Contactless Conductivity Detection for Capillary Electrophoresis

Zemann, Andreas; Schnell, E.; Volgger, Dietmar; Bonn, Günther K.

doi:10.1021/ac9707592

Cited by 511 publications

(421 citation statements)

References 34 publications

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“…It can be attributed to the complicated equivalence circuit of the detection cell 10 ' n and/or to changes in the dielectric properties of the solvent. 12 All subsequent work employed a frequency of 200 kHz which offered the most favorable response characteristics.…”

Section: Resultsmentioning

confidence: 99%

A chip-based capillary electrophoresis-contactless conductivity microsystem for fast measurements of low-explosive ionic components

Wang

Pumera

Collins

et al. 2002

Analyst

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A miniaturized analytical system for separating and detecting inorganic explosive residues, based on the coupling of a micromachined capillary electrophoresis (CE) chip with a contactless conductivity detector is described. The low electroosmotic flow (EOF) of the poly(methylmethacrylate) (PMMA) chip material facilitates the rapid switching between analyses of cations and anions using the same microchannel and run buffer (and without an EOF modifier), and hence offers rapid ( < 1 min) measurement of seven explosive-related cations and anions. Experimental parameters relevant to the separation and detection processes have been optimized. Addition of a 18-crown-6 ether modifier has been used for separating the peaks of co-migrating potassium and ammonium ions. The ionic-explosive microchip system combines the distinct advantages of contactless conductivity detection with the attractive features of plastic CE microchips. The new microsystem offers great promise for monitoring explosive-related ions at the sample source, with significant advantages of speed/warning, efficiency, cost, or sample size.

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Section: Resultsmentioning

confidence: 99%

A chip-based capillary electrophoresis-contactless conductivity microsystem for fast measurements of low-explosive ionic components

Wang

Pumera

Collins

et al. 2002

Analyst

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“…However, C 4 D can be recorded along the entire length of a column non-invasively, with the recorded response directly proportional to the sum of conducting elements within the , virtual electrode area' [22][23][24][25][26][27]. The presence of non-conducting monolithic phase filled with a background solution, housed within a fused silica capillary of uniform character, will provide a conductive response proportional to the fluid volume.…”

Section: Cross-validation Of the C 4 D Methodologymentioning

confidence: 99%

“…The principles of C 4 D have been well studied [22][23][24][25][26][27], and the electronic circuitry has been found to be simple and of low cost. The advantage of C 4 D over conventional conductivity detection for chromatography is that the cell design is extremely robust and there is a lack of physical contact with the eluent.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of photografted charged sites within polymer monoliths in capillary columns using contactless conductivity detection

Connolly

O'Shea

Clark

et al. 2007

J of Separation Science

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Original PaperEvaluation of photografted charged sites within polymer monoliths in capillary columns using contactless conductivity detection Capacitively coupled contactless conductivity detection (C 4 D) is presented as a novel and versatile means of visualising discrete zones of charged functional groups grafted onto polymer based monoliths. Monoliths were first formed within 100 lm UV-transparent fused silica capillaries. Photografting methods were subsequently used to graft a charged functional monomer, 2-acrylamido-2-methyl-1-propanesulfonic acid, onto discrete regions of the monolith using a photomask. Post-modification monolith evaluation involves scanning the C 4 D detector along the length of the monolith to obtain a profile of the exact spatial location of grafted charged functionalities with millimetre accuracy. The methodology was extended to the visualisation of several zones of immobilised protein (bovine serum albumin) using photografted azlactone groups to enable covalent attachment of the protein to the monolith at precise locations along its length. In addition, the extent of non-specific binding of protein to the ungrafted regions of the monolith due to hydrophobic interactions could be monitored as an increase in background conductivity of the stationary phase. Finally, the technique was cross-validated using digital photography in combination with a UV light source by immobilising green fluorescent protein in discrete zones and comparing the results obtained using both complementary techniques.

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“…It greatly improved baseline stability and detec-tion sensitivity. C 4 D as a third option for ECD was introduced in coupling with CE by Zemann [116] and da Silva [117] in 1998. Its main strengths are contactless operation, high sensitivity, ease of miniaturization and quasi-universal detection [118].…”

Section: Electrochemicalmentioning

confidence: 99%

Portable capillary-based (non-chip) capillary electrophoresis

Ryvolová

Preisler

Brabazon

et al. 2010

TrAC Trends in Analytical Chemistry

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Miniaturized, portable instrumentation has been gaining popularity in all areas of analytical chemistry. Capillary electrophoresis (CE), due to its main strengths of high separation efficiency, relatively short analysis time and low consumption of chemicals, is a particularly suitable technique for use in portable analytical instrumentation. In line with the general trend in miniaturization in chemistry utilizing microfluidic chips, the main thrust of portable CE (P-CE) systems development is towards chip-based miniaturized CE. Despite this, capillary-based (non-chip) P-CE systems have certain unmatched advantages, especially in the relative simplicity of the regular cylindrical geometry of the CE capillary, maximal volume-to-surface ratio, no need to design and to fabricate a chip, the low costs of capillary compared to chip, and better performance with some detection techniques. This review presents an overview of the state of the art of P-CE and literature relevant to future developments. We pay particular attention to the development and the potential of miniaturization of functional parts for P-CE. These include components related to sample introduction, separation and detection, which are the key elements in P-CE design. The future of P-CE may be in relatively simple, rugged designs (e.g., using a short piece of capillary fixed to a chip-sized platform on which injection and detection parts can be mounted). Electrochemical detection is well suited for miniaturization, so is probably the most suitable detection technique for P-CE, but optical detection is gaining interest, especially due to miniaturized light sources (e.g., light-emitting diodes).

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Contactless Conductivity Detection for Capillary Electrophoresis

Cited by 511 publications

References 34 publications

A chip-based capillary electrophoresis-contactless conductivity microsystem for fast measurements of low-explosive ionic components

A chip-based capillary electrophoresis-contactless conductivity microsystem for fast measurements of low-explosive ionic components

Evaluation of photografted charged sites within polymer monoliths in capillary columns using contactless conductivity detection

Portable capillary-based (non-chip) capillary electrophoresis

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