Electrochemical detector system schematic

Fig. 11.12. Schematic diagram of a column-switching HPLC system. V-l, V-2, and V-3 switching valves. The position of °—c means position 1, and ° ° is position 2. P-1 and P-2 pumping system at 0.2 mL min-1 flow rate. Detector electrochemical detector with diamond electrodes. Column-1 and Column-2 Inertsil ODS-3. Loop 500 pL. A Mobile phase of 60% methanol-water containing 0.5% phosphoric acid.

Figure 4-9 Schematic of LC-EC system, with electrochemical detector monitoring the elution of analytes from an HPLC column, by either their oxidation or reduction (shown here as example) at a suitable thin-layer working electrode.

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),... 

Figure 3.18 Schematic diagram of a chip-based CE system with an external electrochemical detector.

In summer 1992, the first commercial electrochemical suppressor system was introduced the self-regenerating suppressor (SRS) [83, 84]. Its schematic differs from a micromembrane suppressor (see Fig. 3-72) only in the two platinum electrodes for the electrolysis of water, which are placed at the top and at the bottom between the regenerant chamber and the enclosure. The SRS comes complete with a power supply for applying an electric field for the electrolytic reactions. One advantage of this suppressor is that the water required for electrolysis can be delivered through the regenerant chaimels at a relatively low flow rate. Moreover, the de-ionized effluent of the detector cell after suppression can be used as a water source, so that an external water supply is no longer necessary. 

Figure 5.1 Schematic of capillary electrophoresis with electrochemical detection system, (a) High voltage supply (b) grounded platinum electrode (c) reference electrode (d) auxiliary platinum electrode (e) detection electrode (f) BCE (g) electrochemical detection reservoir (h) amperometric detector (I) recorder (j) anode reservoir (k) sample solution or BCE ( ) the inlet of capillary (m) platinum electrode for the high voltage and (n) fused silica capillary. Reprinted from Ref [5] with permission...

FIGURE 2.10 Schematic diagram of the SIA system for the evaluation of total antioxidant capacity with an in-house flow-through electrochemical detector (ECD) (1.9 cm width X 5.1 cm length x 2.3 cm height). CE, counter electrode WE, working electrode RE, reference electrode. (Reprinted with permission from Chan-Eam, S. et al. 2011. Talanta 84 1350-1354.)... 

FIGURE 31,14 (a) Schematic diagram of an FI system with the electrochemical detection of online generation of ABTS +. (b) Construction of a flow-through electrochemical detector, (c) FI signals obtained for water-soluble AOXs. The concentration of injected antioxidant solutions 250 pM for Tr, Asc, and uric acid 220 pM for reduced glutathione. (Modified from Milardovic, S., I. Kerekovic, and V. Rumenjak. 2007. Food Chem. 105 1688-1694.)... 

Schematic representation of the experimental setup is shown in Fig 1.1. The electrochemical system is coupled on-line to a Quadrupole Mass Spectrometer (Balzers QMS 311 or QMG 112). Volatile substances diffusing through the PTFE membrane enter into a first chamber where a pressure between 10 1 and 10 2 mbar is maintained by means of a turbomolecular pump. In this chamber most of the gases entering in the MS (mainly solvent molecules) are eliminated, a minor part enters in a second chamber where the analyzer is placed. A second turbo molecular pump evacuates this chamber promptly and the pressure can be controlled by changing the aperture between both chambers. Depending on the type of detector used (see below) pressures in the range 10 4-10 5 mbar, (for Faraday Collector, FC), or 10 7-10 9 mbar (for Secondary Electrton Multiplier, SEM) may be established.

Fig. 18b.1. Electrochemical cells and representative cell configurations, (a) Schematic diagram of a cell-potentiostat system, (b) Typical laboratory cell with Hg-drop electrode and drop knocker, (c) Voltammetric cell as detector at the end of a high-performance liquid chromatographic column, (d) A two-electrode (graphite) chip cell for biosensor development, (e) Three-electrode chip cells on a ceramic substrate for bioanalytical work.

The LD-17 is an electrochemical voltametric detector operating under diffusion-controlled conditions.) The effluent H2S concentration never exceeded 250 ppm and was usually less than 50 ppm. Evolution profiles were recorded by a strip-chart recorder. Figure 1 shows the schematic diagram of the H2S evolution system. 

A schematic diagram of a working FIA system is shown in Fignre 9.9. FIA can be nsed with many types of detector incinding electrochemical, e.g. pH probes, ISEs and condnc-tivity, and spectroscopic, e.g. UV-Vis, infrared and flnorescence. Diode array detectors allow the monitoring of many components simnltaneonsly, and conpled with chemometrics can be a very fast and information-rich technique. The detector itself should have a small cell volume to avoid undue dispersion. 

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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