Determination of ionization constants of monobasic acids in ethanol-water solvents by direct potentiometry

1968 ◽  
Vol 40 (10) ◽  
pp. 1408-1411 ◽  
Author(s):  
J. O. Frohliger ◽  
R. A. Gartska ◽  
H. W. Irwin ◽  
O. W. Stewward
Keyword(s):  
Ionization Constants ◽  
Direct Potentiometry

scholarly journals Influence of Erythrocytes on Direct Potentiometric Determination of Sodium and Potassium

1983 ◽  
Vol 20 (2) ◽  
pp. 116-120 ◽  
Author(s):  
P Bijster ◽  
H L Vader ◽  
C L J Vink
Keyword(s):  
Whole Blood ◽  
Potassium Concentration ◽  
Reference Electrode ◽  
Sodium Concentration ◽  
General Phenomenon ◽  
Liquid Junction ◽  
Direct Potentiometry ◽  
The Difference ◽  
Sodium And Potassium

We have shown that the sodium concentration in whole blood measured by direct potentiometry is higher than in plasma. The ‘erythrocyte-effect’, already described by Siggaard Andersen, is most pronounced for instruments equipped with a reference electrode with an open static liquid junction and is thus a general phenomenon. Instruments with a modified liquid junction show less interference. The same phenomenon appears for the determination of the potassium concentration, although the difference between whole blood and plasma, when measured with instruments equipped with a modified liquid junction, can be neglected in practice.

Ektachem Slides for Direct Potentiometric Determination of Sodium in Plasma: Effect of Natremia, Blood pH, and Type of Electrolyte Reference Fluid on Concordance with Flame Photometry and Other Potentiometric Methods

1992 ◽  
Vol 38 (1) ◽  
pp. 114-118 ◽  
Author(s):  
Ann Boeyckens ◽  
Jan Schots ◽  
Hugo Vandenplas ◽  
Freedy Senesael ◽  
Wim Goedhuys ◽  
...  
Keyword(s):  
Gastrointestinal Disease ◽  
Flame Photometry ◽  
Direct Potentiometry ◽  
Blood Ph ◽  
Ph Dependency ◽  
Analytical Recovery ◽  
The One

Abstract With electrolyte reference fluid (ERF)00, results from Kodak Ektachem slides for the direct potentiometric assay of sodium in plasma were significantly correlated with results from flame photometry, but also appeared to be systematically higher, especially in hypernatremic patients. Indirect potentiometry with the Technicon RA-1000 yielded intermediate values. In 23 hypernatremic patients with greater than or equal to 6 mmol/L difference in sodium between Ektachem ERF00 and flame photometry, a clinical survey disclosed the frequent association of large between-method differences with renal failure, diabetes mellitus, and gastrointestinal disease. However, there was no correlation between differences in sodium on the one hand and anion gaps or (lipo)protein concentrations on the other, nor did in vitro addition studies implicate metabolites that often accumulate in the above-mentioned disorders. Unlike indirect methods, sodium measurements by direct potentiometry on Ektachem and Corning were influenced by in vitro changes of pH between 7.0 and 7.9. However, in a group of patients that included many acidotic individuals, between-method differences in sodium appeared not significantly correlated with in vivo blood pH. Use of the equitransferant ERF04 on Ektachem strongly diminishes the systematic differences with flame photometry, reduces the pH-dependency of the results to that of the direct Corning method, and brings the mean analytical recovery of sodium to below 95% (instead of 115% previously) without affecting the ability of Ektachem slides to avoid spuriously low results in the presence of increased (monoclonal) protein concentrations.

scholarly journals Preparation, Characterization, and Analytical Application of Ramipril Membrane-Based Ion-Selective Electrode

2009 ◽  
Vol 2009 ◽  
pp. 1-7 ◽  
Author(s):  
Hassan Arida ◽  
Mona Ahmed ◽  
Abdallah Ali
Keyword(s):  
Pharmaceutical Formulations ◽  
Ion Pair ◽  
Pvc Membrane ◽  
Ion Selective Electrodes ◽  
Selective Electrode ◽  
Response Sensitivity ◽  
Direct Potentiometry ◽  
Plasticized Pvc ◽  
Electrochemical Evaluation

The fabrication and electrochemical evaluation of two PVC membrane-based Ion-Selective electrodes responsive for ramipril drug have been proposed. The sensitive membranes were prepared using ramipril-phosphomolibdate and ramipril-tetraphenylborate ion-pair complexes as electroactive sensing materials in plasticized PVC support. The electrodes based on these materials provide near-Nernestian response (sensitivity of53±0.5–54±0.5 mV/concentration decade) covering the concentration range of1.0×10-2–1.0×10-5 molL−1with a detection limit of3.0×10-6–4.0×10-6 molL−1. The suggested electrodes have been successfully used in the determination of ramipril drug in some pharmaceutical formulations using direct potentiometry with average recovery of >96% and mean standard deviation of <3% (n=5).

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