Ag-AgCl reference electrodes

Figure 7.8 Schematic representation of a typical wall-jet electrode used for electroanalytical measurements (a) contact to Pt disc electrode (the shaded portion at the centre of the figure) (b) contact to ring electrode (c) AgCl Ag reference electrode (d) Pt tube counter electrode (e) cell inlet (f) cell body (made of an insulator such as Teflon), (b) A typical pattern of solution flow over the face of a wall-jet electrode, showing why splash back does not occur. Part (a) reproduced from Brett, C. M. A. and Brett, A. M. O., Electroanalysis, 1998, 1998, by permission of Oxford University Press.

Ag AgCl, KC1 salt bridge sample membrane internal solution, AgCl Ag Reference electrode Ion-selective electrode... 

Fig. 83. A schematic picture of a glass electrode a) A thin bulb of special glass (b) A holder of regular, thick glass (c) The level of the HCl solution (d) The AgCl/Ag reference electrode.

We have briefly encountered the solid-state fluoride electrode, which has a fully nemstian response down to c. 10 mol dm . The fluoride electrode is iiiunersed in a test solution of fluoride ion (usually aqueous), and the emf is then determined. At its heart is a single crystal of lanthanum fluoride doped with erbium fluoride, (see Figure 3.10). Like the pH electrode, a full fluoride electrode also contains a small reference electrode, meaning that a fluoride electrode is in reality a cell. The fluoride electrode does not suffer from interference from CP, so an AgCl Ag reference is the normal choice owing to its convenience and compact size. 

Figure 4.17 — (A) Exploded view of a tubular flow-cell integrated microconduit system. I Ag/AgCl inner reference electrode M sensitive membrane S internal reference solution. (B) Detail of the integrated microconduit shown within the dotted lines in C. (C) Integrated-microconduit FI manifold for potentiometric measurements C carrier stream R reference electrode solution P pump V injection valve I indicator electrode R reference electrode I pulse inhibitor G ground W waste. (Reproduced from [140] with permission of Pergamon Press).

Hamada et al. used a poly (vinyl chloride) matrix membrane ion-selective electrode for the analysis of procaine [76]. Procaine flavianate (10 mg, prepared by precipitation from an equimolar mixture of procaine hydrochloride and flavianic acid), was mixed with PVC powder (150 mg), dioctyl phthalate (370 mg), and tetrahydrofuran (4 mL). This mixture was used to produce membranes (3 cm diameter), from which discs were cut to prepare ion-selective electrodes. The electrodes were used in conjunction with a double-junction Ag-AgCl (KNO3) reference electrode for the potentiometric determination of procaine hydrochloride at 25°C. 

For the measurement of the open circuit potential of the catalyst during the oxidation reaction a Pt rod measuring electrode and a Ag/AgCl/KCljat reference electrode were applied (13,14). 

All aqueous potential values are referenced to the standard hydrogen electrode. Nonaqueous potential values are referenced to ferrocene (Fc) if possible. Other references are indicated in parentheses where SCE represents the standard calomel electrode, A1 represents the Ag/Ag+ reference electrode ([Ag+] = 0.01 M unless otherwise indicated) and A2 represents the Ag/AgCl reference electrode. In acetonitrile, potential values referenced to SCE may be corrected to the ferrocene reference standard by subtracting 0.380 V, depending upon the anion present (a) Ref 11, (b) Ref 10c. c [Ag+] = 0.1 M. 

The coulometric method was also applied to the determination of the number of electrons involved in the two-step polarographic reduction of chlor-diazepoxide [18]. The reduction of a 2.5 x 10 5 M solution of the compound in 0.1 N H2S04 yielded n values of 1.97 and 4.06, respectively, at a mercury pool cathode employing working electrode potentials of -0.45 V and -0.90 V vs. Ag/AgCl wire reference electrode. 

The three electrodes GECE as working electrode, the Ag/AgCl as reference electrode and the platinum as auxiliary electrode, are immersed in a 25 ml electrochemical cell containing 0.1 M acetate buffer (pH 4.5) and 400 pg/1 of bismuth. During the stripping step, the current is recorded in quiescent solution. 

In the meantime, set the chronoamperometric unit with the Ag/ AgCl as reference electrode, the platinum as auxiliary electrode and the modified GEC electrode as working electrode. Set the potential fixed at — 0.100 V. 

Probe immobilisation The sequence (probe) was diluted in 2 x SSC at the final concentration of 40 gg/ml, and immobilised onto the working electrode surface applying +0.5V (vs. Ag/AgCl pseudo-reference electrode) for 5 min in stirring condition. 

The guanine redox activity of the target DNA was used to detect the duplex formation by carrying out a square-wave voltammetric measurement (SQW). The results of the parameters optimisation for the probe concentration (40 pg/ml), immobilisation time (5 min by applying a positive potential of +0.5V vs. Ag/AgCl pseudo reference electrode) and hybridisation time (10 min without any potential) were very similar to those obtained in previous work [3]. 

Redox Pt electrode and Ag/AgCl, Cl, reference electrode, N2 flushing Anese and Nicoli446... 

Taking one sensor at a time, lower a screen-printed Ag/AgCl counter/reference electrode strip into the sensor well and connect this and the working electrode to the potentiostat. 

The enzyme-modified working electrode is covered with lOpL of buffer after 5 min, the solution is removed. Then, 200 pL of ATCh chloride (enzymatic substrate) solution (ImM) are casted onto the cell after 10 min, the potential was applied and the current response at 30s is evaluated. Chronoamperometric measurements are performed at the applied potential of +0.1 V vs. pseudo Ag/AgCl reference electrode (see Fig. 3). All potentials are referred to the screen-printed Ag/AgCl pseudo-reference electrode the experiments are carried out at room temperature (25°C). 

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