Sayed S. Badawy

Ion-selective electrode for the determination of metoclopramide

A metoclopramide (MCP) ion-selective PVC membrane electrode based on the ion-pair complex of MCP with sodium tetraphenylborate was prepared with dioctyl phthalate as a plasticiser. The electrode exhibits a linear response with an approximate Nernstian slope (50 mV decade–1 at 20 °C) within the concentration range 10–1.7–10–5.6M MCP. The effects of ionic strength and pH of the test solution on the electrode performance were studied. The electrode exhibited very good selectivity for MCP with respect to a large number of inorganic and organic cations of biological importance. The standard additions method and potentiometric titration were used to determine the MCP in pure solutions and in pharmaceutical preparations with satisfactory results.

Hydralazine-selective PVC membrane electrode based on hydralazinium tetraphenylborate

A hydralazine ion-selective PVC membrane electrode based on hydralazinium tetraphenylborate has been prepared with dioctyl phthalate as plasticizer. The electrode showed linear response with a slope factor of 57.5 mV/concentration decade at 20 degrees over the concentration range from 4 x 10(-4) to 10(-1)M hydralazine. The effects, on the electrode performance, of membrane composition, pH of the test solution and the time of soaking were studied. The electrode exhibited good selectivity for hydralazine with respect to a large number of inorganic cations and organic substances of biological importance. The standard-addition method and potentiometric titrations were used to determine hydralazine concentrations in pure solutions and in a pharmaceutical preparation, with satisfactory results.

Diphenhydramine-sensitive membrane electrodes based on poly(vinylchloride) matrices and their use in drug analysis

Abstract Diphenhydramine hydrochloride-selective electrodes of both the coated wire and the more conventional polymer membrane types have been prepared. They are based on incorporating the diphenhydramine-tetraphenyl borate ion pair in plasticized poly(vinylchloride) film. The performance characteristics are investigated. A Nernstian response is shown by these electrodes within certain concentration ranges depending on the type of electrode. The electrodes are highly selective for diphenhydramine with respect to several inorganic cations, sugars and some amino acids of significant importance in biological fluids and pharmaceutical preparations. Diphenhydramine is determined successfully in pure solutions and in some antihistaminic syrups using the standard additions method and potentiometric titrations.

Structural studies on new diphenyl formazans and their lanthanide(III) complexes

SummaryPotentiometric, u.v., i.r., n.m.r. and t.g.a. studies have been carried out on 1,5-bis(o-carboxyphenyl)-3-acetyl-formazan and 1-(o-carboxyphenyl-5-(o-hydroxyphenyl)-3-acetylformazan and their complexes with trivalent lanthanide ions. The ionization constants of formazans and the formation constants of their complexes have been determined potentiometrically by the Bjerrum-Calvin method (Irving and Rossotti modification). Complexation has also been studied by a conductimetric titration method.

Thermogravimetric studies on lanthanide complexes of new derivatives of 1,5-diaryl-3-acetylformazan

Abstract Solid complexes of two new derivatives of 1,5-diaryl-3-acetylformazan with lanthanide metal ions were prepared and characterized by elemental and thermogravimetric analyses. The suggested formula of the complexes is ML 2 (H 2 O) x · y H 2 O where L = formazan, x = 0–2, y = 1–4 and M = trivalent lanthanide ion. Information about the water of hydration, the coordination chemistry and the thermal stability of these complexes was obtained. A general mechanism for the thermal decomposition of the complexes is suggested. A coordination number of ten is proposed for the lanthanide ions in these complexes which decreases from La to Lu due to the lanthanide contraction.

PVC Membrane electrode for trinitrobenzenesulfonate and its use for indirect determination of amino acids

A PVC membrane electrode of the conventional type was prepared which is selective for trinitrobenzenesulfonate (TNBS−). It showed a rapid Nernstian response within the TNBS− concentration range 1.0 × 10−5 to 1.0 × 10−2M at 25 ± 0.1°C. The electrode was selective, precise (RSD < 0.87% for TNBS− and < 1.32% for amino acids) and usable within the pH range 2.5–12. The standard electrode potentials,E°, were determined at different temperatures and used to calculate the isothermal temperature coefficient of the cell. Selectivity coefficients for numerous compounds are given. The electrode has been used for the direct determination of trinitrobenzenesulfonic acid in aqueous solutions either by the standard additions method or by potentiometric titration against cetyltrimethylammonium bromide (CTABr) at pH 7. The electrode has been also applied successfully for the indirect microdetermination of neutral, acidic and basic amino acids separately, and as binary or ternary mixtures of neutral amino-acids. Total amino acids were determined in urine samples.