Simultaneous Determination and Comparison of Phenolic Bioactives among Three Main Kinds of Edible Chrysanthemums.

In this study, we report a simple and reliable high-performance liquid chromatography coupled with diode array detection method for simultaneous and quantitative analysis and comparison of major phenolic compounds dominant phytochemicals in Chrysanthemum morifolium, Florists chrysanthemum and snow chrysanthemum (Coreopsis tinctoria or C. tinctoria). The chromatographic separation was achieved using a reversed phase C18 column with a mobile phase of water [containing 0.1% trifluoroacetic acid (TFA)] and acetonitrile. The major phenolic compounds were completely separated within 16 min at a flow rate of 1.0 mL/min. Flavonoid and phenolic acid profiles of the ethanol extracts of the three flowers were analyzed. The results revealed that C. tinctoria possessed the highest amount of flavonoids (flavanomarein, flavanokanin, marein and okanin) and relative lower content of phenolic acid (chlorogenic acid and 3,5-dicafeoylquinic acid). The total content of the four flavonoids in C. tinctoria reached 53.99 ± 1.32 mg/g. In particular, the marein content in C. tinctoria was as high as 36.50 mg/g. Flavanomarein was only detected in C. tinctoria, whereas chlorogenic acid and 3,5-dicafeoylquinic acid were abundant in Chrysanthemum morifolium and Florists chrysanthemum. The content of marein in Chrysanthemum morifolium was slightly higher than that in Florists chrysanthemum, whereas no okanin was detected in Florists chrysanthemum under these high-performance liquid chromatography conditions. The results indicated phenolic components differ significantly depending on the cultivar, especially between C. tinctoria and common commercially available chrysanthemums. The method adopted in this study is helpful for quality control of different chrysanthemum species as well as their products, which is essential for usage and functionality clarification.

Chiral stationary phase based on cellulose derivative coated polymer microspheres and its separation performance.

Chiral stationary phases (CSPs) have always been research hotspot in enantiomer separation. Currently, most of the CSPs are based on silica platform. In this research, monodisperse, porous glycidyl methacrylate-divinylbenzene copolymer particles (poly(GMA-DVB)) were designed and prepared. Then the GMA was further reacted with ethylenediamine to introduce amino groups onto the polymer, which provide anchoring sites for cellulose derivatives. Herein, Cellulose-tris (3,5-dimethylphenylcarbamate) (CDMPC) was successfully coated onto the polymer microspheres, achieving a stable and successful CSP. The porous structure and the surface moieties of the CSPs were studied in detail. The chromatographic separation was optimized. Hexaconazole,methyl DL-mandelate,benzoin and tebuconazole have been successfully separated on the CSP column, with column efficiency as high as 10,200 plates/m, which is comparable with some silica-based CSPs. The research has indicated that the poly(GMA-DVB) is a promising candidate for constructing CSPs for chiral separation.

Supercritical fluid CO2 extraction of three polymethoxyflavones from Citri reticulatae pericarpium and subsequent preparative separation by continuous high-speed counter-current chromatography.

Polymethoxyflavones (PMFs) are widely found in Citri Reticulatae Pericarpium (CRP) and have been investigated with a broad spectrum of biological activities as well as health promoting properties. However, separation of the PMFs from a complex sample, especially preparative separation of these PMFs with high purity, remains challenging. In the present study, an efficient method based on supercritical fluid extraction (SFE) and continuous high-speed counter-current chromatography (HSCCC) has been developed for extracting and preparative purification PMFs from CRP. Various experimental conditions were investigated to optimize the SFE and HSCCC processes. Under these optimized conditions, crude extract of CRP (extract I) was obtained with a maximum contents of nobiletin, 3,5,6,7,8,3',4'-heptamethoxyflavone and tangeretin. Further extraction of crude extract I was carried out to obtain crude extract II, which was further isolated and purified by HSCCC. It was worth mentioned that continuous injection HSCCC process were realized without lost of separation efficiency, which allowed for multiple purification cycles and therefore saved a lot of labor and time. Furthermore, high-performance liquid chromatography (HPLC) was employed to analyze the fractions separated by HSCCC, which revealed that the purities of the three PMFs were all above 98%. The structures of the three PMFs were identified by LC-MS and 1H NMR spectroscopy.

Investigation on performance of zirconia and magnesia-zirconia stationary phases in hydrophilic interaction chromatography.

In the current study, zirconia (ZrO2) and its composite, magnesia-zirconia (MgO-ZrO2), were prepared as the hydrophilic interaction chromatographic (HILIC) stationary phases (SPs). Different experimental variables including water content, pH and buffer concentration in the mobile phase (MP) as well as column temperature were systematically studied to permit an in-depth understanding of the chromatographic properties of the mentioned SPs and to explore the retention mechanism further on. The results were compared with a native SiO2 column. Adsorption was demonstrated as the main retention mechanism on the two ZrO2-based SPs. The transferring of the analytes from the MP to the ZrO2-based SPs was endothermic and high column temperature would facilitate the retention. In addition, the MgO-ZrO2 SP exhibited superior resolution, column efficiency as well as stronger retention in comparison to the bare ZrO2 SP, which demonstrated that the introduction of MgO could improve the structure and properties of the material. In conclusion, MgO-ZrO2 was a promising material for HILIC applications.