Inorganic anions, potentiometric

Electrochemical detectors measure the current resulting from the application of a potential (voltage) across electrodes in a flow cell. They respond to substances that are either oxidizable or reducible and may be used for the detection of compounds such as catecholamines, carboxylic acids, sulfonic acids, phosphonic acids, alcohols, glycols, aldehydes, carbohydrates, amines, and many other sulfur-containing species and inorganic anions and cations. Potentiometric, amperometric, and conductivity detectors are all classified as electrochemical detectors. 

Sulfa drug sensitive electrodes have been used for the potentiometric titration of sulfonamides using standard sulfuric acid solution as titrant with distinct potential jump at the equivalence point and a maximum error of 0.7%. No significant interference is caused by the common inorganic anions (69). Ion-pair complexes of sulfa drugs and quaternary ammonium agents such as cetyltrioctylammonium have been employed as membrane electrodes for the potentiometric determination of sulfonamides (70). 

P. R. Haddad, P. W. Alexander, and M. Trojanowicz, Ion chromatography of inorganic anions with potentiometric detection using a metallic copper electrode, /. Chromaiogr., 321,363,1985. 

Umezawa. Y. Umezawa. K. Biihlmann. P. Hamada. N. Nakanishi, J. Aoki, H. Sato, M. Nishimura, Y. Xiao. K.P. Potentiometric selectivity coefficients of on-selective electrodes. Part II. Inorganic anions. Pure Appl. Chem. 2002, 74. 923-994. 

PPy is known to exhibit anionic or cationic potentiometric responses depending on the doping ion. PPy films doped with mobile inorganic anions show anionic sensitivity, while PPy films doped with anions of low mobility such as sulfate, large organic anions, or polyanions show cationic sensitivity. This bifunctionality of ionic and redox sensitivity makes PPy apphcable as an all-sohd-state, ion-selective electrode. All-solid-state, potentiometric PPy sensors were developed for potassium and sodium sensing, which showed better response time, selectivity and most importantly long-term stabihty than the coated wire electrode [130]. 

Umezawa Y, Umezawa K, Bublmann P, Hamada N, Aoki H, Nakanisbi J, Moritosbi S, Xia KP, and Nishimura Y (2002) Potentiometric selectivity coefficients of ion-selective electrodes. Part II. Inorganic anions. lUPAC, Pure and Applied Chemistry 74 923-994. 

Gupta V (2010) Potentiometric sensors for inorganic anions based on neutral carriers-an invited review article. Arab J Sci Eng 35(2A) 7-25, 10... 

Compared with separation-based techniques, potentiome-try is a difficult technique to use to detect multiple analytes because of the selectivity of the ion-selective electrode. Because of the influence of the separation voltage, it is difficult to measure the response of the electrode potential, which is correlated logarithmically to the concentration of analyte it has not yet been employed with microchip CE. Potentiometric detection has found application in conventional CE. Kappes and Hauser have fabricated a universal potentiometric sensor for CE by coating wire electrodes with a solid PVC membrane [10]. The sensor was of approximately the same diameter as the outside of the capillary and located at a distance of about 50 p.m from the capillary outlet. A reference electrode was located beside the detection electrode. These coated-wire electrodes with PVC membranes have been employed to determine alkali and alkaline earth metals, small inorganic anions, and lipophilic organic ions such... 

Gldd PK, Haddad PR, Alexander PW (1992) Potentiometric detection of carboxylic acids and inorganic anions in ion-exclusion chromatography using camphor sulphonic acid as... 

An alternative approach for construction of solid contact electrodes can be also applied by casting the sensitive membrane directly oti the surface of a conductor such as silver or a conductive carbon resin. Thus, two surfactant sensors were prepared using hyamine 1622 or tetradodecylammonium (TDA) as catimiic and DBS as anionic surfactant.The sensing materials were incorporated in a PVC matrix containing o-NPOE as a solvent mediator and applied on a support of a conductive resin without inner reference solution. The responses of these electrodes to DS and DBS as well as the interferences of several common inorganic anions and anionic surfactants were examined. The membranes showed good performance for use as a general potentiometric sensor responsive to anionic surfactants. 

The main group duster chemistry discussed in this book can be considered to originate from two important, but apparently unrelated developments in inorganic chemistry in the 1930s. The first was the identification of the neutral boron hydrides by Stock [1]. The second was the observation by Zintl and co-workers [2-5] of anionic clusters formed from potentiometric titrations of post-transition metals (i.e., heavy main group elements) with sodium in liquid ammonia. 

A novel capillary electrophoresis method using solutions of non-crosslinked PDADMAC is reported to be effective in the separation of biomolecules [211]. Soil studies conducted with PDADMAC report the minimization of run-off and erosion of selected types of soils [212]. In similar studies, PDADMAC has found to be a good soil conditioner [213]. The use of PDADMAC for the simultaneous determination of inorganic ions and chelates in the kinetic differentiation-mode capillary electrophoresis is reported by Krokhin [214]. Protein multilayer assemblies have been reported with the alternate adsorption of oppositely charged polyions including PDADMAC. Temperature-sensitive flocculants have been prepared based on n-isopropylacrylamide and DADMAC copolymers [215]. A potentiometric titration method for the determination of anionic polyelectrolytes has been developed with the use of PDADMAC, a marker ion and a plastic membrane. The end-point is detected as a sharp potential change due to the rapid decrease in the concentration of the marker due to its association with PDADMAC [216]. 

PPY is a very well known conducting polymer used in numerous works as the electroactive component of an all-solid-state ISE. Most of the papers dealt with a PPY-coated PVC electrode where PPY is doped with different anions, inorganic such as chloride or organic such as dodecyl sulphate. Several techniques were used to characterize these devices. Potentiometric measurements represent a method allowing thermodynamic characterization. AC electrogravimetry was also used to characterize ion and solvent motions at the PVC/electrolyte interface to imderstand how the electroactive film (Prussian blue, conducting polymer, etc.) ensures the mediation between the membrane and the electrode. ... 

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