Electrochemical detectors gold electrodes

Electrochemical oxidation-reduction of eluting mixture components is the basis for amperometric electrochemical detectors. The three electrodes needed for the detection, the working (indicator) electrode, reference electrode, and auxiliary electrode, are either inserted into the flow stream or imbedded in the wall of the flow stream. See Figure 13.13. The indicator electrode is typically glassy carbon, platinum, or gold, the reference electrode a silver-silver chloride electrode, and the auxiliary a stainless steel electrode. Most often, the indicator electrode is polarized to cause oxidation of the mixture components... 

There are two main varieties of bulk conductivity detectors contact and contactless. In a contact conductivity detector, the electrodes contact the column effluent directly. The electrodes are usually made of stainless steel, platinum, or gold in order to minimize electrochemical reactions, but they are still subject to fouling over time. In the absence of electrochemical reactions, there is no charge transfer between the solution and the electrodes, so the conductivity measurement is made with an oscillating or alternating voltage. 

Several types of electrodes have been successfully used with electrochemical detectors including carbon-paste, glassy carbon, platinum, mercury, and gold. Most widely used is the carbon-paste electrode, which is inexpensive and has low residual current. All analytes drat oxidize or reduce at the selected electrode potential can be detected. However, tliis electrode must be frequently standardized to maintain precise calibration because of changes that occur in its surface (128). 

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... 

Iodide in urine [39] and catecholamines [40,41] are example of analytes recently detected electrochemically and studied under IPC conditions. Pulsed amperometric detection on a gold electrode was used to detect etimicin [42] and gentamicin [43] in commercial samples, thus avoiding tedious pre-column derivatization. Heterocyclic aromatic amines in soup cubes [44] were determined by a coulometric electrode array detector, and the coulometric detection of a quinone-bearing drug candidate [45] allowed the study of electrochemical properties. 

Detector E, Dionex pulsed electrochemical detector, integrated timperometry mode, 1.4 mm gold working electrode with 0.005 inch gasket, El -t0.07 V, tl 400 ms, E2 -1-0.70 V, t2 120 ms, E3 1.00 V, t3 300 ms, stainless steel counter electrode, Ag/AgCl reference... 

Fig. 6. Schematic set up of the SI-ASV flow system CS, carrier solution Rl, holding coil R2, reaction coil SV, selection valve R, reductant S, sample MC, mixer chamber D, detector W, waste. Components of the electrochemical cell a, reference electrode b, tubular gold electrode c, glassy carbon counter electrode d, connector, e, O-ring.

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