Detector for capillary electrophoresis

FIGURE 3-23 Schematic of a carbon-fiber amperometric detector for capillary electrophoresis A, fused silica capillary B, eluent drop C, stainless steel plate RE, reference electrode WE, working electrode, AE, auxiliary electrode. (Reproduced with permission from reference 58.)... 

For many applications, diode array detection has become routine. A photodiode array was used for simultaneous detection of 100 capillaries in zone electrophoresis and micellar electrokinetic chromatography (MEKC).1516 Deflection of a laser beam by acoustic waves was reported as a means to scan six capillary channels on a microchip.17 The design of a low-noise amperometric detector for capillary electrophoresis has been reported.18... 

Krattiger B, Bruin GJM, Bruno AE. Hologram-based refractive-index detector for capillary electrophoresis—Separation of metal-ions. Analytical Chemistry 66, 1-8, 1994. 

Early in the development of capillary electrophoresis, it was noted that the successful detection of separated sample components present within the narrow confines of these capillary tubes posed a major challenge (2)- In response to this challenge, much research has been directed toward the development of sensitive and selective detectors for capillary electrophoresis. CE detector technology has been largely borrowed from the field of high-performance liquid chromatography (HPLC), especially from micro-column HPLC. 

We report here the design and characterization of three simple, on-line radioisotope detectors for capillary electrophoresis. The first detector utilizes a commercially available semiconductor device responding directly to 7 rays or particles that pass through the walls of the fused silica separation channel. A similar semiconductor detector for 7-emitting radiopharmaceuticals separated by HPLC was reported by Needham and Delaney (XI). The second detector utilizes a commercially available plastic scintillator material that completely surrounds (360 ) the detection region of the separation channel. Light emitted by the plastic scintillator is collected and focused onto the photocathode of a cooled photomultiplier tube. Alternatively, a third detection scheme utilizes a disk fashioned from commercially available plastic scintillator material positioned between two-room temperature photomultiplier tubes operated in the coincidence counting mode. 

Three simple, on-line radioisotope detectors for capillary electrophoresis were described and characterized for the analysis of 43P-labeled analytes. The minimum limit of detection for these systems was shown to be strongly dependent upon the conditions under which the analysis is performed. For standard CE separations performed at a relatively high (constant) voltage, the minimum limit of detection was found to be in the low nanocurie (injected sample... 

Toulas, C., and Hernandez, L. (1992). Applications of a laser-induced fluorescence detector for capillary electrophoresis to measure attomolar and zeptomolar amounts of compounds. LC-GC 10(6), 471-476. 

Wang and eoworkers [66] reported on the use of CNTPE containing Cu as a detector for Capillary Electrophoresis for the determination of carbohydrates compoimds. The electrode was prepared by hand mixing mineral oil, MWCNT and copper powder in a weight ratio 1 1 2 (carbon/oil/Cu). 

The use of MWCNT eomposite electrodes containing Cu as a detector for capillary electrophoresis determination of carbohydrates eompounds was also reported [66]. The oxidation of suerose, galactose and fruetose at Cu-CNTPE started at potentials around 0.2 V lower than at Cu electrodes allowing in this way... 

In the outside-out model, the pipette is attached to the entire cell as in the whole cell model, followed by a sharp pull that causes the cell membrane to break and reseal with the pipette tip (Fig. 3b). With the extracellular region exposed, channel activity as a response to different external stimuli can be probed. This configuration is less common than the inside-out method. Using an outside-out method, single-channel opening activity has been recorded while various neurotransmitters were released. For example, this patch clamp method was used as a detector for capillary electrophoresis separations of GABA, glutamate, and NMDA (7). 

Mass spectrometric detectors for capillary electrophoresis are necessarily post-column detectors and must be interfaced to the cathodic end of the capillary. These detectors consist of four main components the interface, that joins the capillary to the ion source, the ion source, that generates ionic fragments from neutral analyte species, the mass analyzer, that distinguishes ions by their mass/charge (m/z) values, and the ion detector, that measures and amplifies the signal. The principles and instrumentation of bioanalytical MS are explained in Chapter 15. 

Zhu H, White IM, Suter JD et al (2007) Integrated refractive index optical ring resonator detector for capillary electrophoresis. Anal Chem 79 930-937... 

Ding, S. N., Xu, J. J., and Chen, H. Y, Tris(2,2 -bipyridyl)mthenium(II)-zirconia-Nafion composite films applied as solid-state electrochemiluminescence detector for capillary electrophoresis. Electrophoresis, 26,1737, 2005. 

E., Zapardiel, A., Rubianes, M.D., and Rivas, GA. (2005) Carbon nanotubes paste electrodes as new detectors for capillary electrophoresis. Anal. Chim. Acta, 543 (1-2), 84-91. 

PI A.). Zemann, K. Mayrhofer, E. Schnell. and G. K. Bonn. Contactless conductivity detector for capillary electrophoresis. Book of Abstracts. 216 ACS National Meeting, Boston. August 23-27, ANYLO-75,1998. 

Fracassi da SUva, J.A. and Lago, C.L., An oscUlometric detector for capillary electrophoresis. Anal. Chem., 70,4339,1998. 

Zhong, M. Lunte, S.M. Integrated On-Capillary Electrochemical Detector for Capillary Electrophoresis. Anal. Chem. 1996 69, 2488—2493. 

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