Magnetic Ti3C2 MXene Nanosheets Prepared for Enrichment of Phosphopeptides.

MXenes have received lots of attention since discovered and have been applied in various fields. In this work, Ti3C2-Fe3O4 composites with exposed non-modified Ti3C2 MXene nanosheets were designed and prepared by an in situ growth strategy and then applied in the enrichment of phosphopeptides. The two-dimensional composites could interact with the phosphopeptides through a metal oxide affinity chromatography mechanism provided by Ti-O and Fe-O bonds and a hydrophilic interaction chromatography mechanism by surface hydroxyl groups. This magnetic nanomaterial with a specific surface area of 66.1 m2·g-1 had high sensitivity to phosphopeptides (0.5 nmol·L-1) and high selectivity (1:1000 of the molar ratio of ß-casein to bovine serum albumin). Non-fat milk was adopted as a real sample to preliminarily examine the applicability of the Ti3C2-Fe3O4-based protocol. Subsequently, Qingkailing injection, a kind of traditional Chinese medicine injection, was introduced to further explore the suitability of the nanocomposites for phosphopeptide enrichment from more complex matrices and satisfactory results were obtained.

[Determination of five protopanaxadiol ginsenosides in ginseng by solid-phase extraction-ultra performance liquid chromatography].

A new method based on solid-phase extraction-ultraperformance liquid chromatography (SPE-UPLC) was developed for the determination of five protopanaxadiol ginsenosides in ginseng. The ginsenosides were extracted from ground ginseng samples using water-saturated n-butanol and purified on a hydrophilic solid-phase extraction column. Chromatographic separation was achieved on an ACQUITY UPLC BEH Shield RP18 column (100 mm×2.1 mm, 1.7 µm) by linear gradient elution using an acetonitrile/water mobile phase. Five protopanaxadiol ginsenosides were detected by a photodiode array detector, and they showed a strong positive linear correlation (r2>0.999) in the range of 5-500 µg/mL. In addition, the instrument precision ranged between 0.95% and 2.62% (n=6), with the sample stability between 0.90% and 2.15% (n=8) within 22 h. Intra- and inter-day repeatabilities were 5.35%-6.47% (n=6) and 5.56%-6.34% (n=8), respectively. Sample recoveries and the corresponding relative standard deviations (RSDs) were 87.16%-101.92% and 1.54%-4.01% (n=6), respectively. Hydrophilic chromatography materials were used in SPE, and the extract was directly loaded and purified without pretreatment. Besides, with the use of UPLC, the analysis time was greatly shortened. The developed method is simple and rapid, with high throughput, thus being suitable for the quantitative analysis of the five protopanaxadiol ginsenosides in ginsengs.

Separation and characterization of chemical constituents in Ginkgo biloba extract by off-line hydrophilic interaction×reversed-phase two-dimensional liquid chromatography coupled with quadrupole-time of flight mass spectrometry.

Ginkgo biloba extract (GBE), derived from the leaves of Ginkgo biloba L., is one of the most widely used traditional Chinese medicines worldwide. Due to high structural diversity and low abundance of chemical constituents in GBE, conventional reversed-phase liquid chromatography has limited power to meet the needs of its quality control. In this study, an off-line hydrophilic interaction×reversed-phase two-dimensional liquid chromatography (HILIC×RP 2D-LC) system coupled with diode array detection (DAD) and quadrupole time-of-flight mass spectrometry (qTOF-MS) was established to comprehensively analyze the chemical constituents of GBE. After optimizing the chromatographic columns and mobile phase of 2D-LC, a Waters XBridge Amide column using acetonitrile/water/formic acid as the mobile phase was selected as the first dimension to fractionate GBE, and the obtained fractions were further separated on an Agilent Zorbax XDB-C18 column with methanol/water/formic acid as the mobile phase. As a result, a total of 125 compounds were detected in GBE. The orthogonality of the 2D-LC system was 69.5%, and the practical peak capacity was 3864 and 2994, respectively, calculated by two different methods. The structures of 104 compounds were tentatively characterized by qTOF-MS analysis, and 21 of them were further confirmed by comparing with reference standards. This established HILIC×RP 2D-LC-qTOF/MS system can greatly improve the separation and characterization of natural products in GBE or other complicated herbal extracts.

Separation and analysis of phenolic acids from Salvia miltiorrhiza and its related preparations by off-line two-dimensional hydrophilic interaction chromatography×reversed-phase liquid chromatography coupled with ion trap time-of-flight mass spectrometry.

Salvia miltiorrhiza (SM) is one of the most widely used Traditional Chinese Medicine. Active constituents of SM mainly contain hydrophilic phenolic acids (PAs) and lipophilic tanshinones. However, due to the existing of multiple ester bonds and unsaturated bonds in the structures, PAs have numerous chemical conversion products. Many of them are so low-abundant that hard to be separated using conventional methods. In this study, an off-line two-dimensional liquid chromatography (2D-LC) method was developed to separate PAs in SM and its related preparations. In the first dimension, samples were fractionated by hydrophilic interaction chromatography (HILIC) (Acchrom×Amide, 4.6×250mm, 5µm) mainly based on the hydrogen bonding effects. The fractions were then separated on reversed-phase liquid chromatography (RP-LC) (Acquity HSS T3, 2.1×50mm, 1.7µm) according to hydrophobicity. For the selective identification of PAs, diode array detector (DAD) and electrospray ionization tandem ion trap time-of-flight mass spectrometry (ESI-IT-TOF-MS) were employed. Practical and effective peak capacities of all the samples were greater than 2046 and 1130, respectively, with the orthogonalities ranged from 69.7% to 92.8%, which indicated the high efficiency and versatility of this method. By utilizing the data post-processing techniques, including mass defect filter, neutral loss filter and product ion filter, a total of 265 compounds comprising 196 potentially new PAs were tentatively characterized. Twelve kinds of derivatives, mainly including glycosylated compounds, O-alkylated compounds, condensed compounds and hydrolyzed compounds, constituted the novelty of the newly identified PAs. The HILIC×RP-LC/TOF-MS system expanded our understanding on PAs of S. miltiorrhiza and its related preparations, which could also benefit the separation and characterization of polar constituents in complicated herbal extracts.

