Glass Electrodes for Other Cations

Liquid-membrane-type ISEs, based on water-immiscible liquid substances impregnated in a polymeric membrane, are widely used for direct potentio- 

1 Ion Exchanger Electrodes One of the most successful liquid membrane electrodes is selective toward calcium. Such an electrode relies on the ability of phosphate ions to form stable complexes with the calcium ion. It uses a liquid cation exchanger, consisting of an aliphatic diester of phosphoric acid 

Calcium activities as low as 5 x 10 7 M can be measured, with selectivity coefficients of AlCa,Mg and KCa,k of 0.02 and 0.001, respectively. Such potential response is independent of the pH over the pH range 5.5-11.0. Above pH 11, Ca(OH)+ is formed, while below 5.5, protons interfere. Because of its attractive response characteristics, the calcium ISE has proved to be a valuable tool for the determination of calcium ion activity in various biological fluids. 

Anion exchangers, such as lipophilic quaternary ammonium salts (e.g., see Fig. 5.11) or phosphonium salts, have been employed for the preparation of 

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G. Eisenman, ed.. Glass Electrodes for Hydrogen and Other Cations, Marcel Dekker, New York, 1967. 

Bates, R. G. Determination of pH Theory and Practice, New York, Wiley 1964 Eisenman, G., ed. Glass Electrodes for Hydrogen and Other Cations-Principles and Practice, New York, Dekker 1967... 

Glass Electrodes for the Determination of Cations Other Than Hydrogen... 

Glass Electrodes for Hydrogen and Other Cations Prirtciples and Practice... 

N. Khuri, Glass Microelectrodes and their Uses in Biological Systems, in Glass Electrodes for Hydrogen and other Cations (ed. G. Eisenman),... 

Truesdell, A. H., Christ, C. L. In Glass electrodes for hydrogen and other cations (Eisenman, G., ed.). New York Marcel Dekker 1967. 

Ion solvation has been studied extensively by potentiometry [28, 31]. Among the potentiometric indicator electrodes used as sensors for ion solvation are metal and metal amalgam electrodes for the relevant metal ions, pH glass electrodes and pH-ISFETs for H+ (see Fig. 6.8), univalent cation-sensitive glass electrodes for alkali metal ions, a CuS solid-membrane electrode for Cu2+, an LaF3-based fluoride electrode for l , and some other ISEs. So far, method (2) has been employed most often. The advantage of potentiometry is that the number and the variety of target ions increase by the use of ISEs. 

Truesdell, A. and Christ, C., Glass electrodes for calcium and other divalent cations, p. 293-322, in Eisenman, G., ed., "Glass Electrodes for Hydrogen and Other Cations," Marcel Dekker, Inc., New York, 1967. Reuter, J. and Perdue, E. Importance of heavy metal-organic matter interactions in natural waters, Geochim. Cosmochim. Acta 41, 325-244 (1977). 

Eisenman, G., Particular properties of catkm-selective ass electrodes containing AI2O3. In Glass Electrodes for Hydrogen and Other Cations (G. Eisenman, ed.), pp. 268-283. Dekker, New York, 1967. 

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