The analysis of sucrose esters with long acyl chain by improved high performance liquid chromatographic method with evaporative light scattering detection （HPLC-ELSD） and electrospray ionization mass spectrum （ESI...The analysis of sucrose esters with long acyl chain by improved high performance liquid chromatographic method with evaporative light scattering detection （HPLC-ELSD） and electrospray ionization mass spectrum （ESI-MS） is investigated. The improved HPLC-ELSD method for the separation and quantitation of commercial and synthesized sucrose esters is described. Samples are analyzed by means of a reversed-phase （RP） HPLC using a Hypersil C8 column （250 mm× 4.6 mm, 5 μm particle size） with methanol-tetrahydrofuran （vo）ume ratio of 90 ： 10） and water under gradientcondition as the mobile phase, in which the flow rate is 1.0 ml·min^-1 and the column temperature is set at 40℃. This procedure provides a complete separation and determination ot monoester, diester, triester and higher esters with different acyl chain lengths in each fraction by a single run, in combination with the ESI-MS technology. With this method, it is possible to determine the approximate compositions of monoto polyesters in one analysis and quantitate pure positional isomers precisely using an external standard method. It is found that the method of ESI-MS coupling with HPLC system for the analysis of sucrose esters is straight forward, rapid and inexpensive, and can be readily applied in synthesis, purification and structure studies.展开更多
Polysiloxane latexes were prepared by microemulsion polymerization of octamethylcyclotetrasiloxane （D4） in the absence of co-emulsifier with octadecyl trimethyl ammonium chloride as a cationic emulsifier and potassi...Polysiloxane latexes were prepared by microemulsion polymerization of octamethylcyclotetrasiloxane （D4） in the absence of co-emulsifier with octadecyl trimethyl ammonium chloride as a cationic emulsifier and potassium hydrate as an initiator. The particle size was determined by the dynamic light scattering （DLS） technique and the reaction rates of the polymerization were discussed. Furthermore, the kinetics was studied by an initial-rate method, and the effects of the monomer, emulsifier and initiator concentrations and the temperature on polymerization conversions were investigated. From the kinetic results, the rate of polymerization, Rp at 80℃ can be expressed as Rp = k[D4]^0.79 [OTAC]^0.64[KOH]^0.38 and the aonarent activation energy（Ea）. which was determined by half-period method, is 95.32 kJ mol^-1.展开更多
基金Supported by the National Natural Science Foundation of China （20906052）, the Science Foundation of Nantong City Municipality （K2007011, K2008023）, the Science Foundation of Nantong University （08R08） and the University Science Research Project of Jiangsu Province （09KJB530008）.
文摘The analysis of sucrose esters with long acyl chain by improved high performance liquid chromatographic method with evaporative light scattering detection （HPLC-ELSD） and electrospray ionization mass spectrum （ESI-MS） is investigated. The improved HPLC-ELSD method for the separation and quantitation of commercial and synthesized sucrose esters is described. Samples are analyzed by means of a reversed-phase （RP） HPLC using a Hypersil C8 column （250 mm× 4.6 mm, 5 μm particle size） with methanol-tetrahydrofuran （vo）ume ratio of 90 ： 10） and water under gradientcondition as the mobile phase, in which the flow rate is 1.0 ml·min^-1 and the column temperature is set at 40℃. This procedure provides a complete separation and determination ot monoester, diester, triester and higher esters with different acyl chain lengths in each fraction by a single run, in combination with the ESI-MS technology. With this method, it is possible to determine the approximate compositions of monoto polyesters in one analysis and quantitate pure positional isomers precisely using an external standard method. It is found that the method of ESI-MS coupling with HPLC system for the analysis of sucrose esters is straight forward, rapid and inexpensive, and can be readily applied in synthesis, purification and structure studies.
文摘Polysiloxane latexes were prepared by microemulsion polymerization of octamethylcyclotetrasiloxane （D4） in the absence of co-emulsifier with octadecyl trimethyl ammonium chloride as a cationic emulsifier and potassium hydrate as an initiator. The particle size was determined by the dynamic light scattering （DLS） technique and the reaction rates of the polymerization were discussed. Furthermore, the kinetics was studied by an initial-rate method, and the effects of the monomer, emulsifier and initiator concentrations and the temperature on polymerization conversions were investigated. From the kinetic results, the rate of polymerization, Rp at 80℃ can be expressed as Rp = k[D4]^0.79 [OTAC]^0.64[KOH]^0.38 and the aonarent activation energy（Ea）. which was determined by half-period method, is 95.32 kJ mol^-1.
