Multi-electrode array detector

C.N. Svendsen, Multi-electrode array detectors in high-performance liquid chromatography A new dimension in electrochemical analysis. Analyst, 1993, 118, 123-129. 

An electrochemical flow detector, based on four working electrodes coated with different permselective film types, for use in flow-injection measurements of multiple nitroaromatic explosives was recently developed [18]. The resulting array response (Fig. 4) offers unique fingerprints of such explosive compounds. Electrochemical devices are extremely attractive for designing such e-nose-type multi-electrode arrays that combine several partially selective electrodes and lead to a distinct response pattern (signature) for mixtures of organic vapors without prior separation [2],... 

Electrochemical detection is very sensitive for the compounds that can be oxidized or reduced at low-voltage potentials. Therefore, it could also be applied in the HPLC analysis of phenolic acids that are present in natural samples at very low concentrations. With the recent advances in electrochemical detection, multi-electrode array detection is becoming a powerful tool for detecting phenolic acids and flavonoids in a wide range of samples. The multi-channel coulometric detection system may serve as a highly sensitive way for the overall characterization of antioxidants the coulometric efficiency of each element of the array allows a complete voltametiic resolution of analytes as a function of their reaction (redox) potential. Some peaks may be resolved by the detector, even if they are unresolved when they leave the HPLC column. ... 

I. N. Acworth and M. Bowers, An Introduction to HPLC-Based Electrochemical Detection From Single Electrode to Multi-Electrode Arrays, in Coulometric Electrode Array Detectors for HPLC. Progress in HPLC-HPCE. 6, ed. I. N. Acworth, M. Naoi, S. Parvez and H. Parvez, 1997, VSP Publications, The Netherlands, pp. 3-50. 

The detector disclosed in US-A-S006711 refers to an HgCdTe multi-element detector array formed on a sapphire substrate. The elements have individual electrodes and a common electrode. When the electrodes are formed by a lift-off process, the maximum thickness of the metal layer forming the electrodes is limited due to the operational characteristics of the lift-off process. This results in a non-negligible resistance of the common electrode, which gives the device a low sensitivity. To reduce the resistance of the common electrode, an auxiliaiy electrode is formed on an aperture plate such that when the aperture plate is assembled onto the detector, the auxiliary electrode is pressed onto the common electrode. 

In another configuration of instmmentation, irradiation of white light onto the electrode surface and detection of reflected light by the use of a multi-channel detector (such as CCD or photo-diode array) through a grating monochromator makes multi-channel measurement possible [21]. 

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