A: Thin-Layer Chromatographic Identification Test 201—

B: The retention time of the major peak in the chromatogram of the Assay preparation corresponds to that in the chromatogram of the Standard preparation, as obtained in the Assay.

Mobile phase— Proceed as directed in the test for Limit of ondansetron related compound D under Ondansetron Hydrochloride.

System suitability solution— Dissolve suitable quantities of USP Ondansetron Related Compound D RS and USP Ondansetron Related Compound C RS in Mobile phase; and dilute quantitatively, and stepwise if necessary, with Mobile phase to obtain a solution containing about 0.5 µg per mL and 2 µg per mL, respectively.

Standard solution— Dissolve an accurately weighed quantity of USP Ondansetron Related Compound D RS in Mobile phase; and dilute quantitatively, and stepwise if necessary, with Mobile phase to obtain a solution having a known concentration of about 0.5 µg per mL.

Test solution— Quantitatively dilute, if necessary, an accurately measured volume of Oral Solution with Mobile phase to obtain a solution containing about 0.8 mg of ondansetron per mL.

Chromatographic system (see Chromatography 621)— The liquid chromatograph is equipped with a 328-nm detector and a 4.6-mm × 25-cm column that contains packing L10. The flow rate is about 1.5 mL per minute. Chromatograph the System suitability solution, and record the peak responses as directed for Procedure: the resolution, R, between ondansetron related compound D and ondansetron related compound C is not less than 2.0; the tailing factor for ondansetron related compound D is not more than 2.0; and the relative standard deviation for replicate injections is not more than 4.0%.

Procedure— Separately inject equal volumes (about 20 µL) of the Standard solution and the Test solution into the chromatograph, record the chromatograms, and measure the responses for the major peaks. Calculate the percentage of ondansetron related compound D in the volume of Oral Solution taken by the formula: in which D is the dilution factor for the Oral Solution in the Test solution; CS is the concentration, in µg per mL, of USP Ondansetron Related Compound D RS in the Standard solution; CA is the concentration, in µg per mL, of ondansetron in the Oral Solution, as determined in the Assay; and rU and rS are the peak responses of ondansetron related compound D obtained from the Test solution and the Standard solution, respectively: not more than 0.1% is found.

Mobile phase, System suitability solution, and Chromatographic system— Proceed as directed in the Assay under Ondansetron Hydrochloride.

Standard solution— Prepare as directed for the Standard preparation, in the Assay under Ondansetron Hydrochloride.

Test solution— Use the Assay preparation.

Procedure— Separately inject equal volumes (about 10 µL) of the Standard solution and the Test solution into the chromatograph, record the chromatograms, and measure the peak responses. Calculate the percentage of each related compound in the volume of Oral Solution taken by the formula: in which 293.36 and 329.82 are the molecular weights of ondansetron and anhydrous ondansetron hydrochloride, respectively; F is the relative response factor for each known and unknown impurity (the values of relative response factors [RRF] and the limits can be obtained from Table 1); V is the volume, in mL, of Oral Solution taken; CS is the concentration, in mg per mL, on the anhydrous basis, of USP Ondansetron Hydrochloride RS in the Standard solution; CA is the concentration, in mg per mL, of ondansetron in the Oral Solution; ri is the peak response for any related compound obtained from the Test solution; and rS is the peak response for ondansetron obtained from the Standard solution.

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

Assay preparation— Transfer an accurately measured volume of Oral Solution, equivalent to about 9 mg of ondansetron, 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 216-nm detector and a 4.6-mm × 25-cm column that contains packing L10. The flow rate is about 1.5 mL per minute. Chromatograph the System suitability solution, and record the peak responses as directed for Procedure: the relative retention times are about 1.1 for ondansetron related compound A and 1.0 for ondansetron; and the resolution, R, between ondansetron related compound A and ondansetron is not less than 1.5. Chromatograph the Standard preparation, and record the peak responses as directed for Procedure: the tailing factor 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 10 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 ondansetron (C18H19N3O) in each mL of Oral Solution taken by the formula: in which 293.36 and 329.82 are the molecular weights of ondansetron and anhydrous ondansetron hydrochloride, respectively; C is the concentration, in mg per mL, on the anhydrous basis, of USP Ondansetron Hydrochloride RS in the Standard preparation; V is the volume, in mL, of Oral Solution taken; and rU and rS are the peak responses obtained from the Assay preparation and the Standard preparation, respectively.