@article {1491, title = {Analysis of amphetamine, methamphetamine and methylenedioxy-methamphetamine by micellar capillary electrophoresis using cation-selective exhaustive injection}, journal = {Electrophoresis}, volume = {27}, number = {16}, year = {2006}, note = {ISI Document Delivery No.: 081RBTimes Cited: 18Cited Reference Count: 40Meng, Pinjia Fang, Ning Wang, Meng Liu, Huwei Chen, David D. Y.}, month = {Aug}, pages = {3210-3217}, type = {Article}, abstract = {Cation-selective exhaustive injection (CSEI) is used as an on-line concentration method for the high-sensitivity analysis of illicit amphetamines using CE. Optimum conditions for the determination of amphetamine, methamphetamine and methylenedioxy-methamphetamine were investigated. Sodium dodecyl sulfate (25 mM) in 100 mM phosphate buffer (pH 2.9) with 20\% methanol as organic additive was used as the background electrolyte for CE separation. The LOD, based on an S/N of 3:1, was about 0.01 mu g/mL using normal capillary micellar electrokinetic chromatography, while by using CSEI in combination with micellar sweeping the sensitivity increased up to 1000-fold with the LOD lower than 50 pg/mL. The reproducibility of CSEI combined with micellar sweeping for analyzing amphetamines was satisfactory (relative standard deviation around 10\% by using area ratios against an internal standard). This method is highly sensitive and can be used to analyze trace amount amphetamines in human hair.}, keywords = {amphetamine, AMPLIFIED SAMPLE STACKING, analysis, cation-selective exhaustive injection, CHROMATOGRAPHY, CHROMATOGRAPHY-MASS SPECTROMETRY, ELECTROKINETIC, FLUORESCENCE DETECTION, illicit drug, LIQUID-CHROMATOGRAPHY, methamphetamine, methylenedioxy-methamphetamine, NEUTRAL ANALYTES, ONLINE CONCENTRATION, REVERSE MIGRATING MICELLES, SOLID-PHASE MICROEXTRACTION, ZONE-ELECTROPHORESIS}, isbn = {0173-0835}, url = {://000240333600007}, author = {Meng, P. J. and Fang, N. and Wang, M. and Liu, H. W. and Chen, D. D. Y.} } @article {397, title = {Applications of on-line weak affinity interactions in free solution capillary electrophoresis}, journal = {Electrophoresis}, volume = {23}, number = {6}, year = {2002}, note = {ISI Document Delivery No.: 536KNTimes Cited: 26Cited Reference Count: 109}, month = {Mar}, pages = {815-822}, type = {Review}, abstract = {The impressive selectivity offered by capillary electrophoresis can in some cases be further increased when ligands or additives that engage in weak affinity interactions with one or more of the separated analytes are added to the electrophoresis buffer. This on-line affinity capillary electrophoresis approach is feasible when the migration of complexed molecules is different from the migration of free molecules and when separation conditions are nondenaturing. In this review, we focus on applying weak interactions as tools to enhance the separation of closely related molecules, e.g., drug enantiomers and on using capillary electrophoresis to characterize such interactions quantitatively. We describe the equations for binding isotherms, illustrate how selectivity can be manipulated by varying the additive concentrations, and show how the methods may be used to estimate binding constants. On-line affinity capillary electrophoresis methods are especially valuable for enantiomeric separations and for functional characterization of the contents of biological samples that are only available in minute quantities.}, keywords = {affinity capillary electrophoresis, ALPHA(1)-ACID, AMYLOID-P COMPONENT, biomolecular interactions, capillary electrophoresis, CHIRAL SEPARATION, CHROMATOGRAPHY, CONSTANTS, ELECTROKINETIC, enantiomer separation, ENANTIOSELECTIVE PROTEIN, FRONTAL ANALYSIS, GLYCOPROTEIN, isotherms, MEASURE BINDING, PARTIAL-FILLING TECHNIQUE, PROTEIN-BINDING, review, separation methods, ZONE-ELECTROPHORESIS}, isbn = {0173-0835}, url = {://000174699400002}, author = {Heegaard, N. H. H. and Nissen, M. H. and Chen, D. D. Y.} } @article {4212, title = {A water-soluble tetraethylsulfonate derivative of 2-methylresorcinarene as an additive for capillary electrophoresis}, journal = {Analytical Chemistry}, volume = {70}, number = {5}, year = {1998}, note = {ISI Document Delivery No.: ZB216Times Cited: 12Cited Reference Count: 25}, month = {Mar}, pages = {907-912}, type = {Article}, abstract = {A water-soluble tetraethylsulfonate derivative of 2-methylresorcinarene (TESMR), an aromatic-based, bowl-shaped macrocycle, was used as an additive in capillary electrophoresis. Several phenol derivatives are used as analytes to demonstrate the effect of this highly charged additive, TESMR is observed to interact differently with a mixture of positional isomers and other types of phenol derivatives, A comparative study of separations with two charged additives, TESMR and sulfobutyl ether-beta-cyclodextrin (SBE-beta-CD), provided insight into the selectivity exhibited by these additives. The influence of buffer pH, ionic strength, and organic modifier content on separation and peak shape is investigated, Peak asymmetry caused by the use of highly charged additives at lower pH is minimized by the addition of small amounts of a polar aprotic organic solvent to the run buffer. The effects of mixing a charged additive with a neutral additive are also discussed.}, keywords = {AROMATIC CAVITY, CHROMATOGRAPHY, ELECTROKINETIC, ETHER-BETA-CYCLODEXTRIN, ISOMERS, macrocycles, RESOLUTION, RESORCINOL CYCLIC TETRAMER, SEPARATION, ZONE ELECTROPHORESIS}, isbn = {0003-2700}, url = {://000072448400021}, author = {Britr-McKibbin, P. and Chen, D. D. Y.} }