Time filter

Source Type

Li Z.,Chongqing University | Li J.,Chongqing University | Huo D.,Chongqing University | Yang M.,Chongqing University | And 4 more authors.
Key Engineering Materials

The integration of molecular imprinting technique and solid-phase extraction (SPE) implements an effective alternative for sample pre-concentration in the determination and analysis of veterinary drug/pesticide residues. Herein, we reports a preliminary study on the preparation of streptomycin imprinted polymers on the surface of silica micro-spheres (with an average size of 50μm) and nano-spheres (with an average size of 500nm) via sol gel method. A mixed solution of tetrahydrofuran, ethanol and water (volume ratio is 7:1:1) was choose as dispersion agent, 3-aminopropyltriethoxysilane and phenyltriethoxysilane as functional monomers, and tetraethyl orthosilicate as cross-linker, while ammonia solution served as catalyst in the polymerization process. Scanning electron microscopic characterization was employed, suggesting that activating time exerts important influences on the morphology of activated silica micro-spheres, and also resultant molecular imprinted polymers (MIPs). The absorption capacity and selectivity of the obtained two MIPs were also evaluated for streptomycin and its analogue compounds in water samples. The results illustrate that the streptomycin-imprinted silica micro-spheres (MMIP) exhibited both larger absorption capacity and higher selectivity than those of silica nano-spheres (NMIP). The variant analytical performance might result from inadequate polymerization on the surface of silica nano-spheres. © 2013 Trans Tech Publications Ltd, Switzerland. Source

Li Y.,Chongqing University | Li Y.,Chongqing Engineering Research Center for Import and Export Food Safety | Chen Y.,China Agricultural University | Li Z.,Chongqing University | And 8 more authors.
Journal of Chromatographic Science

This paper describes the preparation of a novel mixed-bed immunoaffinity chromatography (IAC) column by coupling four monoclonal antibodies against different sulfonamides (SAs) to Sepharose 4B. The IAC column can be used to simultaneously extract and purify 16 SAs in pork muscle. The dynamic column capacities for all SAs in mixed standard solution were between 312 and 479 ng/mL gel. After simple extraction and IAC cleanup, the sample solution can be directly injected for liquid chromatography-ultraviolet analysis. The recoveries of SAs from spiked samples at levels of 25, 50 and 100 g/kg ranged from 83.3 to 103.1 with variation coefficient less than 8.6. The comparison of IAC with liquidliquid extraction and solid phase extraction indicated that IAC has better purification effect and needs less organic solution than conventional methods, thus it would be an ideal method for selective purification of SAs in pork muscle. © 2012 The Author. Source

Li J.,Chongqing University | Yang M.,Chongqing University | Huo D.,Chongqing University | Hou C.,Chongqing University | And 3 more authors.
Journal of Separation Science

Streptomycin-imprinted silica microspheres were prepared by combining a surface molecular-imprinting technique with the sol-gel method. A mixture of tetrahydrofuran, ethanol, and water (6:1:1, v/v/v) was selected as dispersing solvent while 3-aminopropyltriethoxysilane and triethoxyphenylsilane acted as functional monomers, and tetraethyl orthosilicate as a cross-linker. Characterization of the molecularly imprinted polymers was conducted using scanning electron microscope and dynamic binding experiments. As compared to the nonimprinted polymers, the imprinted polymers exhibited a higher degree of saturated adsorption volume up to 26.3 mg/g, and better selectivity even in an aqueous solution with interfering compounds, including dihydrostreptomycin, neomycin, and tetracycline. The adsorption ability and selectivity were observed to be influenced by the mole ratio of 3-aminopropyltriethoxysilane and triethoxyphenylsilane. Feasibility of the polymers to be used for actual application was also evaluated with spiked samples, indicating great potential for large-scale applications. Moreover, the streptomycin-imprinted polymers can be repeatedly used for 12 cycles without losing original performance, which is beneficial for commercial use. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

Discover hidden collaborations