@article {4739,
	title = {Selective focusing of catecholamines and weakly acidic compounds by capillary electrophoresis using a dynamic pH junction},
	journal = {Analytical Chemistry},
	volume = {72},
	number = {6},
	year = {2000},
	note = {ISI Document Delivery No.: 295NRTimes Cited: 171Cited Reference Count: 43},
	month = {Mar},
	pages = {1242-1252},
	type = {Article},
	abstract = {A systematic study of selective analyte focusing in a multisection electrolyte system by capillary electrophoresis (CE) is presented. It was found that a dynamic pH junction between sample and background electrolyte zones can be used to focus zwitterionic catecholamines and weakly acidic compounds without the use of special ampholytes. Differences in pH and concentration of complexing agents, such as berate, in the sample and background electrolyte zones were determined to cause focusing through changes in the local velocity of the analyte in two different segments of the capillary. Velocity-differerence induced focusing (V-DIF) of analytes using a dynamic pH junction allowed the injection of large sample volumes and significantly improved the concentration sensitivity of CE. Under optimized conditions, the limit of detection for epinephrine was determined to be about 4 x 10(-8) M (the original sample) with conventional UV absorbance detection. Moreover, separation efficiencies greater than a million theoretical plates can be achieved by focusing such large sample volumes into narrow zones. Multisection electrolyte systems, which lead to the formation of a dynamic pH junction, can be tuned toward improving the concentration sensitivity of specific analytes their chemical properties are known.},
	keywords = {DNA-ADDUCTS, ELECTROCHEMICAL DETECTION, INJECTION, MICELLAR ELECTROKINETIC CHROMATOGRAPHY, MIGRATING MICELLES, NEUTRAL ANALYTES, REVERSE, SAMPLE SELF-STACKING, SEPARATION, VOLUME, ZONE-ELECTROPHORESIS},
	isbn = {0003-2700},
	url = {<Go to ISI>://000085975200021},
	author = {Britz-McKibbin, P. and Chen, D. D. Y.}
}
@article {4738,
	title = {Velocity-difference induced focusing of nucleotides in capillary electrophoresis with a dynamic pH junction},
	journal = {Analytical Chemistry},
	volume = {72},
	number = {8},
	year = {2000},
	note = {ISI Document Delivery No.: 304RDTimes Cited: 122Cited Reference Count: 35},
	month = {Apr},
	pages = {1729-1735},
	type = {Article},
	abstract = {Velocity-difference induced focusing (V-DIF) of nucleotides was achieved by using a dynamic pH junction in capillary electrophoresis (CE) with UV detection. The influence of specific analyte properties, such as nucleotide base structure, sugar structure, and degree of phosphorylation, is examined. The pK(a) values and berate complexation with vicinal diols are important factors that caused the focusing. Therefore, the pH and berate content in the sample and background electrolyte can be adjusted to optimize the focusing effect. This method allows the injection of large volumes of sample (similar to 300 nL), resulting in at least 50-fold improvement in concentration sensitivity. The detection limit of 4.0 x 10(-8) M for nucleotides can be achieved in favorable conditions. V-DIF can be also applied to nucleotide pool analysis from cell extracts to improve the concentration sensitivity of CE and to reduce the time-consuming steps of desalting and off-line preconcentration that are often required for assays of nucleotides from biological samples.},
	keywords = {DNA-ADDUCTS, ELECTROPHORESIS, INJECTION, ISOTACHOPHORESIS, MICELLAR ELECTROKINETIC CHROMATOGRAPHY, NEUTRAL ANALYTES, SAMPLE SELF-STACKING, SEPARATION, TRIPHOSPHATES, VOLUME, ZONE},
	isbn = {0003-2700},
	url = {<Go to ISI>://000086497200001},
	author = {Britz-McKibbin, P. and Bebault, G. M. and Chen, D. D. Y.}
}
