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Nonaqueous capillary electrophoresis : = Investigation of efficiency and laser-induced fluorescence detection limits.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Nonaqueous capillary electrophoresis :/
Reminder of title:	Investigation of efficiency and laser-induced fluorescence detection limits.
Author:	Ward, Vicki Lynn.
Description:	1 online resource (160 pages)
Notes:	Source: Dissertations Abstracts International, Volume: 60-12, Section: B.
Contained By:	Dissertations Abstracts International60-12B.
Subject:	Analytical chemistry. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=9922711click for full text (PQDT)
ISBN:	9780599222779

Nonaqueous capillary electrophoresis : = Investigation of efficiency and laser-induced fluorescence detection limits.
Ward, Vicki Lynn.

Nonaqueous capillary electrophoresis :Investigation of efficiency and laser-induced fluorescence detection limits. - 1 online resource (160 pages)

Source: Dissertations Abstracts International, Volume: 60-12, Section: B.

Thesis (Ph.D.)--North Carolina State University, 1998.

Includes bibliographical references

Comparative studies of laser induced fluorescence detection (LIF) limits and efficiency were performed in nonaqueous and aqueous capillary electrophoresis (CE). First, LIF detection limits of ANTS-derivatized maltooligosaccharides were determined in aqueous and nonaqueous citric acid buffers prepared in formamide, N-methylformamide, and milli-Q water. Aqueous buffers treated with purge and freeze-pump-thaw degassing were also examined. Degassing of the aqueous buffer showed no effect on the detection limit when compared to untreated aqueous buffer. Steady state fluorescence revealed that the fluorescence was being quenched by the buffer itself. Both nonaqueous solvents provided a 2-fold enhancement in the LIF-CE detection limit of the oligosaccharides over that of aqueous CE. Additionally, a 5 and 6-fold enhancement in the steady state fluorescence signal was observed in the absence of citric acid buffer for formamide and N-methylformamide, respectively. The lower detection limits achieved in the nonaqueous media were attributed to a combination of the viscosity and polarity of the medium, both of which can influence quenching. Secondly, the efficiency of ANTS-derivatized maltooligosaccharides and several band broadening mechanisms were evaluated in both aqueous and nonaqueous CE. The injection volume, applied voltage, and buffer concentration were optimized to minimize band broadening effects of over injection, Joule heating, and electrophoretic dispersion. At the optimized conditions, the nonaqueous medium (formamide) produced a 1.5-fold enhancement in the efficiency of the oligosaccharides over that in the aqueous buffer medium. The oligosaccharides were also discovered to be experiencing wall interactions which in turn decrease efficiency. The overall higher efficiencies of the nonaqueous CE were attributed to the generation of less Joule heat and the potential of stacking by the formamide buffer medium. Thirdly, viscosity studies performed in aqueous CE demonstrated that efficiencies comparable to those in the nonaqueous media can be achieved. Increased viscosity of the aqueous buffer medium results in less Joule heating and possible stacking.

Electronic reproduction.
Ann Arbor, Mich. :
ProQuest,
2023

Mode of access: World Wide Web

ISBN: 9780599222779Subjects--Topical Terms:

3168300
Analytical chemistry.
Subjects--Index Terms:

Capillary electrophoresisIndex Terms--Genre/Form:

542853
Electronic books.

Nonaqueous capillary electrophoresis : = Investigation of efficiency and laser-induced fluorescence detection limits.
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245 1 0 $a Nonaqueous capillary electrophoresis : $b Investigation of efficiency and laser-induced fluorescence detection limits.
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300 $a 1 online resource (160 pages)
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500 $a Source: Dissertations Abstracts International, Volume: 60-12, Section: B.
500 $a Publisher info.: Dissertation/Thesis.
500 $a Advisor: Khaledi, Morteza G.
502 $a Thesis (Ph.D.)--North Carolina State University, 1998.
504 $a Includes bibliographical references
520 $a Comparative studies of laser induced fluorescence detection (LIF) limits and efficiency were performed in nonaqueous and aqueous capillary electrophoresis (CE). First, LIF detection limits of ANTS-derivatized maltooligosaccharides were determined in aqueous and nonaqueous citric acid buffers prepared in formamide, N-methylformamide, and milli-Q water. Aqueous buffers treated with purge and freeze-pump-thaw degassing were also examined. Degassing of the aqueous buffer showed no effect on the detection limit when compared to untreated aqueous buffer. Steady state fluorescence revealed that the fluorescence was being quenched by the buffer itself. Both nonaqueous solvents provided a 2-fold enhancement in the LIF-CE detection limit of the oligosaccharides over that of aqueous CE. Additionally, a 5 and 6-fold enhancement in the steady state fluorescence signal was observed in the absence of citric acid buffer for formamide and N-methylformamide, respectively. The lower detection limits achieved in the nonaqueous media were attributed to a combination of the viscosity and polarity of the medium, both of which can influence quenching. Secondly, the efficiency of ANTS-derivatized maltooligosaccharides and several band broadening mechanisms were evaluated in both aqueous and nonaqueous CE. The injection volume, applied voltage, and buffer concentration were optimized to minimize band broadening effects of over injection, Joule heating, and electrophoretic dispersion. At the optimized conditions, the nonaqueous medium (formamide) produced a 1.5-fold enhancement in the efficiency of the oligosaccharides over that in the aqueous buffer medium. The oligosaccharides were also discovered to be experiencing wall interactions which in turn decrease efficiency. The overall higher efficiencies of the nonaqueous CE were attributed to the generation of less Joule heat and the potential of stacking by the formamide buffer medium. Thirdly, viscosity studies performed in aqueous CE demonstrated that efficiencies comparable to those in the nonaqueous media can be achieved. Increased viscosity of the aqueous buffer medium results in less Joule heating and possible stacking.
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538 $a Mode of access: World Wide Web
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653 $a Capillary electrophoresis
653 $a Citric acid buffers
653 $a Detection limits
653 $a Fluorescence
653 $a Formamides
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710 2 $a North Carolina State University. $3 1018772
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856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=9922711 $z click for full text (PQDT)