A. F. Shoukry

Flow injection potentiometric determination of pipazethate hydrochloride

New plastic membrane electrodes for pipazethate hydrochloride based on pipazethatium phosphotungstate, pipazethatium phosphomolybdate and a mixture of the two were prepared. The electrodes were fully characterized in terms of composition, life span, pH and temperature and were then applied to the potentiometric determination of the pipazethate ion in its pure state and pharmaceutical preparations under batch and flow injection conditions. The selectivity of the electrodes towards many inorganic cations, sugars and amino acids was also tested.

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.

Conductimetric determination of reproterol HCl and pipazethate HCl and salbutamol sulphate in their pharmaceutical formulations

A simple and sensitive conductimetric method for the determination of salbutamol sulphate and reproterol and pipazethate hydrochlorides is presented based on their ion associates with phosphotungstic and phosphomolybdic acids. The effect of solvent, molar ratio, reagent concentration and temperature were studied, and the solubility products of the formed ion associates were calculated. The method was applied to the determination of the drugs in their pure state or pharmaceutical preparations with mean recovery values of 99.82-100.54, 99.75-100.12 and 99.95-100.40%, and coefficient of variation 0.28-0.52, 0.16-0.36 and 0.19-0.33 for salbutamol sulphate, reproterol HCl and pipazathate HCl, respectively.

Flow injection potentiometric determination of amantadine HCl.

New amantadine (Am) ion selective plastic membrane electrodes of both conventional and coated graphite types based on the ion-pair of amantadinium tetraphenylborate (Am-TPB) ion-pair are prepared. The conventional type electrode was fully characterized in terms of membrane composition, life span, pH, ionic strength and temperature. It was applied to potentiometric determination of amantadine in pure state and pharmaceutical preparation under batch and flow injection conditions. The selectivity of the electrode toward a large number of inorganic cations, sugars and amino acids was tested. The solubility product of the ion-pair and the formation constant of the precipitation reaction leading to the ion-pair formation were determined conductimetrically.

Spectrophotometric determination of meclozine HCl and papaverine HCl in their pharmaceutical formulations.

A simple, accurate and highly sensitive spectrophotometric method is proposed for the rapid determination of meclozine and papaverine hydrochlorides using chromotrope 2B (C2B) and chromotrope 2R (C2R). The method consists of extracting the formed ion-associates into chloroform in the case of meclozine HCl and into methylene chloride in case of papaverine HCl. The ion-associates exhibit absorption maxima at 536 and 524 nm for C2B and C2R with meclozine HCl and at 540 and 528 nm with papaverine HCl, respectively. Meclozine can be determined up to 4.0 and 2.6 mg ml(-1), using C2B and C2R, respectively, while papaverine can be determined up to 1.68 and 1.37 mg ml(-1), respectively. The effect of acidity, reagent concentration, time, solvent and stoichiometric ratio of the ion-associates were studied. The molar absorptivity and Sandell sensitivity of the reaction products were calculated. The method was applied to the determination of the drugs in their pure state or pharmaceutical preparations with mean recovery values of 99.63-100.80 and 99.75-100.08% and coefficient of variation 0.945-2.210 and 1.020-1.268 for meclozine HCl and papaverine HCl, respectively.

Plastic membrane ion selective electrodes for the determination of some anesthetic compounds

Abstract Lignocaine (LC), procaine (PC), and benzocaine (BC) ion selective electrodes based on incorporation of ion pairs of tetraphenylborate anion (TPB) with protonated LC, PC, and BC in plasticized polyvinyl chloride membranes were prepared. The electrodes showed linear responses with Nernstian slopes over the concentration ranges 3.16 × 10−5–1.25 × 10−2, 1.99 × 10−5–1.60 × 10−2, and 6.31 × 10−6–1.20 × 10−2 M of LC, PC, and BC, respectively. The change in pH did not affect the electrode performance within the ranges 2.0–7.6, 2.9–8.1, and 5.5–8.5 for the three electrodes, respectively. The electrodes were very selective for the respective drugs and exhibited very small isothermal coefficients amounting to 0.00099, 0.00083, and 0.00065 V/deg for LC, PC, and BC electrodes, respectively. Potentiometric titrations were successfully applied to determine LC, PC, and BC using standard TPB solution as titrant and the respective electrodes as potentiometric sensors.

