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Zhao B.B.,Henan University of Technology | Wang F.Y.,Nanjing University of Science and Technology | Li T.,Dalian Elite Analytical Instruments Co.
Asian Journal of Chemistry | Year: 2015

Micrometer-sized mesoporous silica particles have been synthesized by a modified polymerization induced colloid aggregation method. Silica particles with particle size in the range of 2-5 μm could be obtained by controlling the reaction conditions. The obtained silica particles were characterized by scanning electron microscopy (SEM), N2 physisorption technique and inductively coupled plasma emission spectroscopy (ICP-AES). The C18-modified silica particles were explored as stationary phase in reversed phase liquid chromatography and its chromatographic characteristics for separation of some small molecules have been studied. Source

Li S.,Dalian Elite Analytical Instruments Co. | Feng S.,Dalian Elite Analytical Instruments Co. | Chen Y.,Dalian Elite Analytical Instruments Co. | Li T.,Dalian Elite Analytical Instruments Co. | Li T.,Liaoning Dalian Elite Analytical Instruments Engineering Research Center
Chinese Journal of Chromatography (Se Pu) | Year: 2014

An analytical method for the determination of the activity of transglycosidase in dia-static enzyme by high performance liquid chromatography (HPLC) was established. Taken as the substrate, maltose was transformed into trisaccharide by transglycosidase in a 37 °C water bath and acetic acid buffer solution (PH = 4. 8) with acarbose as transglycosidase inhibitor. The transformation of the trisaccharide was detected on a SUGAR SH1011 column (300 mm × g.O mm, 6 μm) with 0. 01 mol/L sulfuric acid solution as mobile phase at a flow rate of 0. 6 mL/min and a differential refractive index detector (RID), in order that the activity of transglycosidase can be measured indirectly. The conditions such as the chromatographic conditions, the concentration of substrate, the usage of inhibitor, and the incubation time were investigated. Under the optimized separation conditions, the calibration curve of the trisaccharide showed good linearity within the mass concentrations of 0. 1-10 g/L (r=0. 999 8). The limit of detection and the limit of quantitation for transglycosidase activity were 0. 013 U and 0. 043 U, respectively. The relative standard deviation was 0. 63% for six parallel tests. The activities of transglycosidase from different batches of diastatic enzyme were also determined with good result. The method can be applied to determine the activity of transglycosidase in the diastatic enzyme of the producers' raw materials with the advantages of convenience, simplicity and stability. Source

Zhao B.,Henan University of Technology | Zhang Y.,Nanjing University of Science and Technology | Tang T.,Nanjing University of Science and Technology | Tang T.,Dalian Elite Analytical Instruments Co. | And 3 more authors.
Particuology | Year: 2015

Abstract Ultra-pure mesoporous silica microspheres with good monodispersity were synthesized in two steps: nanometer-sized silica sol was produced by the sol-gel process, then micrometer-sized silica microspheres were synthesized by polymerization-induced colloid aggregation of the silica sol. The total metal content of the microspheres was extremely low, which eliminated the tailing of chromatographic peaks by chelating reagents. The pore structure of the silica microspheres could be controlled by altering the sol-gel conditions. The silica microsphere particle size could be adjusted by using different polymerization-induced colloid aggregation conditions. © 2014 Chinese Society of Particuology and Institute of Process Engineering, Chinese Academy of Sciences. Source

Yang S.,Nanjing University of Science and Technology | Tang T.,Nanjing University of Science and Technology | Tang T.,Dalian Elite Analytical Instruments Co. | Li T.,Dalian Elite Analytical Instruments Co. | And 2 more authors.
Chinese Journal of Chromatography (Se Pu) | Year: 2016

The optical absorption detector is one of the most commonly used detectors for high performance liquid chromatography (HPLC). As a core part of this kind of detector, the designs of flow cells, where light passes through samples for acquiring samples information, will affect the performance of a detector. In order to enhance the signal to noise ratio of detectors and reduce the bands broadening that come from flow cells, it is necessary to design a flow cell with a longer optical path length and a less cell volume while maintaining the luminous flux. However the limitations of the machining capacity make it difficult to increase the optical path length, reduce the cell volume and keep or increase the luminous flux simultaneously. It is a challenge to optimize the designing and machining of flow cells so as to improve the performance of detectors. This review discusses the development of designing flow cells based on the detection principle in some aspects of increasing the optical path length, reducing the cell volume, taking the advantages of total reflection and so on. At the same time, some of the designs are illustrated in detail. These various ideas and structures are significant references for designing flow cells and developing optical absorption detectors. Source

Zhao B.,Nanjing University of Science and Technology | Zhang Y.,Nanjing University of Science and Technology | Tang T.,Nanjing University of Science and Technology | Tang T.,Dalian Elite Analytical Instruments Co. | And 4 more authors.
Progress in Chemistry | Year: 2012

High performance liquid chromatography is not only a useful analytical technique, but also an effective preparation method. The availability of a variety of stationary phases for column has been a key factor in the development of HPLC as a major scientific tool. With the most desirable compromise of properties that provide for effective and reproducible separations, silica has been the most widely used HPLC packing material. The silica microspheres are synthesized by various methods, including spray drying, sol-gel, polymerization induced colloid aggregation and templating methods. In recent years, atypical types of silica are prepared and applied in HPLC, such as sub-2μm silica particles, superficially porous silica particles, bimodal silica particles, mesoporous silica particles, organic/silica hybrid particles, etc. As a result, unique separation properties that enlarge the capabilities of HPLC methods have been achieved, such as ultrahigh-pressure liquid chromatography based on sub-2μm silica particles, fast liquid chromatography based on superficially porous silica particles, high temperature liquid chromatography based on organic/silica hybrid particles. Moreover, novel stationary phase can be obtained by chemical bonding or polymer modification of silica surface, such as chiral stationary phase, temperature-responsive stationary phase and restricted access materials. In this paper, the preparation methods and modification modes of silica particles are introduced, as well as the characterization methods of HPLC stationary phase. The applications of silica packing material in HPLC and its developing trends are also outlined. Source

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