A: Infrared Absorption 197K.

B: It meets the requirements of the test for Tartrate 191.

C: The retention time of the morantel peak in the chromatogram of the Test solution corresponds to that in the chromatogram of Standard solution 1, as obtained in the test for Related compounds.

Solution— Dissolve and dilute 0.25 g to 25.0 mL in carbon dioxide-free water.

Mobile phase— Mix 3.5 mL of triethylamine and 850 mL of water. Adjust with phosphoric acid to a pH of 2.5. Add 50 mL of tetrahydrofuran and 100 mL of methanol, and mix.

Tartrate solution— Prepare a solution containing about 0.15 mg of tartaric acid per mL in Mobile phase.

Standard solution 1— Dissolve an accurately weighed quantity of USP Morantel Tartrate RS in Mobile phase to obtain a solution having a known concentration of about 5.0 µg per mL.

Standard solution 2— Dilute 2.0 mL of Standard solution 1 to 100.0 mL with Mobile phase.

System suitability solution— Expose 10 mL of Standard solution 1 to daylight for 15 minutes before injection.

Test solution— Dissolve an accurately weighed quantity of Morantel Tartrate in Mobile phase to obtain a solution having a concentration of about 0.5 mg per mL.

Chromatographic system (see Chromatography 621)— The liquid chromatograph is equipped with a 226-nm detector and a 4.6-mm × 25-cm column that contains 5-µm packing L1. The flow rate is about 0.75 mL per minute. Chromatograph the Tartrate solution, Standard solution 1, and the System suitability solution, and record the peak areas as directed for Procedure: using the System suitability solution, the resolution, R, between morantel and its preceding peak ((Z)-isomer) is not less than 2. The relative retention times are about 0.8, 1.0, and 1.2 for the morantel (Z)-isomer, morantel, and the morantel 4-methyl isomer (1-methyl-2-[(E)-2-(4-methylthiophen-2-yl)ethenyl]-1,4,5,6 tetrahydropyrimidine), respectively.

Procedure— Separately inject equal volumes (about 20 µL) of the Tartrate solution, Standard solution 1, Standard solution 2, and the Test solution into the chromatograph, record the chromatograms, and measure the areas for the major peaks. Disregarding the tartrate peak and any peak in the chromatogram of the Test solution less than the area of the principal peak in the chromatogram of Standard solution 2, calculate the area percentage of each impurity, relative to morantel, in the portion of Morantel Tartrate taken by the formula: in which CS and CU are the concentrations of morantel tartrate, in mg per mL, of Standard solution 1 and the Test solution, respectively; and ri and rS are the peak areas of each individual impurity and morantel obtained from the Test solution and Standard solution 1, respectively: not more than 3% of the morantel 4-methyl isomer is found; not more than 0.5% of any other individual impurity is found; and not more than 1% of total other individual impurities is found.