Thiocyanate-Selective Membrane Electrode Based on (Octabromotetraphenylporphyrinato)manganese(III) Chloride

Abstract

The response characteristics of a new solvent-polymeric membrane electrode with unique selectivity and detection limit toward SCN À ion are reported. The electrode is prepared by incorporating (octabromotetraphenylporphyrinato)manganese(III) chloride into a plasticized PVC-membrane. The resulting sensor exhibits anti-Hofmeister selectivity pattern with high speci®city for thiocyanate over other anions, including lipophilic inorganic anions. The electrode has a linear dynamic range between 1.0 and 4.8610 À7 M, with a Nernstian slope of 58.3 AE 0.8 mVadecade and a detection limit of 3.2610 À7 M. The electrode can be used for at least 3 months without any considerable divergence in potential. It was used as an indicator electrode in potentiometric titration of SCN À ion and in direct determination of thiocyanate in urine samples.

A New Selective Membrane Electrode for Oxalate Based on N,N'-Bis(salicylidene)-2,2-dimethylpropane-1,3-diamine Ni(II)

“…It is well known that the sensitivity, linearity and selectivity, obtained for a given ionophore, depends significantly on the membrane composition, nature and the amount of additive used. 2,[27][28][29][30][31] The percentage of membrane solvent in poly (vinyl chloride) membranes and the membrane solutions for micro-electrodes is very high (60-90 wt.%). Hence, the membrane solvent has to exhibit excellent plasticizer properties for use in solvent polymeric membranes.…”

Iodide-selective membrane electrode based on salophen complex of cobalt (III)

“…In the case of ionophores based on different metal ion complex, in addition to the electrostatic interaction between the central metal ion and analyte anions, there is a coordination action between both species involved. [10][11][12][13][14][15][16][17][18][19][20][21][22][23] Thus, the selectivity sequence is dominated by both electrostatic and coordination forces and it is expected that both the nature of the complexed metal ion and the coordination ligand properties play important roles in determining the selectivity of the ionophore towards a specific anion. Recently, there have been a few reports on ionophores that when introduced into solvent polymeric membranes bring about iodide selectivity very divergent from the Hofmeister series.…”

“…Soc. metallophthalocyanines [14][15][16][17] and some lipophilic organometallic compounds, [17][18][19][20][21][22][23] which show anion selectivity in the membranes that differ from the Hofmeister selectivity sequence. The observed anti-Hofmeister behavior arises from a strong interaction between anions and the ionophores used.…”

Charge-Transfer Triiodide Ion-Selective Electrode Based on 7,16-Dibenzyl-1,4,10,13-tetraoxa-7,16-diazacyclooctadecane

“…10,25 The sensor material with DBP, AP or DMS as a plasticizer and PVC were dissolved in 2 ml of THF. The resulting mixture was transferred into a glass dish of 2 cm diameter.…”

“…[1][2][3] The key ingredient of such plasticized PVC membranes is the incorporated carrier, which defines the selectivity of the electrodes via selective complex formation with the anion of interest. Among different anion carriers used for this purpose, 4 the use of metalloporphyrins, [5][6][7][8][9][10] metal complexes, 11,12 and organometalic compounds 13,14 as ionophores in solvent polymeric membrane electrodes are well known to induce potentiometric anion selectivity sequences that differ significantly from the classical Hofmeister pattern. [5][6][7][8][9][10][11][12][13][14] Despite the need for a triiodide ion-selective electrode for the determination of iodide and triiodide ion in many medical, 17,18 juice (as ascorbic acid in orange juice) 20 and environmental samples (such as dissolved O2 in water), [15][16][17][18][19][20][21][22][23] to date there have been limited reports on an I3 -ion-selective electrode in the literature.…”