Solution A, Solution B, Solution C, Mobile phase, Standard solution 1, Standard solution 2, and Chromatographic system— Proceed as directed in the test for Content of pentacyclic oxindole alkaloids and limit of tetracyclic oxindole alkaloids under Cat's Claw.

Test solution— Weigh accurately not fewer than 20 Tablets, and pulverize, using a mortar and pestle. Transfer an accurately weighed quantity of the powder, equivalent to 20 mg of the labeled amount of pentacyclic oxindole alkaloids, to a 50-mL centrifuge tube. Sonicate with 10 mL of methanol for 10 minutes. Centrifuge, and transfer this solution to a 50-mL volumetric flask. Repeat the above extraction three additional times combining the extracts in the 50-mL volumetric flask, and dilute with methanol to volume. Transfer about 3 mL of the solution to a test tube containing 300 mg of polyamide powder, and shake for 1 minute. Pass through a nylon filter having a 0.45-µm or finer porosity, discarding the first part of the filtrate.

Procedure— Proceed as directed in the test for Content of pentacyclic oxindole alkaloids and limit of tetracyclic oxindole alkaloids under Cat's Claw. Calculate the content of each relevant alkaloid, in mg, in the portion of Tablets taken by the formula: in which the terms are as defined therein. Calculate the content of total pentacyclic oxindole alkaloids by adding the individual contents of speciophylline, uncarine F, mitraphylline, isomitraphylline, pteropodine, and isopteropodine. Calculate the content of tetracyclic oxindole alkaloids by adding the individual contents of rhynchophylline and isorhynchophylline: not more than 25% of the labeled amount of pentacyclic oxindole alkaloids is found.