Simultaneous Analysis of Macamides in Maca (Lepidium meyenii) with Different Drying Process by Liquid Chromatography Tandem Mass Spectrometry

摘要

Macamides with benzylalkylamides structure are a group of characteristic constituents isolated from functional food Maca (Lepidium meyenii Walp.). Previous study demonstrated that macamides are secondary amides, the accumulation of which is associated with drying process. In this study, a rapid method based on ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) is developed for the simultaneous detection and determination of macamides in Maca. Validation parameters including linearity, limit of detection, limit of quantification, accuracy, precision, repeatability, and stability were all within the required limits. Seven major macamides are determined by the UPLC method with detection wavelength at 205 nm in 12 min. Based on the fragmentation pattern of standard compounds, four fragment ions (m/z 91, 108, 121, and 138) are selected as diagnostic ions for detection of macamides through precursor ion acquisition mode. Additionally, comparative analysis is performed to examine the effects of different drying processes (air-drying, oven-drying, freeze-drying, and steaming) on Maca (whole hypocotyls and pieces) for macamides. Whole hypocotyls with oven-drying showed the highest content of macamides (2.528 mg/g), while freeze-drying and steaming significantly decrease the amount of macamides. The results provide a reliable method for analysis of macamides and extend previous work insights into the drying process of Maca.