Azza M. M. Ali

Adsorptive Stripping Voltammetric Determination of Tetracycline and Oxytetracycline

Abstract A sensitive voltammetric method is developed for the quantitation of the antibiotics tetracycline and oxytetracycline (Terramycin). The method is based on controlled adsorptive preconcentration of the antibiotic on the hanging mercury drop electrode (HMDE), followed by tracing the voltammogram in a cathodic potential scan. The modes used are direct current stripping voltammetry (DCSV) and differential pulse stripping voltammetry (DPSV). The adsorptive stripping response was evaluated with respect to preconcentration time and potential, concentration dependence and composition of supporting electrolyte. The detection limits found were 5 × 10−8 (2 min. preconcentration) by DPSV and 1 × 10−7M (10 sec.) by DCSV. These values correspond to 25 and 50 ppb respectively. The relative standard deviation (at 1 × 10−7M level) is 1.4%. Successful applications of the method to analysis of urine and pharmaceutical formulations as capsules or ampules, are described.

Potentiometric studies on the complexes of tetracycline (TC) and oxytetracyclin (OTC) with some metal ions

SummaryThe interaction of Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Zn(II), Cd(II), Hg(II), Pb(II), Al(III), and UO2(II) ions with tetracycline (TC) were studied by potentiometricpH titrations. The formation constants of the different binary complexes formed in such systems have been determined at 25±0.1°C and μ=0.1 moll−1 (NaNO3). PotentiometricpH equilibrium measurements have been made under the same conditions for the interaction of oxytetracycline (OTC) and Cu(II), Cd(II), Pb(II), and UO2(II). The formation of (1:1) binary complexes are inferred from the potentiometricpH tritration curves. The protonation constants ofTC andOTC were also determined under the same conditions and refined (ESAB2M computer program). The transition metal stability constants are consistent with the Irving-Williams series.ZusammenfassungDie Wechselwirkungen von Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Zn(II), Cd(II), Hg(II), Pb(II), Al(III) und UO2(II) Ionen mit Tetracyclin (TC) wurden mittels potentiometrischerpH-Titrationen untersucht. Die Komplexbildungskonstanten wurden bei 25±0.1°C und μ=0.1 mol/1(NaNO3) bestimmt. Unter den gleichen Bedingungen wurden die Komplexierung von Cu(II), Cd(II), Pb(II) und UO2(II) mit Oxytetracyclin (OTC) mittel potentiometrischerpH Gleichgewichtsmessungen untersucht. Aus den potentiometrischenpH-Titrationskurven ergab sich die Bildung von (1:1) binären Komplexen. Die Protonierungskonstanten vonTC undOTC wurden ebenfalls bestimmt und rechnerisch verfeinert (ESAB2M Computer Programm). Die Stabilitätskonstanten für die Übergangsmetalle stimmen mit der Irving-Williams Reihe überein.

Cathodic adsorptive stripping voltammetric determination of the anti-inflammatory drug indomethacin

Sensitive voltammetric methods have been developed for the determination of the anti-inflammatory, anti-pyretic and analgesic drug indomethacin sodium. The methods are based on the controlled adsorptive preconcentration of the drug on a hanging mercury drop electrode (HMDE), followed by tracing the voltammogram in a cathodic potential scan. The modes used are cyclic voltammetry (CV), cathodic stripping voltammetry (CSV) and differential pulse stripping voltammetry (DPSV). Amounts as low as 10 nM (10 ng x ml(-1)) (60 s preconcentration) by CSV and 0.5 microM (190 ng x ml(-1)) (300 s) by DPSV can be determined accurately. The R.S.D. at the 1 x 10(-6) M level is 1.4%. The interference of some metal ions and the application of the method to analysis of urine, plasma and pharmaceutical formulations are described.

