Electrochemical detectors, for liquid

A. Yildiz, P. T. Kissinger, and C. N. Reilley, Anal. Chem. 40 1018 (1968). (A host of intriguing thin-layer cell applications are suggested, including the possibility of thin-layer electrochemical detectors for liquid chromatography, realized several years later by Kissinger and Adams.)... 

The modern interest in electrochemical detectors for liquid chromatography was stimulated by the recognition that this technique was ideal for the study of aromatic metabolism in the mammalian central nervous system. Most of the papers published during the past 20 years have focused on applications of the LCEC technique to neurochemical problems. Since the First commercial detectors became available in 1974, a number of other areas of application have been explored as well. The trade publication Current Separations provides a useful... 

Another recent development is the advent of pulse amperometry in which the potential is repeatedly pulsed between two (or more) values. The current at each potential or the difference between these two currents ( differential pulse amperometry ) can be used to advantage for a number of applications. Similar advantages can result from the simultaneous monitoring of two (or more) electrodes poised at different potentials. In the remainder of this chapter it will be shown how the basic concepts of amperometry can be applied to various liquid chromatography detectors. There is not one universal electrochemical detector for liquid chromatography, but, rather, a family of different devices that have advantages for particular applications. Electrochemical detection has also been employed with flow injection analysis (where there is no chromatographic separation), in capillary electrophoresis, and in continuous-flow sensors. 

Electrochemical detectors for liquid chromatography have reached a level of maturity in that thousands of these devices are used routinely for a variety of mundane purposes. Nevertheless, the technology is advancing rapidly in several respects. Multiple electrode and voltammetric detectors have been developed for more specialized applications. Small-volume transducers based on carbon fiber electrodes are being explored for capillary and micropacked columns. Recently, electrochemical detection has also been coupled to capillary electrophoresis [47]. Finally, new electrode materials with unique properties are likely to afford improved sensitivity and selectivity for important applications. 

Kissinger, P.T. Refshauge, C. Dreiling, R. Adams, R.N. Electrochemical detector for liquid chromatography with picogram sensitivity. Anal. Lett. 1973, 6, 465 77. 

For a recent description of coinmercialJy available electrochemical detectors for liquid chromatography, see B. E. Erick.son. Af a/. Chew.. 2000, 72. 353A. 

Z. Niegreisz, L. Szucs, J. Fekete, G. Horvai, K. Toth, and E. Pungor, Modifications of the Wall-Jet Electrochemical Detector for Liquid Chromatography and Flow Analysis. J. Chromatogr., 316 (1984) 451. 

As in the previous work, the flow injection system consisted of a Cole Parmer Mas-terflex peristaltic pump, Rheodyne 7125 injector, Bioanalytical System (BAS) TL-5A flow through electrochemical cell and either an IBM EC/230 or a BAS CV 37 potentiostat. These instruments respectively are designed for use with an electrochemical detector for liquid chromatography and for low current measurements such as with ultramicroelectrodes. A pulse dampener was also included in the flow system. 

WiGHTMAN, R. M., Pair, E. C., Borman, S., and Dayton, M. A., 19786, Evaluation of the basal plane of pyrolytic graphite as an electrochemical detector for liquid chromatography, Anal. Chem. 50 1410-1414. 

J.N. Barisci and G.G. Wallace, Electrochemical detectors for liquid chromatography, Chim. Oggi., 1990, 9-13. 

D.L. Rabenstein and R. Saetre, Mercury-based electrochemical detector for liquid chromatography for the detection of glutathione and other sulfur-containing compounds. Anal Chem., 1977, 49, 1036-1039. 

L.C. Blank, Dual electrochemical detector for liquid chromatography, J. Chromatogr., 1976, 117, 35 6. 

Brunt, K., Electrochemical detectors for high-performance liquid chromatography and flow analysis systems, Trace Analysis, Vol. 1, Lawrence, J. F., Ed., Academic Press, New York, 1981, 47-120. 

With the introduction of modern electronics, inexpensive computers, and new materials there is a resurgence of voltammetric techniques in various branches of science as evident in hundreds of new publications. Now, voltammetry can be performed with a nano-electrode for the detection of single molecular events [1], similar electrodes can be used to monitor the activity of neurotransmitter in a single living cell in subnanoliter volume electrochemical cell [2], measurement of fast electron transfer kinetics, trace metal analysis, etc. Voltammetric sensors are now commonplace in gas sensors (home CO sensor), biomedical sensors (blood glucose meter), and detectors for liquid chromatography. Voltammetric sensors appear to be an ideal candidate for miniaturization and mass production. This is evident in the development of lab-on-chip... 

H. R. Dales, An Assessment of the Use of High Performance Liquid Chromatography with an Electrochemical Detector for the Analysis of Explosive Residues (M.Sc. thesis, University of Strathclyde, August 1989). 

To many analysts the major limitation of electrochemical detection for liquid chromatography (LCEC) is its limited applicability to gradient elution techniques. Amperometric electrochemical detectors exhibit both the best and the worst characteristics of solute property and bulk property detectors. While the Faradaic current arises only from the solute, the non-Faradaic current arises from... 

Fleet, B. Little, C.J. Design and evaluation of electrochemical detectors for HPLC [high-pressure liquid chromatography]. J. Chromatogr. Sci. 1974,12, 747-752. 

M. Goto, N. Nakamura and D. Ishii, Micro high-performance liquid chromatographic system with micro precolumn and dual electrochemical detector for direct injection analysis of catecholamines in body fluids, J. Chromatogr, 226, 33 42 (1981). 

R. J. Rucki, Electrochemical detectors for flowing liquid systems, Talanta, 27,147,1980. 

H. W. van Rooijen and H. Poppe, An Electrochemical Reactivation Method for Solid Electrodes Used in Electrochemical Detectors for High-Performance Liquid Chromatography and Flow Injection Analysis. Anal. Chim. Acta, 130 (1981) 9. 

D. E. Weisshaar, Application of Kelgraph to Electrochemical Detectors for Flow Injection Analysis and High Performance Liquid Chromatography. Gov. Rep. Announce. Index (U.S.), 83(20) (1983) 4961. 

T. P. Tougas, An Electrochemical Detector for High Performance Liquid Chromatography and Flow Injection Analysis Based on a Reticulated Vitreous Carbon Working Electrode. Diss. Abstr. Int. B, 43 (1983) 3971. 

Electrochemical detectors for the determination of trace amounts of ionic and molecular components in liquid chromatographic effluents are sensitive, selective, and inexpensive. Figure 15.37 shows a schematic of an EC system with electrochemical detection. For many separations, they provide the best means of detection, outperforming, for example, ultraviolet (UV)/visible (VIS),... 

Hirata, Y., Lin, P. T., Novotny, M., and Wightman, R. M., 1980, Small-volume electrochemical detector for microcolumn liquid chromatography,y. Chromatogr. 181 287-294. 

G. Weber, Detection based on electrical and electrochemical measurements in Detectors for Liquid Chromatography, E.S. Yeung (ed.), Wiley, New York, Chapter 7, 1986. 

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