In the previous communication (l), it was shown that the free energy of the bivalent fumarate ion at 25” is -144,630 calories. In the present communication the measurement of the equilibrium at 25” between fumaric acid and malic acid in the presence of fumarase is reported, and from the values obtained computations are made of the free energy and heat of formation of the bivalent I-malate ion a...

Direct drug determination without any pervious treatment steps is the most environmentally friendly method of analysis. Traditional analysis methods usually involve a pre-treatment step before analysis and this consumes time and organic solvents. This work describes direct potentiometric method by using ion selective electrode to determine Montelukast Sodium in its pure drug substance and in ta...

Electrodes for scanning ion-selective potentiometric microscopy (or potentiometric SECM) were developed and used to image local concentration profiles of NH4+, K+, and Zn2' ions. Neutral carrier-based micropipet ionselective electrodes with high spatial resolution (-2-3 pm) and fast response time (-300 ms) were fabricated and employed as potentiometric SECM tips, and highresolution ion-selectiv...

This study compares between unmodified carbon paste (CPE; the paste has no ion pair) and polyvinyl chloride (PVC) membrane selective electrodes that were used in potentiometric determination of ketotifen fumarate (KTF), where sodium tetraphenylborate (NaTPB) was used as titrant. The performance characteristics of these sensors were evaluated according to IUPAC recommendations which reveal a fas...

and 2.0% for patients’ samples having mean total CO2 of 7 and 35 mmol/L, respectively (n = 27). Least-squares linear-regression analysis of the total CO2 values obtained from the potentiometric (x) and new enzymatic slides (y) for 113 clinical samples (range 15-41 mmol/L) showed the following relationship: y = 0.92 x + 0.35 (r = 0.976, P <0.01) (4). Only samples assayed within 5 miii of each ot...

Dithiodibenzoic (DTB) acid and mercaptobenzoic (MB) acid were studied to characterize their abilities as modifier agents for lead(II) sensors. For both sensors, the best results were obtained with modified carbon paste electrodes with 24.1% of ligand. The pH influence on the potentiometric response was studied. The selectivity coefficients for both modified electrodes were tabulated. A potentio...

The protonation constants of new group of peptidomimetic cyclophanes with valine or phenylalanine moieties incorporated into the macrocyclic skeleton as well as their linear analogues were determined by potentiometric measurements in solutions of methanol-water mixtures at 25°C and constant ionic strength. The influence of cavity size, location of protonation sites, and attached substituents of...

A new automatic potentiometric reaction-rate method has been applied to the specific enzymatic measurement of glucose in blood plasma or serum. A new filtering technic is described for removal of precipitated protein. The use of injection pipets to simplify and speed up the reagentand sample-handling step is described. Glucose is determined in 0.02 ml. of serum or plasma with relative errors wi...