Electrode carbon working

Figure 3.6-1 The electrochemical window of 76-24 mol % [BMMIM][(CF3S02)2N]/Li [(Cp3S02)2N] binary melt at a) a platinum working electrode (solid line), and b) a glassy carbon working electrode (dashed line). Electrochemical window set at a threshold of 0.1 mA cm. The reference electrode was a silver wire immersed in 0.01 m AgBp4 in [EMIM][BF4] in a compartment separated by a Vicor frit, and the counter-electrode was a graphite rod.

J. Gun and O. Lev, Voltammetric studies of composite ceramic carbon working electrodes. Anal. Chim. Acta, 294, 261-270 (1994). 

Calcitriol drug substance may be analyzed polaro-graphically, using a glassy carbon working electrode. The limiting current of the observed oxidation wave (E =... 

Fig. 18b. 7. (a) Chronoamperogram showing the response due to a triple pulse 500-0-500 with a 3 mm diameter glassy carbon working electrode in 2.0 mM Potassium Ferricyanide in 0.1 M KC1. No current was recorded for the initial potential, 500 mV, where no faradaic reduction took place, (b) The same solution, except with a 10 pm diameter Pt working electrode. Current was recorded for the initial potential at 500 mV for 0-4000 ms where no faradaic reduction took place. Note the magnitude of current scale. 

Figure 22 Cyclic voltammograms recorded in aqueous solutions of Rieske fragments from (a) bci complex glassy carbon working electrode pH 7.2 (b) (recombinant) biphenyldioxygenase (basal) pyrolitic graphite working electrode (in the presence of the positively charged additive neomycin) pH 7.0. Scan rate 0.01 V s ...

Data from Ref. Ill except for 94, from Ref. 119 in water subtract 0.2 V to obtain the Ag/AgCl values. Data from Ref. 110, obtained using a glassy carbon working electrode at 1-3 mM sample and 35 mM Et4NC104 in dry CH3CN (<0.02% water) at a scan speed of 100 mV s ... 

Data from Ref. 139, measured at 2 mM in CH3CN with 100 mM NaC104, with a glassy carbon working electrode and a scan speed of 300 mV s ... 

Cyclic voltammetry experiments were controlled using a Powerlab 4/20 interface and PAR model 362 scanning potentiostat with EChem software (v 1.5.2, ADlnstruments) and were carried out using a 1 mm diameter vitreous carbon working electrode, platinum counter electrode, and 2 mm silver wire reference electrode. The potential of the reference electrode was determined using the ferrocenium/ ferrocene (Fc+/Fc) couple, and all potentials are quoted relative to the SCE reference electrode. Against this reference, the Fc /Fc couple occrus at 0.38 V in acetonitrile and 0.53 V in THF [30, 31]. 

Palmore et al. first demonstrated the use of ABTS in a biofuel cell cathode, combining it with laccase from Pyricularia oryzae ABTS was dissolved at 2 mM in oxygen-saturated 0.2 M acetate buffer, pH 4, 25 °C. With a glassy carbon working electrode, an open-circuit potential of 0.53 V vs SCE was observed, reflecting the presence of HABTS in low-pH solution. Protonation of ABTS shifts the redox potential to 0.57 V vs SCE. With negligible stirring, current densities of 100 / A/cm were achieved at an electrode potential of 0.4 V vs SCE. 

Conditions 0.1 moldm NB114PF6 CH2CI2, Ag/AgN03 in MeCN as the reference electrode and glassy carbon working electrode scan rate = 100 mV s . Irreversible. 

Fig. 1 Cyclic voltammograms of Re02(bpy)(py)2 (solid line) and Re02(py)4+ (dashed line) at pH 2 on a glassy carbon working electrode (reprinted with permission from Ref 17, Copyright 1990 American Chemical Society).

Unless otherwise stated, most studies were performed by cyclic voltammetry with freshly polished glassy carbon working electrode (GC) and a saturated calomel reference electrode (SCE). 

