Mahmoud S. Rizk

Salbutamol plastic membrane electrodes based onindividual and mixed ion-exchangers of salbutamolium phosphotungstate andphosphomolybdate

Salbutamol (Sl), also known as albuterol, selective PVC membranes based on ion associates of salbutamolium phosphotungstate (Sl-PTA), salbutamolium phosphomolybdate (Sl-PMA) or a mixture of both (Sl-PTA/PMA) were prepared. The electrodes displayed a linear response over the concentration range 6.3 × 10−6–1.0 × 10−1 mol dm−3 salbutamol sulfate (Sl2SO4). The working pH ranges of the above electrodes were 2.5–11.0, 3.0–11.0 and 2.5–10.5 and their isothermal temperature coefficients were 0.00095, 0.00105 and 0.00136 V °C−1, respectively. The electrodes showed good selectivity to salbutamolium ion with respect to many inorganic cations, sugars and amino acids. The standard additions method was used to determine Sl2SO4 in pure solutions and pharmaceutical preparations with high accuracy and precision.

A New Metformin Selective Plastic Membrane Electrode Based on Metformin Tetraphenylborate

Abstract A new metformin (Mf) ion selective PVC membrane electrode based on the ion-pair complex of Mf with sodium tetraphenylborate was prepared and its performance characteristics were studied. The electrode exhibited a linear response with a good Nernstian slope over a relatively wide range of concentration. The calibration graph slope was constant for up to 14 days with continuous soaking at 54 mv/ concentration decade at 30°C. Then the slope decreased as the time of soaking increased, reaching 42 mv/decade after 21 days. The changes in pH did not affect the electrode performance within the range 4.0–11.0. The standard electrode potentials were determined at different temperatures and were used to calculate the isothermal coefficient of the electrode (0.0004 V/°C). The electrode showed a very good selectivity for Mf with respect to a large number of inorganic and organic cations. The standard addition method and potentiometric titration were used to determine Mf in pure solutions and in pharmaceutical...

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.

Development of two reference materials for all trans-retinol, retinyl palmitate, α- and γ-tocopherol in milk powder and infant formula

Vitamins are important food constituents that can be present in almost every foodstuff. Food quality and safety depends on food surveillance by reliable quantitative analysis enabled by appropriate quality control. Certified matrix reference materials are versatile tools to support quality assurance and control. However, in the case of vitamins, which are important in various foods, there is a lack of matrix reference materials. Two certified reference materials for the determination of all-trans-retinol, retinyl palmitate, and α- and γ-tocopherol in milk powder and infant formula have been developed by the National Institute of Standards, Egypt. This article presents the preparation, characterization, homogeneity, and stability testing as well as statistical treatment of data and certified value assignment. The assignment of the certified values and associated uncertainties in the prepared natural-matrix reference materials were based on the widely used approach of combining data from independent and reliable analytical methods.

Potentiometric flow injection determination of salbutamol

ABSTRACT Potentiometric detection of salbutamol sulphate Sl2SO4 using electrodes containing its ion-exchangers with phosphotungstic; phosphomolybdic acid or a mixture of both was applied in flow injection systems in the Nernastian range of the electrodes response. The selectivity of these electrodes towards different cations was studied in comparison to that obtained in batch conditions. The method was then used to determine the drug in its 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...

Flow-injection potentiometric and conductometric determination of papaverine hydrochloride in the parent substance and a related pharmaceutical preparation

Papaverine (Pap) ion-selective plastic membrane electrodes based on ion associates of papaverine with phosphotungstic acid (Pap-PTA) and phosphomolybdic acid (Pap-PMA) were prepared and fully characterized in terms of membrane composition, life span, pH, and temperature. The proposed electrodes were applied to potentiometeric determination of papaverine in the parent substance and a related pharmaceutical preparation under batch and flow-injection analysis conditions. In addition, conductometric titrations were used for the assay of papaverine in the parent substance and the related pharmaceutical preparation. The selectivity of electrodes with respect to a large number of foreign inorganic cations, amino acids, and sugars was tested. The solubility product of the ion associate and the rate constant of the precipitation reaction leading to the ion associate formation were determined conductometrically.

New Ampicillin Selective Plastic Membrane and Coated Metal Electrodes Based on Ampicillinium Phosphotungstate Ion pair.

Abstract A new ampicillin (Amp) ion-selective PVC membrane electrode based on the ion pair complex of Amp with phosphotungstic acid is prepared and its performance characteristics are studied. The electrode exhibited a linear response with a good Nernstian slope over a relatively wide range of concentration (1.6 × 10−4 - 4.0 × 10−2 M). Up to 10 h. continuous soaking, the calibration graph slope is constant at about 59 mV/concentration decade, at 25°C, then it decreases gradually as the time of soaking increases, reaching 42.5 mV/concentration decade after 42 days. The changes in pH do not affect the electrode performance within the range 3–11. The isothermal coefficient of the electrode was 0.00184 V/°C. The electrode showed very good selectivity for Amp in presence of a large number of inorganic and organic cations. The standard addition method and potentiometric titration are used to determine Amp in pure solutions and in pharmaceutical preparations. Coated wire electrodes are made using Cu, Cu/CuS, Pt,...

Extraction-spectrophotometric determination of amprolium hydrochloride using bromocresol green, bromophenol blue and bromothymol blue

A new procedure for the determination of amprolium hydrochloride by reaction with bromocresol green (BCG), bromophenol blue (BPB) and bromothymol blue (BTB) has been developed. The method consists of extracting the yellow ion-pair formed into chloroform from aqueous medium. The ion-pairs have absorption maxima at 420, 410 and 415 nm with molar absorptivities of 3.64 × 104, 3.12 × 104 and 2.31 × 1041 mol−1 cm−1 for BCG, BPB and BTB, respectively. The method obeys Beers law over the concentration ranges 0.6–12.0, 0.12–8.8 and 1.2–11.3 νag/ml amprolium hydrochloride for BCG, BPB and BTB, respectively. The method is simple, precise (relative standard deviation 0.665–2.210%), accurate (recovery 97.8–100.8%) and easily applied for pharmaceutical quality assurance for amprolium hydrochloride in raw materials and in formulated veterinary soluble powder.

Plastic membrane electrodes for amprolium

The construction and general performance characteristics of two PVC membrane sensors responsive to the amprolium (AmpH2+) cation are described. These sensors are based on the ion-associates amprolium-tetraphenylborate (AmpH-TPB) and amprolium-reineckate (AmpH-Rk). The electrodes exhibit near-Nernstian response for the doubly charged amprolium cation over the concentration ranges 0.1–100 and 0.01–100 mM for AmpH-TPB and AmpH-Rk, respectively. The pH does not affect electrode performance within the range 7.0–11.0. No interferences are caused by many inorganic cations, sugars and amino acids. The isothermal coefficients are found to be 0.0001306 and 0.0010438 V/ °C for AmpH-TPB and AmpH-Rk, respectively. Potentiometric titration and standard addition methods were used to determine amprolium in pure solutions and in veterinary soluble powder, with high accuracy and precision.