Offline two-dimensional normal-phase × reversed-phase liquid chromatography coupled with high-resolution mass spectrometry for comprehensive analysis of chemical constituents in Euphorbia kansui

Separation, identification, and fingerprinting of antioxidant components in persimmon (Diospyros kaki) leaves by offline two‐dimensional liquid chromatography with electrochemical detection and tandem mass spectrometry

“…Compounds in Figure 3C: gallic acid (1), GC (5), protocatechuic acid (6), neochlorogenic acid (8), catechin (10), chlorogenic acid (12), procyanidin B2 ( 14), p-coumaric acid (17), orientin (18), hyperoside (22), isoquercitrin (23), kaempferol-3-O-galactoside (25), quercetin (36), and kaempferol (37).…”

“…It can be used to separate compounds with different polarities, structures, and properties, and is suitable for a wider range of application scenarios [22][23][24]. Normal phase (NP), reverse phase (RP), and HILIC modes are often combined to improve separation and increase peak capacity [25,26]. The RP mode demonstrates high efficiency when calculating the total peak capacity of the LC×LC system using the product rule, while also exhibiting excellent compatibility between the two dimensions [27].…”

Two Multidimensional Chromatography/High-Resolution Mass Spectrometry Approaches Enabling the In-Depth Metabolite Characterization Simultaneously from Three Glycyrrhiza Species: Method Development, Comparison, and Integration

“…MDC can be operated in either the online or the offline mode, mainly including the applications of two-dimensional liquid chromatography (2D-LC) and three-dimensional liquid chromatography (3D-LC). , By MDC, the column combinations with large separation differences (referred to as high orthogonality) are often pursued. − Online 2D-LC has the merits of high automation, fast analysis speed, and good reproducibility, but it strongly depends on the availability of instruments . In contrast, the offline mode is highly accessible in the laboratories, flexible in integrating different mechanisms of separation, and free of the solvent effect, but often involves complex operations (e.g., eluate collection, solvent removal, and redissolution for sample injection). − In addition, 2D-LC can be divided into the comprehensive (LC × LC) and heart-cutting 2D-LC (HC-2D-LC) modes according to all of the one-dimensional fractions, or part of them are transferred and further separated by second-dimensional chromatography. , Comparatively, the comprehensive 2D-LC is advantageous in separating the complex components by feat of the greatly increased peak capacity and enhanced selectivity in separation, while HC-2D-LC selectively captures or enriches the target component(s), thus is more suitable for the quantitative assays. − Our recent research established two offline 3D-LC strategies by sequentially integrating ion exchange chromatography, hydrophilic interaction chromatography, and reversed-phase chromatography (IEC-HILIC-RPC) prior to the ultimate monitoring by high-resolution mass spectrometry (HRMS), which enabled the efficient discovery of numerous potential unknown structures. The use of a strong anion exchange (SAX) column in the first-dimensional ( 1 D) chromatography fractionated the total extracts of ginseng flowers into the acidic and the neutral fractions, while the application of a strong cation exchange (SCX) column in the 1 D chromatography separated the total extracts of Uncaria sessilifructus into the alkaloids and the nonbasic components .…”

Targeted Offline Two-Dimensional HPLC and UHPLC-Orbitrap-MS Combined with Molecular Networking Reveal the Effect of Processing on Chemical Constituents of Xuetong (the Stem of Kadsura heteroclita)

“…However, it often fails to achieve baseline separation and provide sufficient resolution when analyzing complex samples. Two-dimensional LC integrates multiple separation mechanisms, such as reverse phase (C 18 ) liquid chromatography (RPLC), hydrophilic interaction chromatography (HILIC), and normal phase liquid chromatography (NPLC), which enable compounds to undergo dual separations, significantly enhancing both peak resolution and capacity [11,12]. Mass spectrometry (MS) techniques are widely employed for identifying the structure of natural products, but the complexity and vast amount of data pose challenges in data processing.…”