Electrodes specificity

Specific breakage rate Specific conductivity Specific ion electrode Specific properties... 

Specific-Ion Electrodes In addition to the pH glass electrode specific for hydrogen ions, a number of electrodes that are selective for the measurement of other ions have been developed. This selectivity is obtained through the composition of the electrode membrane (glass, polymer, or liquid-liquid) and the composition of the elec trode. Tbese electrodes are subject to interference from other ions, and the response is a function of the total ionic strength of the solution. However, electrodes have been designed to be highly selective for specific ions, and when properly used, these provide valuable process measurements. 

Equation (2.33) now defines the double layer in the final model of the structure of the electrolyte near the electrode specifically adsorbed ions and solvent in the IHP, solvated ions forming a plane parallel to the electrode in the OHP and a dilfuse layer of ions having an excess of ions charged opposite to that on the electrode. The excess charge density in the latter region decays exponentially with distance away from the OHP. In addition, the Stern model allows some prediction of the relative importance of the diffuse vs. Helmholtz layers as a function of concentration. Table 2.1 shows... 

Side length of a square electrode Specific resistivity of the electrolyte... 

Fig. 14.14 Structural composition of a PEMFC electrode, specifically of a cathode.

It must be noted here that the observation made by Zhang et al. about the dominating magnitude of Ret could be electrode-specific because Ra is not always higher than Rsei in all systems and at all temperatures. At least in the works by Smart et al 461,462 and Wang et al., " R in magnitude is comparable with or even smaller than 7 sei- Certainly,... 

Tissue electrodes [2, 3, 4, 5, 45,57], In these biosensors, a thin layer of tissue is attached to the internal sensor. The enzymic reactions taking place in the tissue liberate products sensed by the internal sensor. In the glutamine electrode [5, 45], a thick layer (about 0.05 mm) of porcine liver is used and in the adenosine-5 -monophosphate electrode [4], a layer of rabbit muscle tissue. In both cases, the ammonia gas probe is the indicator electrode. Various types of enzyme, bacterial and tissue electrodes were compared [2]. In an adenosine electrode a mixture of cells obtained from the outer (mucosal) side of a mouse small intestine was used [3j. The stability of all these electrodes increases in the presence of sodium azide in the solution that prevents bacterial decomposition of the tissue. In an electrode specific for the antidiuretic hormone [57], toad bladder is placed over the membrane of a sodium-sensitive glass electrode. In the presence of the antidiuretic hormone, sodium ions are transported through the bladder and the sodium electrode response depends on the hormone concentration. 

O2 evolution was measured with a Clark-type electrode. Specific activity of the untreated controls averaged 40 9 ymoles 0 evolved/mg Chi h. Data shown are arithmetic averages SD of determinations made with a minimum of three different isolations of chloroplasts. 

Elemental composition Na 46.92%, C 24.50%, N 28.58%. An aqueous solution is analyzed for sodium. Cyanide is measured by an electrode specific to cyanide ion. Alternatively, cyanide may be measured by pyridine-barbituric acid colorimetric test (See Hydrogen Cyanide). 

What makes a liquid-based ion-selective electrode specific for one analyte ... 

The synthesis of nanostructured carbon using aliphatic alcohols as selfassembling molecules has demonstrated that this strategy can be extended beyond metal oxide-based materials [38]. Recently, we have reported the synthesis of a novel carbon material with tunable porosity by using a liquid-crystalline precursor containing a surfactant and a carbon-yielding chemical, furfuryl alcohol. The carbonization of the cured self-assembled carbon precursor produces a new carbon material with both controlled porosity and electrical conductivity. The unique combination of both features is advantageous for many relevant applications. For example, when tested as a supercapacitor electrode, specific capacitances over 120 F/g were obtained without the need to use binders, additives, or activation to increase surface area [38]. The proposed synthesis method is versatile and economically attractive, and allows for the precise control of the structure. 

Snook GA, Peng C, Chen GZ, Fray DJ. Achieving high electrode specific capacitance with materials of low mass specific capacitance Potentiostatically grown thick micro-nanoporous PEDOT film. Electrochemistry Communications 2007 9 83-88. 

The No. 4 sample was doped into the conventional micron -Ni(OH)2 at ratios of 5%, 8% and 12%, respectively. The results of charging and discharging experiments are shown in Figure 3. The nano jff-Ni(OH)2 doping increases the electrode specific capacity, in which the 8% nano 5-Ni(OH)2 doping increased the 11% electrode specific capacity. 

The lipophilic phosphonium cations, TPP (tetraphenyl phosphonium) and TPMP" (triphenylmethyl phosphonium) can cross bilayer membranes as charged species and distribute according to the membrane potential [26]. Since they can be used at very low concentration they tend to disturb the potential less than the use of valinomycin. The gradients established can be estimated either iso topically, or by the use of an electrode specific to the cation [27]. The latter allows the membrane potential in mitochondrial incubations to be monitored continuously. However, a disadvantage of these cations, particularly in the case of TPP, is that they do not behave ideally but bind to components in the matrix. A number of techniques have been described for correcting the accumulation ratios of the cations [28,29]. 

Methods that involve the introduction of electrodes into natural media without contamination are most appealing. The glass electrode has proved to be sufficiently specific and sensitive. Other electrodes specific for more than a dozen ions have joined the pH-type glass electrode in commercial production. Many of these electrodes are sufficiently specific and sensitive to permit measurement or monitoring of individual solution components. 

Turbidity All On-site, on-line, in-situ No Nephelometry, photometry (UV, IR, multi-wavelength) Electrodes (specific, glass, polymer, LIS and reference) Few seconds 1-10% 0-4000 NTU ISO 7027 DIN 38404 USEPA 180.1 ABB Instrumentation, Anael, Aquacontrol, Aqualyse, Aquams, AWA Instruments, Bamo mesures, Datalink, EFS Lac Instruments et systemes, Endress Hauser, Equipements scientifiques SA, Hydrolab, Martec, Mettler Toledo, OTT, Hach, Seres, Cole Parmer, WTW, YSI Hydrodata... 

Ion selective electrodes provide a simple and accurate method for the determination of many ions in solution. These have been developed using the same electrochemical principles as the pH electrode, which is basically an ion selective electrode specific for hydrogen ion. Thus, concentrations of Na+, K+, Ca +, and Pb + as examples of cations, and F , Cl , Br , I", and CN as anions may all be measured using this method. With the appropriate measuring precautions and attention to possible interferences, most cations can be determined at concentrations as low as 10 to 10" M, and lead for example down to 10 M. 

Many factors affect the storage, operating life, and performance characteristics of Li batteries. Among them, the presence of a passive layer formed upon exposure of metallic Li electrodes to various non-aqueous solvents is essential to the operation of the Li electrodes Specifically,... 

In the next theory, two layers were defined on the solution side—inner and outer Helmholtz planes 9,10). The inner Helmholtz plane is the locus of centers of unhydrated ions adsorbed on the electrode (specifically adsorbed ions) and the outer Helmholtz plane is the locus of centers of hydrated ions adjacent to the electrode. Three regions are to be considered— the regions between (i) the metal and the inner Helmholtz plane, ii) the inner and the outer Helmholtz planes, and (Hi) the outer Helmholtz plane and the bulk of the solution (Fig. 1). 

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