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Application of the Phenomenological Model to Electrophoretic Mobility in Mixed Solvent Electrolyte Systems in Capillary Zone Electrophoresis
Abolghasem Jouyban,Hak-Kim Chan,Maryam Khoubnasabjafari
Iranian Journal of Pharmaceutical Research , 2004,
Abstract: The phenomenological model of Khossravi and Connors (1992) has been adopted to calculate the electrophoretic mobility of drugs at different concentrations of solvents in a binary mixture. The accuracy and predictability of the model have been evaluated employing 14 experimental data sets by using average percentage mean deviation (APMD). The obtained APMD for correlative and predictive studies are within an acceptable error range and the results show that the model can be used in method development stage to speed up the optimisation process.
Analysis of Chiral Compounds by Micelle Electrokinetic Capillary Chromatography

Y He,M Zheng,W Gan,

色谱 , 1999,
Abstract: An overview on applications of micelle electrokinetic capillary chromatography(MECC) in chiral compounds analysis is presented. Ionic chiral surfactants such as bile salts, long alkyl chain surfactants and high molecular weight surfactants, which can migrate with electroosmosis and its electrophoretic mobility, and interact with the solutes, are employed as chiral selectors. Addition of electrically neutral chiral selectors such as cyclodextrins is also successful in MECC separation. Theory of MECC enantiomer separation is briefly described.
Mathematical representation of electrophoretic mobility in ternary solvent electrolyte systems
"Jouyban A,Chan HK,Khoubnasab Jafari M,Clark BJ "
DARU : Journal of Pharmaceutical Sciences , 2002,
Abstract: Electrophoretic mobilities of salmeterol and phenylpropanolamine in capillary zone electrophoresis were determined using acetate buffer in mixed solvents containing different concentrations of water, methanol and acetonitrile. Maximum electrophoretic mobilities for salmeterol and phenylpropanolamine were observed with water-methanol-acetonitrile ratios of 5:50:45 v/v and 3:60:37 v/v, respectively, and minimum mobilities of both compounds occurred in methanol-acetonitrile ratio of 30:70 v/v. The generated experimental data have been used to evaluate a mathematical model to compute the electrophoretic mobility of the analytes in a ternary solvent electrolyte system. The proposed model is: ln μm = 1 ln μ1+ 2 ln μ2+k 3+M1 1 2+M2 1 3+M3 2 3+M4 1 21+M5 22 3+M6 22 3+M7 1 2 3. Where μ is the electrophoretic mobility, subscripts m,1, 2 and 3 refer to mixed solvent and solvents 1-3, respectively, f is the volume fraction of the solvent in the mixed solvent system and M1-M7 and K are the model constants calculated by a least squares analysis. The generated experimental data fitted to the model and the back-calculated mobilities were employed to compute the average percentage deviation (APD) as an accuracy criterion. The obtained APD for salmeterol and phenylpropanolamine are 3.10 and 2.21%, respectively and the low APD values indicate that the model is able to calculate the mobilities within an acceptable error range.
Numerical Analysis on the Influence Factors of Sample Stacking in Capillary Electrophoresis

