suitable flask containing about 100 mL of methanol, stir for about 5 minutes, and allow to settle. Decant the clear liquid into the sprayer reservoir. [NOTE—Prepare fresh daily.]

Identification preparation— Use the Standard preparation prepared as directed in the Assay.

Test preparation— Use the Assay preparation prepared as directed in the Assay.

Procedure— Apply separately 10 µL each of the Identification preparation and the Test preparation to a suitable thin-layer chromatographic plate (see Chromatography 621) coated with a 0.25-mm layer of chromatographic silica gel. Allow the spots to dry, and develop the plate in a chromatographic chamber that has been equilibrated (for about 2 minutes) with vapors from a solvent mixture of n-hexane and methylene chloride (1:1) until the solvent front has moved about 10 cm. Remove the plate from the developing chamber, quickly mark the solvent front, and allow the plate to dry at room temperature for about 5 minutes. Spray the plate with the Visualizing agent until it is uniformly damp (not saturated). Heat the plate at about 80 until the spots are developed: the color and RF value of the spot from the Test preparation correspond to those obtained from the Identification preparation.

Mobile phase , System suitability solution, Standard preparation, and Chromatographic system—Proceed as directed in the Assay.

D8-Tetrahydrocannabinol solution— Dilute an accurately measured volume of USP D8-Tetrahydrocannabinol RS quantitatively, and stepwise if necessary, with dehydrated alcohol to obtain a solution having a known concentration of about 4 µg per mL.

Test solution— Use the Assay preparation.

Procedure— Separately inject equal volumes (about 20 µL) of the D8-Tetrahydrocannabinol solution and the Test solution into the chromatograph, record the chromatograms, and measure the responses for all of the peaks. Calculate the percentage of D8-tetrahydrocannabinol in the portion of Dronabinol taken by the formula: in which C is the concentration, in mg per mL, of USP D8-Tetrahydrocannabinol RS in the D8-Tetrahydrocannabinol solution; W is the weight, in mg, of dronabinol in the portion of Dronabinol taken to prepare the Test solution; and rU and rS are the D8-tetrahydrocannabinol peak responses obtained from the Test solution and the D8-Tetrahydrocannabinol solution, respectively: not more than 2.0% is found.

(Official January 1, 2007)

Mobile phase— Prepare a filtered and degassed mixture of methanol, water, and tetrahydrofuran (71:24:5), making adjustments, if necessary (see System Suitability under Chromatography 621).

System suitability solution— Mix accurately measured volumes of USP D9-Tetrahydrocannabinol RS and USP D8-Tetrahydrocannabinol RS in dehydrated alcohol to obtain a solution having a known concentration of about 0.5 mg per mL of each component.

Standard preparation— Dissolve an accurately measured volume of USP D9-Tetrahydrocannabinol RS in dehydrated alcohol to obtain a solution having a known concentration of about 0.2 mg per mL.

Assay preparation— Transfer about 20 mg of Dronabinol, accurately weighed, to a 100-mL volumetric flask, dissolve in dehydrated alcohol, dilute with dehydrated alcohol to volume, and mix.

Chromatographic system (see Chromatography 621)—The liquid chromatograph is equipped with a 228-nm detector, a 4.6- × 30-mm guard column that contains 5-µm packing L1, and a 4.6-mm × 15-cm analytical column that contains 3-µm packing L1. The flow rate is about 1 mL per minute. Chromatograph the System suitability solution, and record the peak responses as directed for Procedure: the relative retention times are about 1.0 for D9-tetrahydrocannabinol and 1.14 for D8-tetrahydrocannabinol; the resolution, R, between dronabinol and D8-tetrahydrocannabinol is not less than 2.0; and the tailing factor of the D9-tetrahydrocannabinol peak is not more than 2.0. Chromatograph the Standard preparation, and record the peak responses as directed for Procedure: the relative standard deviation for replicate injections is not greater 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 all of the peaks. Calculate the quantity, in mg, of C21H30O2 in the portion of Dronabinol taken by the formula: in which C is the concentration, in mg per mL, of USP D9-Tetrahydrocannabinol RS in the Standard preparation; and rU and rS are the dronabinol peak responses obtained from the Assay preparation and the Standard preparation, respectively.