Determination of Stachydrine and Leonurine in Herba Leonuri and Its Succedaneum—Herba Lagopsis—with a Sensitive HPLC–MS/MS Method

A new HPLC–MS/MS method was developed and validated for simultaneous determination of stachydrine and leonurine (two main bioactive alkaloids) in Herba Leonuri and its succedaneum—Herba Lagopsis. Chromatographic separation was performed on an Agilent Eclipse Plus C18 (100 mm × 2.1 mm, 3.5 µm) and methanol–0.1% formic acid solution (20:80) was used as a mobile phase at a flow rate of 0.2 mL/min. With positive electrospray ionization interface, the two alkaloids were detected and quantified by multiple reaction monitoring mode with the transitions of m/z 144.2.2→58.1 for stachydrine and m/z 312.2→181.1 for leonurine. The limits of detection of stachydrine and leonurine were 2.3 and 1.0 pg, respectively. The applicability of this analytical approach was confirmed by the successful analysis of the samples of the two herbs. The established method was validated to be sensitive and reliable for the determination of stachydrine and leonurine in Herba Leonuri. It was demonstrated that Herba Lagopsis also comprised...