Serial hyphenation of dried spot, reversed phase liquid chromatography, hydrophilic interaction liquid chromatography, and tandem mass spectrometry towards direct chemical profiling of herbal medicine-derived liquid matrices, an application in Cistanche sinensis

Abstract

Inspired by dried blood spots (DBS), “dried spots of herbal medicines” (DSHM) concept was proposed here. In response to this superior sampling means, a new platform integrating dried spot, serially coupled reversed phase liquid chromatography and hydrophilic interaction liquid chromatography (RPLC-HILIC), and tandem mass spectrometry (MS/MS), was configured for directly, comprehensively chemical profiling of HM-derived liquid matrices. As an important original source of Cistanches Herba (Chinese name: Roucongrong) that is a well-known tonic HM, Cistanche sinensis (Csi) was employed to illustrate and validate the applicability. Dried spots (I.D. 3.0 mm) were prepared by loading 2 μL aliquots of Csi extract onto filter paper. Each dried spot was packed into an in-line filter holder (I.D. 3.0 mm × 4.0 mm) and then inserted behind the auto-sampler of a well-defined instrumentation named RPLC-HILIC–MS/MS. Hybrid ion trap-time of flight MS and hybrid triple quadrupole-linear ion trap MS were deployed in combination for the in-depth MS/MS data acquisition of diverse chemical families, such as phenylethanoid glycosides, lignans, iridoids, amino acids, and so forth. To assist chemical profiling, an in-house chemical library was built by collecting as much prior knowledge as possible. A total of 88 components were detected and tentatively annotated in Csi by matching their multi-stage MS spectra with those of authentic standards and literature data. Collectively, DSHM carried all merits of DBS, and the integrative dried spot-RPLC-HILIC-MS/MS platform was a promising analytical tool for direct chemical analysis and rapid quality evaluation of HMs, in particular those traditional Chinese medicine injections.