[Simultaneous determination of 14 organic acids in Shenfu injection by hydrophilic interaction chromatography-tandem mass spectrometry].

Organic acids are widely distributed in plants and related products, and participate in a wide range of metabolic pathways (e.g. tricarboxylic acid cycle), showing diverse pharmacological activities. As a widely used Chinese patent medicine, its adverse reactions are often reported. Therefore, we should further clarify the chemical components of Shenfu injection, and prepare strict quality standards to ensure the safety and effectiveness of its clinical use. Shenfu injection is prepared from red ginseng (steamed roots of Panax ginseng) and black prepared lateral roots of Aconitum carmichaelii (Heishunpian) by using modern extraction process, and organic acids are regarded as one of its main components. In current study, a hydrophilic interaction chromatography (HILIC) coupled with mass spectrometric method (HILIC-LC-MS) was developed and validated for the simultaneous determination of 14 organic acids, including cinnamic acid, ferulic acid, 4-hydroxylbenzoic acid, L-(+)-lactic acid, adipic acid, fumaric acid, caffeic acid, succinic acid, maleic acid, malonic acid, D-malic acid, (-)-shikimic acid, D-tartaric acid, and quinic acid in Shenfu injection. Satisfactory retention and separation were achieved for all organic acids on HILIC chromatographic column. Except cinnamic acid (231 µg•L⁻¹), lactic acid (113 µg•L⁻¹) and malonic acid (32.5 µg•L⁻¹), the limit of quantitation for the remaining 11 compounds were less than 10 µg•L⁻¹. D-Malic acid, malonic acid, quinic acid, L-(+)-lactic acid, and cinnamic acid were observed to have higher contents in Shenfu injection (>1.89 mg•L⁻¹), whereas caffeic acid and adipic acid were undetectable in all batches. Above all, the developed method is suitable for the simultaneous determination of organic acids in Shenfu and some other traditional Chinese medicine injections.

Simultaneous determination of 14 organic acids in Shenfu injection by hydrophilic interaction chromatography-tandem mass spectrometry / 中国中药杂志

Organic acids are widely distributed in plants and related products, and participate in a wide range of metabolic pathways (e.g. tricarboxylic acid cycle), showing diverse pharmacological activities. As a widely used Chinese patent medicine, its adverse reactions are often reported. Therefore, we should further clarify the chemical components of Shenfu injection, and prepare strict quality standards to ensure the safety and effectiveness of its clinical use. Shenfu injection is prepared from red ginseng (steamed roots of Panax ginseng) and black prepared lateral roots of Aconitum carmichaelii (Heishunpian) by using modern extraction process, and organic acids are regarded as one of its main components. In current study, a hydrophilic interaction chromatography (HILIC) coupled with mass spectrometric method (HILIC-LC-MS) was developed and validated for the simultaneous determination of 14 organic acids, including cinnamic acid, ferulic acid, 4-hydroxylbenzoic acid, L-(+)-lactic acid, adipic acid, fumaric acid, caffeic acid, succinic acid, maleic acid, malonic acid, D-malic acid, (-)-shikimic acid, D-tartaric acid, and quinic acid in Shenfu injection. Satisfactory retention and separation were achieved for all organic acids on HILIC chromatographic column. Except cinnamic acid (231 μg•L⁻¹), lactic acid (113 μg•L⁻¹) and malonic acid (32.5 μg•L⁻¹), the limit of quantitation for the remaining 11 compounds were less than 10 μg•L⁻¹. D-Malic acid, malonic acid, quinic acid, L-(+)-lactic acid, and cinnamic acid were observed to have higher contents in Shenfu injection (>1.89 mg•L⁻¹), whereas caffeic acid and adipic acid were undetectable in all batches. Above all, the developed method is suitable for the simultaneous determination of organic acids in Shenfu and some other traditional Chinese medicine injections.

Comprehensive two-dimensional liquid chromatographic analysis of anthocyanins.

Anthocyanins are naturally occurring plant pigments whose accurate analysis is hampered by their complexity and unique chromatographic behaviour associated with on-column conversion reactions. This paper reports the evaluation of off-line comprehensive two-dimensional liquid chromatography (LC×LC) for the analysis of anthocyanins. Hydrophilic interaction chromatography (HILIC) was used in the first dimension in combination with reversed phase liquid chromatography (RP-LC) in the second dimension. For the selective detection of anthocyanins, diode array detection was used, while high resolution quadrupole-time-of-flight mass spectrometry (Q-TOF) was used for compound identification. As application, the HILIC×RP-LC separation of diverse anthocyanins in blueberries, red radish, black beans, red grape skins and red cabbage is demonstrated. Off-line HILIC×RP-LC revealed information which could not be obtained by one-dimensional HPLC methods, while the structured elution order for the anthocyanins simplifies compound identification and facilitates the comparison of anthocyanin content of natural products by means of contour plots.