Detectors dual working electrod

Draw clearly schematic diagrams of a thin-layer flow detector utilizing (1) single working electrode, and (2) dual electrode. Explain how the latter improves the power and information content. 

The electronic tongue system based on flow injection analysis (FIA) with two amperometric detectors was set up. The FLA apparatus consisted of a Jasco (Tokyo, Japan) model 880 PU pump and two EG G Princeton Applied Research (Princeton, NJ, USA) Model 400 thin-layer electrochemical detector connected in series. Each detector was equipped with a working electrode (a dual glassy carbon electrode and a gold... 

Detector E, Bioanalytical systems Model LC-4B, dual glassy-carbon working electrode used in parallel mode, +0.65 V and +0.80 V (monitored), stainless steel auxiliary electrode, Ag/AgCl reference electrode following post-column reaction. The column effluent flowed at 0-5° through a 2 mL knitted coil of 0.5 mm i.d. PTFE tubing irradiated with a low pressure mercury lamp (Photronix Model 816) to the detector. 

Fig. 20. (A) Thin-layer dectrochemical detector with external rererenceoompattment. (B) Condensed detector cell with internal reference electrode and negligible uncompensated resistance. In both schemes, the working electrode block is interchangeable to provide various dual-and single-electrode configurations. The condensed cell is directly suital Ibr mkrobore LC. Reproduced with permission from Bioanalytkal Systems Inc.. West Lafayette, Indiana.

Electrochemical detector an instrument with dual glassy carbon working electrodes (W1 and W2), positioned in parallel (Bioanalytical Systems). Set the operating potential ofWl at 600 mV (the maximal oxidation potential of 5HT) and of... 

FIGURE 8 Electrochemical detector cell (Bioanalytical Systems, Inc.), (a) Diagram of the flow cell. A = auxiliary electrode, W = working electrode. R = reference electrode, (b) Dual thin-layer working electrodes in parallel (1) and series (2) configurations. [From Bratin K., and Kissinger, P. T. (1981). J. Liq. Chromator. 4, 321-57. Reprinted with permission from Marcel Dekker, Inc.]... 

Phenol and the three dihydroxybenzenes (20, 42, 66) in water were determined by LLE with a hydrophilic solvent followed by amperometric titration. LOD was in the ppm range . A dual electrode in a FIA system has been used as detector for total phenols in wastewater. The upstream coulometric electrode has a large surface area and is used to eliminate compounds that cause interference and the second one is an amperometric electrode for oxidative detection of all phenols. Optimal results were found working with a phosphate buffer at pH 6.8, at potentials of +0.35 V and +0.78 V for the coulometric and amperometric electrodes, respectively. A high sample throughput of 60 per hour can be attained with RSD of 0.1-4%. This method is more reliable than the colorimetric method . The concentration of fenobucarb (142) in drinking water was determined after a short alkaline hydrolysis, and oxidation of the resulting 2-s-butylphenol with a GCE at 750 mV, pH 3.5 LOD was 3.6 x 1Q- M, RSD 3.74% for 1 x IQ- M (n = 11, p = 0.05)37 . 

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