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Ni X.,Jiangnan University | Zhuo X.,Jiangnan University | Xu X.,Jiangnan University | Cao Y.,Jiangnan University | And 2 more authors.
Journal of Chromatography A

The random amphiphilic polymeric aggregation, self-assembled from poly (methyl methacrylate-. co-methacrylic acid) (P(MMA-. co-MAA)), was explored as a novel pseudostationary phase (PSP) in electrokinetic chromatography (EKC) in our previous report. This work focused on physicochemical characteristics and PSP performances of the polymeric aggregations. The physicochemical characteristics of polymeric aggregations, including critical aggregation concentration (CAC), zeta potential, hydrodynamic diameter, and micropolarity were determined. Experimental results showed that polymeric aggregations had much lower CAC, which decreased the usage of copolymer in EKC, weakened ionic strength and shortened analysis time. The monomer molar ratio of the copolymer was a key factor for physicochemical characteristics and PSP performances of the polymeric aggregations. With the increase of the hydrophobic monomer molar ratio, CAC, micropolarity and dimension of polymeric aggregation decreased significantly while zeta potentials were similar. Correspondingly, separation window enlarged and methylene selectivity evaluated with six kinds of n-alkylphenone homologous series enhanced. Linear solvation energy relationships (LSER) analysis found that hydrophobic interaction is the most important interaction between analytes and polymeric PSPs. Compared with SDS micelle, polymeric aggregations owned more types of interactions, such as stronger hydrogen bonding and relative larger dipole interaction, which provided a bigger adjustment room to improve PSP selectivity. © 2014 Elsevier B.V. Source

Ni X.,Jiangnan University | Yu M.,Jiangnan University | Cao Y.,Jiangnan University | Cao Y.,The Key Laboratory of Food Colloids and Biotechnology | Cao G.,Jiangnan University

In this work, the influences of ionic liquid (IL) as a modifier on microemulsion microstructure and separation performance in MEEKC were investigated. Experimental results showed that synergetic effect between IL 1-butyl-3-methylimidazolium tetrafluoro-borate (BmimBF4) and surfactant SDS gave a decreased CMC. With increment of IL in microemulsion, negative ζ potential of the microdroplets reduced gradually. The influence of IL on the dimensions of microdroplet was complicated. At BmimBF4 less than 8 mM, IL made microemulsion droplet smaller in size. While at BmimBF4 more than 10 mM, the size increased and reached to a maximum value at 12 mM, where the microdroplets were larger than that without IL. After that, the micreodroplet size decreased again. Relative fluorescence intensity of the first vibration band of pyrene to the third one (I1/I3) enhanced as IL was added to microemulsion, which indicated that this addition increased environmental polarity in the inner core of microdroplets. Prednisone, hydrocortisone, prednisolone, hydrocortisone acetate, cortisone acetate, prednisolone acetate, and triamcinolone acetonide were analyzed with MEEKC modified with IL to evaluate the separation performance. Cortisone acetate and prednisolone acetate could not be separated at all in typical microemulsion. The seven analytes could be separated by the addition of 10 mM BmimBF4 into the microemulsion system. The method has been used for analysis of corticosteroids in cosmetic samples with simple extraction; the recoveries for seven analytes were between 86 and 114%. This method provides accuracy, reproducibility, pretreatment simplicity, and could be applied to the quality control of cosmetics. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

Huang Y.-J.,Jiangnan University | Zhou X.-Y.,Jiangnan University | Li Z.-J.,Jiangnan University | Li Z.-J.,The Key Laboratory of Food Colloids and Biotechnology | And 2 more authors.
Chinese Journal of Inorganic Chemistry