CAO Jun,HONG Fangjun,CHENG Ping,

色谱 , 2007,
Abstract: Sample stacking in capillary electrophoresis can concentrate sample species through the electrical field strength gradient caused by the inhomogeneous buffer concentration field in capillary. The factors that affect the sample stacking process have been analyzed in detail by using a 1-D mathematic model. It was found from the simulation results that the electrical charge number and the electrical charge sign of sample particles can affect the electrophoretic velocity, which in turn has an important influence on the stacking process. The electrical potential can affect the migration time of sample particles to reach detection window, and the initial length of sample plug has significant influence on the maximal sample concentration after stacking and the time to get the optimal stacking effect. The results obtained are helpful to the improvement of the sample stacking technique.
Solvent-induced micelle formation in a hydrophobic interaction model  [PDF]
S. Moelbert,B. Normand,P. De Los Rios
Physics , 2003, DOI: 10.1103/PhysRevE.69.061924
Abstract: We investigate the aggregation of amphiphilic molecules by adapting the two-state Muller-Lee-Graziano model for water, in which a solvent-induced hydrophobic interaction is included implicitly. We study the formation of various types of micelle as a function of the distribution of hydrophobic regions at the molecular surface. Successive substitution of non-polar surfaces by polar ones demonstrates the influence of hydrophobicity on the upper and lower critical solution temperatures. Aggregates of lipid molecules, described by a refinement of the model in which a hydrophobic tail of variable length interacts with different numbers of water molecules, are stabilized as the length of the tail increases. We demonstrate that the essential features of micelle formation are primarily solvent-induced, and are explained within a model which focuses only on the alteration of water structure in the vicinity of the hydrophobic surface regions of amphiphiles in solution.
Transient electrophoretic current in a nonpolar solvent  [PDF]
Pavel Kornilovitch,Yoocharn Jeon
Physics , 2011, DOI: 10.1063/1.3554445
Abstract: The transient electric current of surfactants dissolved in a nonpolar solvent is investigated both experimentally and theoretically in the parallel-plate geometry. Due to a low concentration of free charges the cell can be completely polarized by an external voltage of several volts. In this state, all the charged micelles are compacted against the electrodes. After the voltage is set to zero the reverse current features a sharp discharge spike and a broad peak. This shape and its variation with the compacting voltage are reproduced in a one-dimensional drift-diffusion model. The model reveals the broad peak is formed by a competition between an increasing number of charges drifting back to the middle of the cell and a decreasing electric field that drives the motion. After complete polarization is achieved, the shape of the peak stops evolving with further increase of the compacting voltage. The spike-peak separation time grows logarithmically with the charge content in the bulk. The time peak is a useful measure of the micelle mobility. Time integration of the peak yields the total charge in the system. By measuring its variation with temperature, the activation energy of bulk charge generation has been found to be 0.126 eV.
Electrophoretic Mobility and Size Determination of Aerosol OT Inverse Micelle in Decane Using Phase Analysis Light Scattering (PALS) and Dynamic Light Scattering (DLS) Respectively  [PDF]
International Journal of Applied Physics and Mathematics , 2013, DOI: 10.7763/ijapm.2013.v3.182
Abstract: Aerosol OT is a well known surfactant used as negative charging agent. When dissolved in a solvent an Aerosol OT molecule is ionized to become negatively charged head group (RSO-3) and a positively charged sodium ion (Na+). The head groups are supposed to adsorb onto the surface of dispersed particles leaving positively charged counter-ions in the solution. However, silica particles are positively charged when suspended in the dispersion of Aerosol OT in decane. Only at concentrations below approximately 0.5mM the data showed that silica particles are negatively charged.In searching for strong evidences supporting the above fact, inverse micelles of Aerosol OT in decane were observed in term of their charge and size growth using Phase Analysis Light Scattering (PALS) and Dynamic Light Scattering (DLS) respectively. The results showed that inverse micelles of Aerosol OT in decane were negatively charged. This evidence strongly support that the positive ions adsorb onto the particle to impart positive charge. Further measurement on electrophoretic mobility of silica particles in the system show that at Aerosol OT concentrations 100mM-1000mM silica particles are positively charged. The negativity of Aerosol OT inverse micelle in decane is growing along with the growth of the size of micelles and the growth of Aerosol OT inverse micelles was aboserved at Aerosol OT concentration 100-1000mM
Effect of solvent composition on the critical micelle concentration of sodium deoxycholate in ethanol-water mixed solvent media  [PDF]
Ajaya Bhattarai,Sujit Kumar Shah,Ashok Kumar Yadav,Janak Adhikari
BIBECHANA , 2013, DOI: 10.3126/bibechana.v9i0.7176
Abstract: The precise measurement of the specific conductivity of sodium deoxycholate in pure water and ethanolwater mixed solvent media containing 0.10 and 0.20 volume fraction of ethanol at 303.15 K are reported. The concentration were varied from ~ 0.01 mol L-1 to ~ 0.0002 mol L-1.The conductivity of sodium deoxycholate decreases with the increase in the volume fraction of ethanol. The critical micelle concentration of sodium deoxycholate increases with the increase in the volume fraction of ethanol.
Separation of Phthalates in Non-Aqueous Micelle Using Capillary Electrokinetic Chromatography

HUANG Rui,MU Xiaojing,YIN Yongguang,WEI Weili,CHEN Zhitao,XIA Zhining,
黄 锐

色谱 , 2006,
Abstract: On the basis of non-aqueous capillary electrophoresis(NACE) and micellar electrokinetic chromatography(MEKC),a novel technique,non-aqueous micellar electrokinetic chromatography(NAMEKC),has been established.NAMEKC has the advantages of NACE and(uses) the separation mechanism of MEKC,showing special advantages for separation of hydrophobic compounds.Separation of three of the priority pollutants by U.S.Environmental Protection Agency(EPA),i.e.dimethyl phthalate(DMP),diethyl phthalate(DEP),and dibutyl phthalate(DBP),were realized in 15 min.Important factors on separation,such as the(amount) of water added in the electrophoretic running buffer,the acidity of water phase,the(organic) additive,and the concentration of sodium dodecyl sulfate(SDS),were investigated.The proportion of water in the electrophoretic running buffer could affect the current and the stability of SDS micelle.Organic additives and the acidity of water phase showed no effect on increasing resolution.The concentration of SDS was a dominant factor,affecting the partition of analytes in micelle.DMP, DEP,and DBP were separated in a short time under the optimized operation conditions using 20 mmol/L NaH_2PO_4 and 120 mmol/L SDS in formamide/water(9/1,v/v).The application of NAMEKC leads to successful separation of the three typical hydrophobic compounds,which provides a novel means to separate and analyze hydrophobic compounds.
Joule heating effects in capillary electrophoresis - designing electrophoretic microchips  [PDF]
D. Witkowski,J. ?ysko,A. Karczemska
Journal of Achievements in Materials and Manufacturing Engineering , 2009,
Abstract: Purpose: Computer simulations are widely used for designing, which contributes to a cheaper equipment developing process. In the last years computer simulations have begun to be also applied in different instances of microfluidics, especially in microchip electrophoresis (where an electrophoresis process takes place in the microcapillaries manufactured on the surface of the small plate) which is interesting for us. However, there are no many commercial programs enabling simulations of microfluidics. The programs existing in the market are recently developed as microscale brings new possibilities but also unpredictable effects and challenging problems. The aim of this paper is to develop a mature technique helpful in designing electrophoretic microchips [1-4].Design/methodology/approach: Temperature distributions occurring during capillary electrophoresis because of Joule heating effects will be calculated with use of the CoventorWare software.Findings: Computer simulations with the model of capillary, with the same geometry as the real one, are presented. Numerical simulation results are compared with the real data from the capillary electrophoresis process.Practical implications: This is the first step to create a reliable tool for designing microfluidic devices.Originality/value: This comparison shows an ability of the CoventorWare software to design electrophoretic microchips.
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