Development and validation of a UPLC-DAD-MS method for characterization and quantification of alkaloids in Menispermi Rhizoma and its preparations

Menispermi Rhizoma (MR), a well known traditional Chinese medicine, is widely used to prevent and treat sore throat, enteritis, dysentery and rheumatoid arthralgia clinically. However, many rhizomes of Chinese herbal medicines are mistaken as MR due to their similar appearance, which could affect MR quality and cause serious consequences for patients. To guarantee the quality of MR products, an ultra-high-performance liquid chromatography–diode array detector–tandem mass spectrometry (UPLC-DAD-MS) method was established for the characterization of major active ingredients in MR and its preparations. By comparing their retention times and characteristic fragmentations with those of authentic compounds, nine alkaloids in MR were unequivocally identified as acutumidine, acutumine, magnoflorine, menisperine, dauricine, menisporphine, N-demethyl-N-formyldehydronuciferine, 6-O-demethylmenisporphine and dauriporphine. Quantitative analysis of the nine alkaloids in MR and its preparations was accomplished by UPLC-DAD. A UPLC C18 column was employed for the chromatographic separation which was effected by a gradient elution with acetonitrile and 0.1% aqueous formic acid solution containing 5mM ammonium acetate at a flow rate of 0.3mL/min. This quantitative method was validated with good linearity (R2≥0.9991), desirable intra- and inter-day precisions (RSD≤3.32%), and acceptable recoveries (97.90–106.8%). The method was also successfully applied to quantify nine alkaloids in eight batches of MR, six batches of MR capsules and two batches of MR pills. A counterfeit MR sample from Henan province was identified by the validated method, followed by further verification by appearance and microscopic identification. The developed UPLC-DAD-MS method overcame the shortcomings of other quality control methods, such as scant chemical marker, long analytical time, consumption of large amounts of organic solvents and limitation to MR or its single dosage form.