Investigation of Adsorption and Desorption Properties of Total Ginsenosides on Anion-exchange Resins and Its LC-MS Analysis / 中国实验方剂学杂志

Objective:To compare the adsorption and desorption properties of different anion exchange resins for total ginsenosides， clarify their adsorption/desorption mechanism， and establish a simple protocol for the purification of total ginsenosides. Method:The adsorption and desorption properties of five different resins （D301， D315， D312， D330， D201） on total ginsenosides were evaluated with specific adsorption capacity， specific desorption capacity， desorption rate and recovery rate as indices. The adsorption kinetics and thermodynamics of the selected resin and D101 macroporous resin were investigated by pseudo-first-order and pseudo-second-order kinetic models， as well as Langmuir and Freundlich isothermal adsorption models， and the differences of adsorption mechanism between anion exchange resin and conventional macroporous resin were elucidated. The dynamic adsorption and desorption experiments were used to determine the optimum chromatographic parameters for anion exchange resin. After verifying the purification process of total ginsenosides， nine individual ginsenosides were qualitatively and quantitatively analyzed by liquid chromatography-mass spectrometry （LC-MS）. Result:D301 anion exchange resin was obviously superior to the other four kinds of anion exchange resin， the optimum parameters were set as follows：pH 8 of loading solution， loading volume of 2 BV， loading speed of 4 BV·h^-1， eluted with 3 BV of water and 20% ethanol for the impurities， eluted with 8 BV of 80% ethanol with elution speed of 4 BV·h^-1. After purified by D301 resin， the enrichment coefficients of 9 monomer ginsenosides were simultaneously increased to different degrees， the overall enrichment coefficient was up to 5.3， the recovery rate for the total amount of these ginsenosides was calculated to be 80.9%， and the purity of total ginsenosides in Ginseng Radix et Rhizoma extract increased from 17.07% to 91.19%. Conclusion:D301 anion exchange resin is suitable for rapid and practical purification of total ginsenosides， hence allowing for the enrichment of high-purity total ginsenosides from Ginseng Radix et Rhizoma via one-dimensional column chromatography.

Preferential adsorption of flavonoids and organic acids by amino-modified Fe3O4 nanoparticles (MNP-NH2) / 中草药

Objective To synthesize amino-modified Fe3O4 nanoparticles (MNP-NH2) and study the adsorption of flavonoids and organic acids by MNP-NH2. Methods MNP-NH2 were synthesized and characterized by transmission electron microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, and vibrating sample magnetometer analysis; The adsorption rule of MNP-NH2 was discussed by studying the adsorption properties of 12 monomers. The adsorption properties of MNP-NH2 were assessed under conditions of different ultrasonic time, temperature, ionic strength, and pH. The final elution conditions were determined by L9(34) orthogonal test and the recycling performance was also considered. Results MNP-NH2 synthesized in this study have stable structure, uniform distribution, and good magnetic properties. Adsorption of 12 monomers by MNP-NH2 showed that the mechanism of adsorption was related to the number of ortho-phenolic hydroxyl groups. Ions concentration and temperature had little effect on adsorption for different compounds except pH. The optimized adsorption conditions were extraction for 40 min at 30 ℃ and the final elution conditions were determined to be 5 mL of 20% glacialacetic acid (methanol-water 60∶40) and ultrasonication for 40 min. Conclusion MNP-NH2 can be utilized to extract the effective components of Lonicerae Japonicae Flos and maintain a high adsorption rate of flavonoids. Moreover, MNP-NH2 had great recycling and reproducibility, providing new ideas for the utilization of extracting chemical compounds from complex traditional Chinese medicine and natural medicines.

Preparation of galangin molecular imprinted polymers on silica gel surface and its adsorption properties / 中草药

Objective To prepare surface molecular imprinted polymers (MIP) of galangin by using surface molecular imprinting technique. Methods Galangin MIP was prepared by surface polymerization method at the surface of silica gel, which was modified with (3-aminopropyl) trimethoxysilane, by using galangin as the template molecule, methacrylic acid (MAA) as the functional monomer, and N,N′-methylenebisacrylamide (MBA) as crosslinking agent. The polymer was characterized by infrared spectroscopy and scanning electron microscopy. And its adsorption properties were studied by static and competitive adsorption method. Results The experimental research showed that the optimal preparation condition was that the molar ration of galangin to MAA was 1∶4, with molar ration of MAA to MBA 1∶7, reaction temperature 40 ℃ and reaction time 12 h. Infrared spectrum and scanning electron microscopy showed that MIP was successfully grafted on the surface of silica gel, and recognition holes and sites selectively appeared for galangin molecules. Adsorption experiments exhibited that MIP had specific recognition and good affinity for galangin molecules. Compared to the controls of breviscapine and luteolin, the selectivity coefficients of MIP to galangin were 11.2 and 5.3, respectively. Conclusion MIP has good recognition and high selectivity for galangin, which provides a new method for the separation and extraction of flavonoids from Chinese medicine.

Preparation of Polyacrylamide Resin and Its Adsorption Properties on 2,4-Dichlorophenoxyacetic Acid / 分析化学

Polyacrylamide resin was synthesized via surface-initiated atom transfer radical polymerization ( SI-ATRP) method. Acrylic amide ( AM) was grafted onto the surface of the chloromethyl polystyrene resin via SI-ATRP in the CuBr/2, 2'-bipyridine ( Bpy) system as catalyst at room temperature. The compositions of polyacrylamide resin were determined by means of elementary analysis, FT-IR analysis and scanning electron microscopy ( SEM) . The adsorption properties, the parameters of kinetics and the thermodynamics of the resin were evaluated in details, respectively. As the results, adsorption capacity of 2,4-dichlorophenoxyacetic acid (2,4-D) increased with the initial concentrations of solution increasing at room temperature, and its highest adsorption capacity was 111. 0 mg/g with solution concentration of 8 mmol/L. Adsorption isotherm at room temperature was determined and modeled with Langmuir and Freundlich equations. The thermodynamic equilibrium functions were calculated to be ΔG0, hence, the adsorption was spontaneous, endothermic and entropy increasing. The kinetics fitted the pseudo-second-order well. The polyacrylamide-chloromethyl polystyrene (PAM-CMCPS) resin was used for the adsorption of 2,4-D in orange sample, and good results were obtained.

Preparation and Evaluation of Core-Shell Resveratrol Molecularly Imprinted Microspheres / 分析化学

Employing resveratrol as template molecule, acrylamide as functional monomer and ethyleneglycol dimethacrylate as cross-linkers, a core-shell resveratrol imprinted microspheres was prepared based on the surface of SiO_2 with a surface imprinting technique.The molecularly imprinted microsphere was characterized by infrared spectroscopy and scanning electron microscopy, and the results showed that the surface grafting of molecularly imprinted polymer-shell particle on SiO_2 was successful and the particles were evenly distributed.High performance liquid chromatography was also used to investigate the imprinted microsphere adsorption per formance, and the results showed that the imprinted microsphere exhibited good recognition performance.The maximum adsorption capacities were Q_(maxl)=9.087 mg/g and Q_(max2)= 13.80 mg/g by the model of Scatchard analysis.The imprinted micospheres was applied to separate resveratrol from the extraction of rhizoma polygoni cuspidate successfully.