SPECTROPHOTOMETRIC DETERMINATION OF DIPYRIDAMOLE AND CHLORPHENIRAMINE MALEATE USING SOME CHROMOTROPIC ACID AZO DYES

A simple, accurate and highly sensitive spectrophotometric method is proposed for the rapid determination of Dipyridamole using p-chlorophenylazo chromotropic acid (p-Cl) and 2-(p-nitrophenylazo)-chromotropic acid (C2B) and Chlorpheniramine maleate using p-chlorophenylazo chromotropic acid (p-Cl), p-iodophenylazo chromotropic acid (p-I), 2-(p-nitrophenylazo)-chromotropic acid (C2B) and 2-(phenylazo)-chromotropic acid (C2R). The method consists of extracting the ion-associates into methylene chloride. The ion-associates exhibit absorption maxima at 544 and 524 nm for p-Cl and C2B with Dipyridamole, and at 540, 524, 536 and 524 nm for p-Cl, p-I, C2B and C2R with Chlorpheniramine maleate, respectively. Dipyridamole can be determined up to 3.50 and 3.78 mg ml−1 using p-Cl and C2B, respectively, while Chlorpheniramine maleate can be determined up to 3.10, 2.36, 1.90 and 1.70 mg ml−1 using p-Cl, p-I, C2B and C2R, respectively. The stoichiometric ratio of the ion-associates was estimated. The molar absorptivity and Sandell sensitivity of the reaction products were calculated. Statistical treatment of the results reflects that the procedure is precise, accurate and easily applied for the determination of the drugs under investigation in pure form and in their pharmaceutical preparations.

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.

Etilefrine Plastic Membrane Electrodes Based on Individual and Mixed Ion-exchangers of Etilefrinium Phosphotungstate and Tetraphenylborate.

Abstract Etilefrine hydrochloride (EfCl) selective PVC membrane electrodes based on Etilefrinium phosphotungstate (I), Etilefrinium tetraphenylborate (II) and a mixture of both (III) were prepared, The electrodes exhibited near Nernstian response over the concentration ranges 5.0 × 10−6 - 1.0 × 10−1, 6.3 × 10−6 - 1.0 × 10−1 and 6.3 × 10−5 - 1.0 × 10−1 M EfCl for electrodes I, II and III, respectively. The working pH ranges of electrodes I, II and III were 10 - 8.0, 10 - 7.5 and 10 - 7.5 and their isothermal coefficients were 0.00150, 0.00088 and 0.00072 V/°C, respectively. The electrodes showed good selectivity to EfCl with respect to many inorganic cations, sugars and amino acids. The standard additions method was used to determine EfCl in pure solutions and in pharmaceutical preparations.

Spectrophotometric Determination of Lignocaine in Pure Form and in Pharmaceutical Preparations

Abstract Two spectrophotometric methods have been developed for the determination of lignocaine in pure raw material or in formulated dosage form. One of these methods is based on the extraction of the ion-associate formed with reineckate salt by nitrobenzene or chloroform/acetone [solvent mixture, 1:1 (v/v)] and the absorbance is measured at 525 nm and at pH 5. Beers law is obeyed in the range 0.2-2.0 mg/mL. The other method depends on the oxidation of lignocaine by Ce(IV), the excess of Ce(IV) is reacted with chromotrope 2B or chromotrope 2R where the red colour of the reagent decreases. The absorbance is measured at 510 and 530 nm and the methods are found useful in the concentration ranges 0.5-2.5 and 1.1-3.4 μg/mL, respectively. In another approach iron (II) is added to the excess Ce(IV) followed by the reaction with thiocyanate, salicylate or o-phenanthroline. The developed colours are measured at 450, 520 and 510 nm with concentration ranges 1.5-12.3, 1.8-10.6 and 0.5-4.3 μg/mL, respectively. It i...