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On-line chromatographic pretreatment of samples with varying salt concentrations for capillary electrophoresis (1997)

Veraart, J. R. ; Gooijer, C. ; Lingeman, H. ; [et al.]

Springer

Chromatographia 44 (1997), S. 581-588

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ISSN: 1612-1112

Keywords: Capillary electrophoresis ; On-line LC-CE ; Sample pretreatment ; Matrix effects ; Benzoic acids

Source: Springer Online Journal Archives 1860-2000

Topics: Chemistry and Pharmacology

Notes: Summary Various methods are currently under investigation to improve concentration detection limits in capillary electrophoresis (CE). Stacking and isotachophoresis coupled in-line with free-solution electrophoresis are the techniques most frequently used. Samples containing a high and/or varying salt concentration, such as urine and serum, are difficult to handle: usually a significant loss in electrophoretic efficiency is observed compared with samples possessing a low electric conductivity. In the present paper an alternative approach is developed, i.e. a liquid chromatographic (LC)-type of sample pretreatment is coupled on-line with CE. To demonstrate the feasibility of this approach, the separation of three model compounds (benzoates) in water containing up to 400 mM of sodium chloride is studied using a 50 mM borate CE buffer of pH 9.5. The direct injection of samples with high salt concentrations in CE results in peak splitting and/or serious band broadening. These problems are not encountered when using the present LC-CE system. In addition, the detection limits are hardly influenced by the salt concentration of the sample; this underlines the robustness of the system.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF02466659

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On the mechanism of peroxyoxalate chemiluminescence. Quenched chemiluminescence as a detection method in HPLC (1989)

Gooijer, C. ; van Zoonen, P. ; Velthorst, N. H. ; [et al.]

New York : Wiley-Blackwell

Journal of Bioluminescence and Chemiluminescence 4 (1989), S. 479-483

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ISSN: 0884-3996

Keywords: Quenched CL ; peroxyoxalate ; mechanism ; detection ; HPLC ; Chemistry ; Biochemistry and Biotechnology

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Biology , Chemistry and Pharmacology

Notes: Several analytes such as the inorganic anions bromide, iodide, sulphite and nitrite and organic compounds as substituted anilines and sulphur compounds cause quenching of peroxyoxalate chemiluminescence. A detection method for liquid chromatography based on the quenching phenomenon has been developed. It makes use of an immobilized luminophore, i.e. 3-aminofluoranthene covalently bound via an alkyl-spacer on controlled pore glass, packed in the detector cell.The mechanism behind the quenching has been elucidated by investigating the roles of luminophores (both in the liquid and in solid state) and oxalates in peroxylate CL with respect to quenchers. Most probably the quencher destroys the radical ion pair produced after electron transfer in the last stage of the CIEEL reaction scheme, thus preventing the formation of electronically excited luminophore.

Additional Material: 2 Ill.