Considerations on contactless conductivity detection in capillary electrophoresis.
Nearly all analyses by capillary electrophoresis (CE) are performed using optical detection, utilizing either absorbance or (laser-induced) fluorescence. Though adequate for many analytical problems, in a large number of cases, e.g., involving non-UV-absorbing compounds, these optical detection methods fall short. Indirect optical detection can then still provide an acceptable means of detection, however, with a strongly reduced sensitivity. During the past few years, contactless conductivity detection (CCD) has been presented as a valuable extension to optical detection techniques. It has been demonstrated that with CCD detection limits comparable, or even superior, to (indirect) optical detection can be obtained. Additionally, construction of the CCD around the CE capillary is straightforward and robust operation is easily obtained. Unfortunately, in the literature a large variety of designs and operating conditions for CCD were described. In this contribution, several important parameters of CCD are identified and their influence on, e.g., detectability and peak shape is described. An optimized setup based on a well-defined detection cell with three detection electrodes is presented. Additionally, simple and commercially available read-out electronics are described. The performance of the CCD-CE system was demonstrated for the analysis of peptides. Detection limits at the microM level were obtained in combination with good peak shapes and an overall good performance and stability.
Laboratory of Analytical Biotechnology, Kluyver Institute for Biotechnology, Faculty of Applied Sciences, Delft, The Netherlands.
Erik
E
Baltussen
Rosanne M
RM
Guijt
Gert
G
van der Steen
Frederic
F
Laugere
Sander
S
Baltussen
Gijs W K
GW
van Dedem
D002021:Buffers; D004553:Electric Conductivity; D004581:Electronics; D019075:Electrophoresis, Capillary / Q000295:instrumentation* / Q000592:standards; D004867:Equipment Design; D008670:Metals / Q000302:isolation & purification; D010455:Peptides / Q000302:isolation & purification
D002021:Buffers; D008670:Metals; D010455:Peptides