Chloride ISE

The chloride concentration thus corresponds to the sulphite concentration in the test solution. The chloride ISE can be used for various thermodynamic measurements, such as determination of the activity of NaCl [361], also in the pressure range 0.1-60MPa and temperature of 0-25 [217]. This ISE is also... 

The sample is titrated with standardized silver nitrate (0.0141 M) in a continuously mixed beaker with an Ag electrode, an Ag/ AgCl electrode, or a chloride—ISE. The reference can be a glass mercuric sulfate, calomel, or Ag/ AgCl electrode. 

Table 3.18 Some characteristics of PVC nitrate and chloride ISEs (66-68)...

Ion Selective Electrodes Technique. Ion selective (ISE) methods, based on a direct potentiometric technique (7) (see Electroanalytical techniques), are routinely used in clinical chemistry to measure pH, sodium, potassium, carbon dioxide, calcium, lithium, and chloride levels in biological fluids. 

Fig. 10. Response of an ammonium ion-selective electrode which was made from nonactin dissolved in a PVC membrane mounted in a Phillips electrode body (ISE-561, Glasblaserie Mitller, Zurich) referenced against an SCE to a spHt-stream EIA system, (a) EIA response to injected standards containing both glutamine and ammonium chloride lines A—E contain both glutamine and ammonium chloride E—G contain only glutamine, (b) Strip-chart...

The selectivity coefficients () of ISEs with polyfvinyl chloride)... 

Only recently, we have shown experimentally for a selection of neutral ionophores and carefully purified, typical PVC plasticizers that in absence of ionic sites Nernstian EMF responses could not be obtained [55]. For plasticizers of low polarity no EMF responses were observed at all. Transient responses due to salt extraction even with the highly hydrophilic counterion chloride were observed in the case of the more polar nitrobenzene. Lasting primary ion-dependent charge separation at the liquid liquid interfaces of ISEs, resulting in a stable EMF response, seemed therefore only possible in the presence of ionic sites confined to the membrane phase. Because membranes free of impurity sites... 

For the halide ISEs on the basis of silver sulphide we may assume, e.g., in the case of chloride, the following exchange reaction ... 

Clinical chemistry, particularly the determination of the biologically relevant electrolytes in physiological fluids, remains the key area of ISEs application [15], as billions of routine measurements with ISEs are performed each year all over the world [16], The concentration ranges for the most important physiological ions detectable in blood fluids with polymeric ISEs are shown in Table 4.1. Sensors for pH and for ionized calcium, potassium and sodium are approved by the International Federation of Clinical Chemistry (IFCC) and implemented into commercially available clinical analyzers [17], Moreover, magnesium, lithium, and chloride ions are also widely detected by corresponding ISEs in blood liquids, urine, hemodialysis solutions, and elsewhere. Sensors for the determination of physiologically relevant polyions (heparin and protamine), dissolved carbon dioxide, phosphates, and other blood analytes, intensively studied over the years, are on their way to replace less reliable and/or awkward analytical procedures for blood analysis (see below). 

Consider the case in which the solubility of silver chloride is being measured by using a silver ion-selective electrode (ISE). The ISE is immersed in a solution... 

The individual activity coefficients calculated from (4.12), suitable for calibration of ISEs for chloride ions, the alkali metal and alkaline earth ions, are given in tables 4.1 and 4.2. Ion activity scales have also been proposed for KF [141], choline chloride [98], for mixtures of electrolytes simulating the composition of the serum and other biological fluids (at 37 °C) [106,107], for alkali metal chlorides in solutions of bovine serum albumine [132] and for mixtures of electrolytes analogous to seawater [140]. 

Other types of ISE with silver halides are based on homogeneous membranes [6, 383]. With silver chloride or bromide, a single crystal or membrane from a salt melt can be prepared, while silver iodide membranes are prepared from... 

These types of electrodes for chloride and bromide ions have resistances of less than 30Mf2, while that of the iodide ISE lies between 1 and 5 [263]. 

A good deal of attention has been devoted to the effect of chlorides on the behaviour of Cu ISEs [221, 325,441] (for a review see [129]). While in the absence of chloride the ISE potential depends linearly on the logarithm of the Cu activity, with Nernstian slope of 0.0296 V (25 °C), at chloride concentrations greater than the Cu concentration the slope changes to 0.0591 V and a marked response to the chloride ion activity appears. Westall et al. [441] state that contact of Cu with the membrane leads to electrode oxidation,... 

In the presence of chloride the CUCI2 complex is formed, shifting the equilibrium at the electrode surface to the right. At a sufficiently large Cl" concentration, the ISE potential obeys the relationship... 

The solid-membrane ISE has certain disadvantages for the determination of chloride inside cells and thus ion-selective microelectrodes containing ion-exchanger Corning No. 477315 (based on a nitroxylene mixture) are used [223]. Reviews of intracellular applications of this electrode can be found in [23, 78, 86, 211,217]. 

An important advance in ion-selective electrodes (ISEs) and related systems was based on the concept of polymeric liquid membranes developed by Eisenman [122]. The principle of this approach was to incorporate an organic compound as the ionophore into a polyvinyl chloride membrane... 

Figure 4.13 — (A) Serially arranged ISEs for the simultaneous determination of sodium, potassium, calcium and chloride ions. (B) Serially and parallelly arranged ISEs for the simultaneous determination of T, Br", Cl and F . WE working electrode PC personal computer Ej-E r, Cr, Br" and F ISEs, respectively C C3 amalgamated-lead columns (1.5 and 2.5 cm long, respectively) AgCl column RE reference electrode PHM pH/mV-meter S sample injection CS carrier stream P pump R chart recorder W waste. (Reproduced from [126] and [127] with permission of Elsevier Science Publishers and Pergamon Press, respectively).

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