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Title: Modulation in capillary electrophoresis and analysis of DNA

Abstract

Analyte velocity modulation results when a sinusoidal AC voltage is superimposed onto the driving DC voltage. The principal motivation for the work has been exploration of voltage modulation as a technique is especially effective with excess noise limited detectors such as the refractive index detector. One advantage of an electrical modulation technique, over an optical one, is its applicability to all detection schemes. The mathematical theory of analyte velocity modulation is presented in this work. The main idea is that the superimposed AC field forces the electroosmotic flow profile to oscillate between laminar and plug flow at the modulation frequency. The changing profile induces a radial movement of sample species to and from the capillary surface. The induced sample concentration gradients can be monitored by carefully probing the capillary surface. The resulting signal is a derivative of the normal shaped peak. Derivative shaped peaks can be observed with cations, but not with anions. Anions are unable to approach the double layer region and therefore are unaffected by the modulation process. The results indicate that the double layer thickness in free solution capillary electrophoresis might be larger than the nominally calculated 3 nm. Analyte velocity modulation can be used as amore » variation of pulsed field electrophoresis in gel-filled capillaries. This technique provides superior resolution of DNA fragments and shortens their migration times. The authors demonstrate subpicogram detection limits for nucleic acids, with very high efficiencies. Theoretical plate numbers are in the range of 10[sup 5] to 10[sup 6]. They also demonstrate that sine wave modulation gives resolution similar to square wave modulation for frequencies between 10 and 100 Hz. Although a square wave contains high frequency harmonics, the authors show that in general its coupling to DNA motions is not always inferior to that of a sine wave.« less

Authors:
Publication Date:
Research Org.:
Michigan Univ., Ann Arbor, MI (United States)
OSTI Identifier:
5720798
Resource Type:
Miscellaneous
Resource Relation:
Other Information: Thesis (Ph.D.)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; DNA; ELECTROPHORESIS; ALTERNATING CURRENT; DIRECT CURRENT; IONS; MATHEMATICAL MODELS; MODULATION; REFRACTIVE INDEX; CHARGED PARTICLES; CURRENTS; ELECTRIC CURRENTS; NUCLEIC ACIDS; OPTICAL PROPERTIES; ORGANIC COMPOUNDS; PHYSICAL PROPERTIES; 400105* - Separation Procedures

Citation Formats

Demana, T. Modulation in capillary electrophoresis and analysis of DNA. United States: N. p., 1992. Web.
Demana, T. Modulation in capillary electrophoresis and analysis of DNA. United States.
Demana, T. Wed . "Modulation in capillary electrophoresis and analysis of DNA". United States.
@article{osti_5720798,
title = {Modulation in capillary electrophoresis and analysis of DNA},
author = {Demana, T},
abstractNote = {Analyte velocity modulation results when a sinusoidal AC voltage is superimposed onto the driving DC voltage. The principal motivation for the work has been exploration of voltage modulation as a technique is especially effective with excess noise limited detectors such as the refractive index detector. One advantage of an electrical modulation technique, over an optical one, is its applicability to all detection schemes. The mathematical theory of analyte velocity modulation is presented in this work. The main idea is that the superimposed AC field forces the electroosmotic flow profile to oscillate between laminar and plug flow at the modulation frequency. The changing profile induces a radial movement of sample species to and from the capillary surface. The induced sample concentration gradients can be monitored by carefully probing the capillary surface. The resulting signal is a derivative of the normal shaped peak. Derivative shaped peaks can be observed with cations, but not with anions. Anions are unable to approach the double layer region and therefore are unaffected by the modulation process. The results indicate that the double layer thickness in free solution capillary electrophoresis might be larger than the nominally calculated 3 nm. Analyte velocity modulation can be used as a variation of pulsed field electrophoresis in gel-filled capillaries. This technique provides superior resolution of DNA fragments and shortens their migration times. The authors demonstrate subpicogram detection limits for nucleic acids, with very high efficiencies. Theoretical plate numbers are in the range of 10[sup 5] to 10[sup 6]. They also demonstrate that sine wave modulation gives resolution similar to square wave modulation for frequencies between 10 and 100 Hz. Although a square wave contains high frequency harmonics, the authors show that in general its coupling to DNA motions is not always inferior to that of a sine wave.},
doi = {},
url = {https://www.osti.gov/biblio/5720798}, journal = {},
number = ,
volume = ,
place = {United States},
year = {1992},
month = {1}
}

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