A typical electrochemical reaction for an aromatic amine (benzidine) is shown in Figure 2. Most of the HPLC/EC work to date has been conducted using carbon working electrodes and thus the oxidative mode of the detector has been exploited (e.g. for benzidine) to the greatest extent. However, platinum and mercury have been used successfully for electroreducible species such as metal ions =/ and parathionC .). ... 

Ag/AgCl, equipped with a glassy carbon working electrode. 

TABLE 17.1 Electrochemical Properties of Cu(I) Mediators in ACN/LiC104 0.1 M, 100 mV/s Recorded Using a Glassy Carbon Working Electrode... 

Carbon working electrode 2 coated with mediator but no enzyme... 

AA and IAA simultaneously Yeast Metaphosphor ic acid/cold perchloric acid extraction Precolumn ODS-IO (40 X 2.6 mm Bio-Rad). Analytical Spherisorb ODS-2 (250 X 4.6 mm, 5 jum Rainin). 35°C. Isocratic 0.1 mM EDTA and 1.0 mM tetrabutyl-ammonium phosphate in 0.08 M acetate buffer, pH 4.2 + methanol (95 + 5, v/v). No flow rate reported. Electro- chemistry + 0.72 V vs. Ag/AgCl reference electrode, glassy carbon working electrode. External standardization. Linear range = 0-60 /ug/g yeast (dry weight). Reproducibility CV 2.3% for IAA, 1.2% for A A. Recoveries quantitative for both vitamers. 59... 

Broadly, the sensor contains, apart from the glassy-carbon working electrode, a reference electrode, a counter electrode, a temperature sensor and a pH glass electrode with associated reference electrode. As to the auxiliary sensor and electrodes, in the experiments on a laboratory scale, described in the previous chapters, types commonly used in research were employed. Here these need to be replaced by types which satisfy the above-mentioned requirements, which are discussed in the next section. 

Fig. 24.3. Cyclic voltammogram of ferrocene carboxylic acid at a bare carbon electrode (—), a poly(o-phenylenediamine)-coated working electrode (...) and at sonicated poly(o-phenylenediamine)-coated carbon working electrode (---).

The electrochemical cells used are three electrode strips, based on a carbon working electrode, a carbon counter electrode and a silver pseudo-reference electrode [1],... 

Glassy carbon working electrodes were used in electrochemical detection of pentazocine while no response was measured in one study at an operating potential of 0.8 V (94). Table 12 summarizes the HPLC column and mobile phase conditions utilized in reported investigations. 

Voltammetry. The voltammetric techniques are based on the current-voltagetime relationship at microelectrodes. To perform voltammetry, the oil/antioxidant sample is dissolved in a solvent containing an electrolyte and a three-electrode system (glassy carbon working electrode, a platinum wire reference electrode, and platinum wire auxiliary electrode) is inserted into an oil/solvent solution. A fresh oil typical of the application (100% standard) and the solvent system (0 % standard) is used to calibrate the voltammetric instrument for % remaining antioxidant determination (Kauffman, 1989 and 1991). 

Figure 10.5 Cyclic voltammograms in MeCN for (a) 3 mM Fe"(OPPh3)4(C104)2 and (i>) 3 mM (Ph3PO)4+FeIUOOH. Scan rate 0.1 V s l glassy-carbon working electrode (area 0.11 cm2).

Figure 13.1 Cyclic voltammograms (a) 3 mM [Fe(MeCN)4](C104)2 (b) 3 mM FeCl3 (c) 3 mM Fe(acac)3 (d) 3 mM Fe(Cp)2 (e) 3 mM Fe(CO)5 in MeCN (0.1 M tetra-ethylammonium perchlorate). Conditions scan rate 0.1 V s ambient temperature glassy-carbon working electrode (0.09 cm2) saturated calomel electrode (SCE) versus NHE, +0.244 V.

First of all, it is important to pay attention to the fact that most of the available literature data describes the behavior of a carbon working electrode against a laboratory counter- electrode which is normally metallic lithium. This counter-electrode is normally oversized and acts therefore as a nearly infinite source (and sink) of lithium ions. If the coulombic efficiency during cycling of the carbon electrode is less than 100% (e.g., due to side reactions, trapping of lithium in the carbon,... 

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