Ion-selective electrodes iodide

Iodide ion-selective electrode The iodide electrode has broad application both in the direct determination of iodide ions present in various media as well as for the determination of iodide in various compounds. It is, for example, important in the determination of iodide in milk [44,64,218, 382, 442], This electrode responds to Hg ions [150, 306, 439] and can be used for the indirect determination of oxidizing agents that react with iodide, such as 10 [305], lOi [158], Pd(II) [117, 347,405] and for the determination of the overall oxidant content, for example in the atmosphere [393], It can also be used to monitor the iodide concentration formed during the reactions of iodide with hydrogen peroxide or perborate, catalyzed by molybdenum, tungsten or vanadium ions, permitting determination of traces of these metals [12,192,193, 194, 195]. The permeability of bilayer lipid membranes for iodide can be measured using an I"... 

D. Dobcnik, J. Stergulec, and S. GomiScek, Preparation of an Iodide Ion-Selective Electrode by Chemical Treatment of a Silver Wire, Fresenius J. Anal. Chem. 1996, 354, 494. 

The selectivity coefficient of an iodide ion-selective electrode for bromide ion is to be determined using the equation derived in problem 14, above. An iodide ion-selective electrode and an appropriate reference dec-trode are equilibrated in 50.0 ml of 1.00 x 10" MKI at 25°C. The equilibrium potential is -130.2 mV. Then, 0.50-, 1.00-, 2.00-, and 2.00-ml aliquots of 1.00 M KBr are added sequentially. After each addition, the equilibrium potential is measured -131.5, -133.9, -137.5, and -140.8 mV, respectively. Determine the selectivity coefficient for bromide ion if the slope of the calibration curve for iodide is 59.2 mV/ decade. What assumptions have been made in this approach ... 

The same reaction has been studied in a flow system coupled with a sensor-reference pair of iodide ion-selective electrodes but with the more efficient peroxidase catalyst substituted for molybdenumfVl) [386]. Maltose and cello-biose interfere while samples containing the more serious ascorbic acid, tyrosine or uric acid interferents require pre-treatment [386]. 

Kolar, M. and D. Dobcnik. 1999. Preparation of iodide ion-selective electrode with chemically pretreated silver tube and its suitability in potentiometric flow injection analysis for the determination of vitamin C. Slovenski Kentijski Dnevi 1999 88-93. 

Iodide Ion Selective Electrode To the Uncatalyzed Reaction. Mikrochim. Acta, No. 6, 925 (1973). 29 9828... 

An ion-selective electrode is available for chloride analysis chloride can be measured potentiometrically at 10 -1 M. Iodide and sulfide are the principal interferences. 

Certain ion selective electrodes, such as the iodide and the chloride electrode, permit the assay of minute quantities if the electrode is properly designed for the purpose (20). 

Buchberger et al. [104] carried out a selective determination of iodide in brine. The performance of a potentiometric method using an ion-selective electrode and of liquid chromatography coupled with ultraviolet detection at 230 nm were compared as methods for the determination of iodide in the presence of other iodide species. Satisfactory results were obtained from the potentiometric method provided the solution was first diluted tenfold with 5 M sodium nitrate, and external standards were used. Better reproducibility was, however, achieved with HPLC, provided precautions were taken to prevent reduction of iodine to iodide in the mobile phase, for which extraction of iodine with carbon tetrachloride prior to analysis was recommended. This was the pre-... 

Tecator FIA star 5025 Relatively low cost manual instrument specifically designed for fluoride, cyanide, potassium, iodide, etc. Specially designed for use with ion-selective electrodes... 

Cyanide ion-selective electrode As demonstrated in chapter 3.4, the dissolution of a halide ISE in the presence of some complexing agents, especially cyanide, can be used for determination of these agents [312, 392, 434]. An iodide ISE can be used as a cyanide ISE. The principal application of this electrode is in the determination of cyanides in waters [60, 126, 281, 336] and in galvanic baths [222, 225]. 

In the method proposed by van Staden for the determination of three halides, these are separated in a short colunm packed with a strongly basic ion-exchange resin (Dowex i-X8) that is placed in an FI manifold. A laboratory-made tubular silver/silver halide ion-selective electrode is used as a potentiometric sensor. Van Staden compared the response capabilities of the halide-selective electrodes to a wide concentration range (20-5000 pg/mL) of individual and mixed halide solutions in the presence and absence of the ion-exchange column. By careful selection of appropriate concentrations of the potassixun nitrate carrier/eluent stream to satisfy the requirements of both the ion-exchange column and the halide-selective electrode, he succeeded in separating and determining chloride, bromide and iodide in mixed halide solutions with a detection limit of 5 /xg/mL [130]. 

The potentiometric determination of bromide anions with ion-selective electrodes is possible with commercial electrodes that are commonly based on solid Ag2S—AgBr ion conductor membranes [148-150]. Recently, a novel liquid film sensor has been proposed by Ganjali etal. [151] Determination of bromide was reliable without significant interference from common ions such as chloride and iodide, and was reported down to a micromolar level. The electroactive species in the liquid membrane... 

The determination of iodide with ion-selective electrodes is possible with commercial sensors often based on ion conducting Ag2S—Agl solid membranes [57]. A PVC membrane-based sensor employing a silver complex with thiourea derivatives has been reported by El Aamrani et al. [202]. Interference from thiocyanate and bromide was investigated and a limit of detection in the nanomolar range was determined. A study assessing the performance... 

In measurements with ion-selective electrodes, interference by other ions is expressed by selectivity coefficients as in Eq. (17). If the nature of the ion-selective membrane is known, these interferences may easily be estimated. For example, in the determination of chloride with a Cl -selective electrode containing AgCl as the electroactive component in its membrane, concentrations of bromides or iodides (generally X ) must be controlled because they form less soluble silver salts than AgCl the solubility products of corresponding silver halides are used in Eq. (20) to estimate the selectivity coefficient ... 

Various cells are available for the detection of phosgene. In one example [2093a], the test gas is fed into a solution of potassium iodide, and the liberated iodine reduced at the cathode (c/. Section 3.2.1.2). Ion-selective electrodes have also been adapted for the... 

Several authors investigated ion selective electrodes incorporating GOD coupled with oxidative reactions catalyzed by horseradish peroxidase (HRP). Thus, glucose has been determined by measuring iodide concentration at an iodide sensitive electrode (Nagy at al., 1973) according to ... 

Ion-selective electrodes are used for many applications but most commonly for the measurement of pH and metal ions such as tin , lead silver and nickeT as well as various other analytes such as surfactants". The samples investigated range from surface waters, e.g. lakes and streams, ground waters, rain, to soil and food. ISEs for anion detection are not as prevalent due to solubility issues but more are becoming available, such as one for iodide with a detection limit of 5.3 X 10 and with the help of ionic liquids another has been developed for sulfate detection". 

An advantage or disadvantage, depending on the situation, is that ion-selective electrodes are responsive to a particular chemical form of an element. For example, an iodide electrode responds only to I, not to the total iodine content which could include IOs or organically botmd iodine. 

The application of potentiometric detection in ion-chromatography is favoured by the progress in the field of membrane ion-selective electrodes (ISE). The electrodes with solid-state membranes were mostly employed for determination of halides, pseudohalides and some other anions binding silver ions. The use of fluoride electrode in multidetector, chromatographic system offers very low detection limit of 1.2 ng fluoride in injected samples. Application of bromide electrode in the same system provides even five-fold better detectability. The same level of detectability was reported by Butler and Gershey for iodide with iodide ISE. In the system with preconcentration step the detectability can be lowered by an order... 

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