Contactless conductivity detection for capillary electrophoresis: Hardware improvements and optimization of the input-signal amplitude and frequency

• Published in: Journal of Chromatography A Vol. 942; no. 1; pp. 249 - 258
• Main Authors: Fracassi da Silva, José A, Guzman, Norberto, do Lago, Claudimir L
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 04-01-2002; Elsevier
• Subjects: Analytical chemistry; Chemistry; Chromatographic methods and physical methods associated with chromatography; Electrochemistry - instrumentation; Electrochemistry - methods; Electrophoresis, Capillary - methods; Exact sciences and technology; Metal cations; Other chromatographic methods; Detection, electrophoresis; Instrumentation; Metal cations; Conductivity detection; Barium Ions; Sodium Ions; Zone electrophoresis; Capillary electrophoresis; Experimental study; Potassium Ions; Optimization; Alkaline earth metal Ions; Electrochemical detector; Inorganic cation; Conductometry; Alkali metal Ions; Detection
• ISSN: 0021-9673
• DOI: 10.1016/S0021-9673(01)01380-2

A new prototype of contactless conductivity detector, smaller and easier to operate than the former version, is described. For a fused-silica capillary with 142-μm wall thickness and voltages up to 25 kV, it can be placed at the low- or high-voltage end of the column. This feature allowed implementation of an apparatus with sample introduction at the grounded end of the column. The input signal is an important parameter for determining the signal-to-noise ratio (
S/
N) of the detection system. An optimization procedure of its amplitude and frequency is proposed. Although the
S/
N must be determined by introduction of actual samples, the operating conditions can be optimized merely by changing the signal parameters and by using a mathematical procedure. Thus, an easy and fast optimization routine can be carried out. Mathematical and instrumental backgrounds are discussed, and experimental support of the technique’s effectiveness is presented.