Sulfate-selective electrode and its application for sulfate determination in aqueous solutions

2006 ◽  
Vol 562 (2) ◽  
pp. 216-222 ◽  
Author(s):  
S.V. Lomako ◽  
R.I. Astapovich ◽  
O.V. Nozdrin-Plotnitskaya ◽  
T.E. Pavlova ◽  
Shi Lei ◽  
...  
Keyword(s):  
Aqueous Solutions ◽  
Selective Electrode ◽  
Sulfate Determination

Association of benflurone in aqueous solutions studied by measuring the activity of chloride ions

1986 ◽  
Vol 51 (11) ◽  
pp. 2437-2443
Author(s):  
František Kopecký ◽  
Mária Vojteková ◽  
Milan Pešák
Keyword(s):  
Aqueous Solutions ◽  
Chloride Ions ◽  
Ion Selective Electrode ◽  
Selective Electrode ◽  
Measured Range

The conventional activity of chloride ions was measured by an ion-selective electrode at 25 °C in aqueous solutions of benflurone, i.e. 5-(2-(N,N-dimethylamino)ethoxy)-7-oxo-7H-benzo(c)fluorene hydrochloride, without or with additions of KCl. These results suggest a gradual association of benflurone; the formation of a hetero-associate, (BH+)2Cl-, followed by higher associates was evaluated in the measured range up to 0.1 mol l-1.

Characterization procedure for ion-selective electrode assays of magnesium activity in aqueous solutions of physiological composition

1993 ◽  
Vol 39 (5) ◽  
pp. 855-859 ◽  
Author(s):  
R Eugster ◽  
B Rusterholz ◽  
A Schmid ◽  
U E Spichiger ◽  
W Simon
Keyword(s):  
Aqueous Solutions ◽  
Liquid Membrane ◽  
Selectivity Coefficient ◽  
Membrane Electrode ◽  
Membrane Composition ◽  
Selective Electrode ◽  
Serum Samples ◽  
Average Deviation ◽  
Characterization Procedure ◽  
Liquid Membrane Electrode

Abstract A magnesium ion-selective liquid membrane electrode based on a synthetic neutral carrier is presented. The selectivity for Mg2+ over Na+, K+, and H+ is sufficient for assays in the physiological range, but a chemometric correction of approximately 10% is still necessary for the Ca2+ interference. We optimized the membrane composition especially with respect to selectivity and accuracy by performing a new characterization procedure in which we simulated the variety of blood serum samples with 10 aqueous solutions. After a three-point calibration, these solutions were measured alternately with the middlerange calibrator for 3 min. The magnesium activity was evaluated after correcting for the calcium interference according to the Nikolsky equation. The selectivity coefficient, KpotMgCa, was itself fitted to give the minimum deviations from the assigned magnesium activities. Electrodes with an optimized membrane composition show an average deviation from theoretical activity values of about 1.6% with logKpotMgCa = -0.8.

Potentiometric Investigation of the Weak Association of Sodium and Oxalate Ions in Aqueous Solutions at 25°C

2005 ◽  
Vol 58 (3) ◽  
pp. 213 ◽  
Author(s):  
Andrew Tromans ◽  
Glenn Hefter ◽  
Peter M. May
Keyword(s):  
Ionic Strength ◽  
Aqueous Solutions ◽  
Infinite Dilution ◽  
Formation Constant ◽  
Ion Pair ◽  
Ion Selective Electrode ◽  
Selective Electrode ◽  
Weak Association ◽  
Tetramethylammonium Chloride ◽  
Good Agreement

The formation constant β(NaOx−) of the extremely weak ion pair formed between sodium (Na+) and oxalate (Ox2−) ions in aqueous solutions has been determined at 25°C as a function of ionic strength in tetramethylammonium chloride by Na+ ion-selective electrode potentiometry. The effects of trace Na+ impurities from all reagents were accounted for. An extrapolated value for β o of 6.6 ± 0.5 M−1 was obtained at infinite dilution, which is in good agreement with literature values. Attempts to measure this constant in 1 M CsCl media gave a β(NaOx−) value of 0.00 ± 0.06 M−1, probably because of competition between Cs+ and Na+ for Ox2−.

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