Different anionic surfactant was empolyed as additive for the seed-mediated synthesis of gold nanorods and effect of the kind of anionic surfactant on the morphology and optical property of gold nanorods were also investigated. In the presence of sodium dodecyl benzene sulfonate (SDBS), the yield of gold nanorods is obviously higher that of the reaction system using sodium dodecyl sulfate. The reaction conditions of the seed-mediated synthesis of gold nanorods added SDBS were optimized, and the optimal concentrations of hexadecyltrimethylammonium bromide, SDBS, ascorbic acid and silver nitrate were found to be 0.04 mol·L-1, 2.4 mmol·L-1, 1.2 mmol·L-1 and 0.08 mmol·L-1, respectively. Under the condition, the growth of gold nanorods can complete within 30 minutes, the as-prepared gold nanorods offer a surface plasmon resonance absorption with a maximum absorption peak at 823 nm and aspect ratio of (5±0.03). When changing silver nitrate concentration in the growth solution, the size of gold nanorods also changed. In addition, we also discussed the action mechanism of SDBS. In comparsion with classical seed-mediated synthesis method, proposed method for synthesis of gold nanorods shows an obvious improvement of size adjustable, monodispersity and biological toxicity, and it can be widely applied to a variety of optical and biological analysis. Source

Chen T.-Y.,Jiangnan University | Zhang C.-J.,Jiangnan University | Li Z.-J.,Jiangnan University | Li Z.-J.,The Key Laboratory of Food Colloids and Biotechnology | Gu Z.-G.,Jiangnan University
Chinese Journal of Inorganic Chemistry

Tetrabutyl titanate and graphite oxide were dispersed in tertbutanol by ullrasonicalion and then added the lithium acetate solution into the above mixed solution under the microwave radiation to produce spinel Li4Ti5O12 (LTO) precursor/graphene oxide. On the one hand, the microwave radiation will promote the hydrolysis of tetrabutyl titanate, thus the reaction for forming the precursor can be completed in 15 min. On the other hand, “soft template” confinement effect of tertbutanol leads to form the LTO precursor with very small particle size and uniform morphology. Meanwhile, small LTO precursor particles will fully embed the graphene oxide nanosheets through their second agglomeration. Finally, the LTO precursor/graphene oxide was calcined at 800 °С for 8 h to obtain spinel LTO@graphene (LTO@G). The study shows that LTO crystal in the LTO@G has a diameter of 0.2~1.5 μm and the tap density of LTO@G reached 1.7 g·cm-3. The graphene is located inside the crystal and significantly improve the electronic conductivity. The conductivity of LTO@G was found to be 1.84× 10-3 S·m-1, which is remarkably higher than pure phase LTO (1.1 ×10-7 S·m-1). In 1C and 4C, the first discharge specific capacitances of LTO@G was found to be 170.1 mAh·g-1 and 97.5 mAh·g-1, respectively. These results demonstrated that the LTO@G has good high-rate capability and tap density, it can be widely used in various commercial lithium ion battery. © 2014, Chinese Chemical Society, All rights reserved. Source

Lu J.,Jiangnan University | Ni X.,Jiangnan University | Cao Y.,Jiangnan University | Cao Y.,The Key Laboratory of Food Colloids and Biotechnology | And 2 more authors.

A novel catanionic surfactants vesicle system composed of octyltriethylammonium bromide/ sodium dodecyl benzene sulfonate (C8NE3Br/SDBS) has been developed as pseudostationary phase (PSP) in EKC. The C8NE3Br/SDBS system possesses a large vesicle phase region and none of agglomeration phenomena appeared while mixing cationic and anionic surfactants at any molar ratio. Electrophoretic and chromatographic parameters including elution window, hydrophobic selectivity, polar group selectivity, and shape selectivity were characterized using the vesicle at molar ratio of C8NE3Br to SDBS of 3:7 as PSP. Compared with SDS micelles, the vesicle PSP possessed a wider elution window and a better selectivity. The retention behavior and selectivity differences between the novel vesicle and SDS micelles were evaluated through linear solvation energy relationship (LSER) analysis. Though the cohesiveness and the hydrogen bond acidity have greatest influences on the solutes retention and selectivity in both the vesicle and SDS micelle, the vesicle PSP demonstrated a higher hydrophobicity and a lower hydrogen bonding donating capability owing to compact bilayer structure of vesicle. Additionally, the vesicle system had a stronger hydrogen bond accepting capability than SDS micelle. Consequently, according to LSER analysis, the bigger coefficients for v, b, and a revealed the vesicle PSP had a better separation selectivity than conventional SDS micelle. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

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