Development and Validation of a HPLC–MS/MS Method for Quantification of Andrographolide in Rat Plasma by Using Lithium Adduct Detection

In this study, a simple high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method has been developed for quantification of andrographolide in rat plasma using andrographolide-lithium adduct as the precursor ion for the first time. The addition of lithium carbonate into the mobile phase could increase the mass response of andrographolide by approximately 100-fold. The analytes were retained and separated on a C18 column and analyzed using a triple quadrupole mass spectrometer equipped with an ESI source. Andrographolide exhibited excellent retention on the C18 column under optimized chromatographic conditions. A simple protein precipitation pretreatment resulted in high extraction recovery (approximately 100%) and negligible matrix effects. The method was linear over the concentration range of 2.00-1606.00 ng/mL. Both precision and accuracy were within acceptable limits. This simple HPLC-MS/MS method has been validated and successfully applied to support pharmacokinetic studies of andrographolide in Sprague-Dawley rats. The present study also provided a strategy for improving the mass response of drugs with low ionization efficiency, especially compounds from plants.