Lei Chen

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Name: 陈磊
Organization: Tianjin University , China
Department:
Title: Associate Professor(PhD)
Co-reporter:Xianhua Wang;Qiuxue Fang;Shipeng Liu
Journal of Separation Science 2012 Volume 35( Issue 12) pp:1432-1438
Publication Date(Web):
DOI:10.1002/jssc.201200096

The combination of molecularly imprinted polymer with high performance liquid chromatography has been developed to determine cyromazine and its metabolic melamine in some samples. However, the potential risk of template leakage used in molecularly imprinted polymer is a major disadvantage. To solve this problem, 2-(4,6-diamino-1,3,5-triazin-2-ylamino) ethanethiol disulfide, a molecule that shares the similar imprinting sites with cyromazine and melamine, was selected as pseudo template to prepare molecularly imprinted polymer. Methacrylic acid, ethylene glycol dimethyl acrylate and toluene were selected as functional monomer, crosslinker and porogen, respectively. The molecular recognition property and binding capability of cyromazine and melamine were evaluated by adsorption test and Scatchard analysis. The results showed that the molecularly imprinted polymer based on pseudo template had more excellent affinity and selectivity for cyromazine and melamine. The resulting molecularly imprinted polymer was used as a solid-phase extraction material to enrich cyromazine and melamine in egg and milk samples for high performance liquid chromatography analysis. The solid-phase extraction process was carefully optimized. It was found that when different concentration of cyromazine and melamine standards were spiked into samples, satisfactory recovery rate of cyromazine and melamine were obtained as 85.6–98.8% with relative standard deviation <5.5%.

Co-reporter:Hongling Wang, Jingjing Cao, Yanping Bi, Lei Chen, Qian-Hong Wan
Journal of Chromatography A 2009 Volume 1216(Issue 31) pp:5882-5887
Publication Date(Web):31 July 2009
DOI:10.1016/j.chroma.2009.06.017
Fabrication of porous frits to retain stationary phases is a critical issue in column preparation for capillary electrochromatography (CEC). In this work, porous frits were prepared by applying an external magnetic field to magnetically responsive particles placed inside a fused-silica capillary. Three batches of uniform magnetite spheres with particle diameters of 0.3, 0.4, and 0.6 μm and saturation magnetization values of 73.03, 74.41, and 77.83 emu/g, respectively, were used as frit particles and octadecyl- and phenyl-bonded silica gels were packed successfully into frit-containing capillaries. The performance of the resulting magnetically immobilized frits and packed columns was evaluated. The electroosmotic mobilities in capillaries containing outlet frit only were found to be reduced by 2–4% whereas the plate heights of an unretained marker increased by 30–50% as compared to those in open capillaries. These variations are believed to be associated with the inhomogeneities of the packed structure of the frits. The magnetically immobilized frits showed adequate mechanical strength to withstand the flow drag force, allowing separation in capillaries packed with 5-μm stationary phases up to 10–15 cm, thus rendering column efficiency and reproducibility comparable with those obtained with sintered frits. Taken together, retaining frits made of uniform magnetite particles serves as a viable alternative to sintered frits for column preparation, which offers several distinct advantages such as ease of preparation, improved durability as compared to sintered frits where the removal of the polyimide coating makes the packed column susceptible to breakage, and use of large-bore capillaries for semipreparative separations.
Co-reporter:Zhi-Qiang GUO, Dan XU, Qian-Hong WAN, Lei CHEN
Chinese Journal of Analytical Chemistry 2009 Volume 37(Issue 2) pp:232-236
Publication Date(Web):February 2009
DOI:10.1016/S1872-2040(08)60086-9
(3beta,5alpha,25S)-spirost-7(8)-en-3-yl O-beta-D-glucopyranosyl-(1?2)-O-[beta-D-xylopyranosyl-(1?3)]-O-beta-D-glucopyranosyl-(1?4)-beta-D-galactopyranoside
(3beta,5alpha,25R)-spirost-7(8)-en-3-yl O-beta-D-glucopyranosyl-(1?2)-O-[beta-D-xylopyranosyl-(1?3)]-O-beta-D-glucopyranosyl-(1?4)-beta-D-galactopyranoside
(3beta,5alpha,25R)-spirost-9(11)-en-3-yl O-beta-D-glucopyranosyl-(1?2)-O-[beta-D-xylopyranosyl-(1?3)]-O-beta-D-glucopyranosyl-(1?4)-beta-D-galactopyranoside
(3beta,5alpha,17alpha,25S)-17-hydroxyspirost-9(11)-en-3-yl O-beta-D-glucopyranosyl-(1?2)-O-[beta-D-xylopyranosyl-(1?3)]-O-beta-D-glucopyranosyl-(1?4)-beta-D-galactopyranoside
(3beta,5alpha,25S)-spirost-9(11)-en-3-yl O-beta-D-glucopyranosyl-(1?2)-O-[beta-D-xylopyranosyl-(1?3)]-O-beta-D-glucopyranosyl-(1?4)-beta-D-galactopyranoside
(R)-3-(3-Hydroxy-4-methoxyphenyl)-beta-alanine
5H-Benzo[a]phenoxazin-5-one, 9-(diethylamino)-2-(2-propenyloxy)-
4-PROPYLBIPHENYL