Electroanalytical Studies of Azo Sulpha Drugs, Application to Novel Heterocyclo-Sulphonamide Azo Dye

Abstract Cyclic voltammetry has been applied for studying the cathodic reduction behaviour of 3-azo-[4-(diazin-2-yl)-benzene- sulphonamido-] -1-oxa-4-thia-spiro (4,5) decan-2-one sodium salt, as azo dye sulpha drug at the hanging mercury electrode in different supporting electrolytes, i.e. perchlorate, acetic acid-acetate buffer, nitrate and phosphate, at different pH values ranged from (1–11) and different ionic strengths (0.01–0.15). The two related compounds for the sodium salt of azo dye sulpha drug have been also studied at 0.1 M acetic acid- sodium acetate buffer (pH ∼ 3.45). Direct current stripping voltammetry (DCSV) has been used for the determination of the drug under investigation. The effect of the different parameters e.g. initial potential, scan rate, …etc. has been tested. The detection limit has been determined for azo dye salpha drug and its related compounds. Relative standard deviation at the 1 × 10−5M level was 2.9%. The method was applied to the determination of the compounds in urine...

Adsorptive stripping voltammetric determination of antihypertensive agent: diltiazem ☆

Adsorptive stripping voltammetry was used to determine the antihypertensive agent diltiazem in phosphate buffer (pH 7.0). The adsorptive cathodic peak was observed at -1.72 V vs. Ag/AgCl. The peak response was characterized with respect to pH, preconcentration time, possible interferences, accumulation potential and supporting electrolytes. The obtained results were analyzed and the statistical parameters were calculated. The proposed method was applied to determine the mentioned drug in pharmaceutical formulation (capsule) and urine. The detection limit is 1x10(-8) M (4.5 ng ml(-1)) using 180 s preconcentration time, whereas the lower limit of detection is 6x10(-9) M (2.7 ng ml(-1)).

Adsorptive Cathodic Stripping Voltammetric Determination of Molybdenum in Synthetic Solutions and Environmental Samples

A sensitive and selective voltammetric methods has been developed for the determination of trace amounts of Mo(VI) ions. This method is based on controlled adsorptive preconcentration of molybdenum species on the hanging mercury drop electrode (HMDE) using mixtures of nitrate and phosphate as supporting electrolytes. The adsorptive stripping response was evaluated with respect to preconcentration time, potential and composition of supporting electrolyte. The method used is cathodic linear sweep stripping voltammetry (CLSSV). The detection limit found was 1610 78 M using 120 s. as accumulation time. The precision of the method is satisfactory with relative standard deviation of 1.4% with five replicates at 1610 76 M Mo(VI). The effect of various surface active substances (SAS) as well as different metal cations and anions in synthetic aqueous solutions has been investigated. Also this method has been applied for the determination of Mo(VI) in environmental samples; e.g., soil, natural water and indoor airborne particulate.

The polarographic behaviour of ketoprofen and assay of its capsules using spectrophotometric and voltammetric methods.

The quantitative determination of ketoprofen using spectrophotometric and voltammetric methods are described. The spectrophotometric procedure depends upon the reaction of ketoprofen with N-bromosuccinimide (NBS). The residual reagent is then determined by formation of violet colour with 2,2-diphenyl-l-picryl hydrazine (DPPH(2)). The consumed NBS would correspond to ketoprofen. Beers law is valid over the concentration range 5-80 mug/ml of the drug. Direct current (DC) polarography allows to study the reduction behaviour of ketoprofen at the dropping mercury electrode (DME) using different supporting electrolytes at different pH values. Direct current stripping voltammetry (DCSV) was used for the quantitative measurements of the drug. The calibration graph of peak current vs concentration was linear from 0.254 x 10(-2) to 0.254 mug/ml. In model solutions as little as 5.08 x 10(-4) ng/ml ketoprofen can be detected by DCSV. Both methods were applied successfully for the determination of ketoprofen either in pure or dosage forms.

Cathodic adsorptive stripping voltammetric determination of muscle relaxant: gallamine triethiodide (flaxedil)

A sensitive and simple voltammetric method of analysis is developed for the determination of trace amounts of gallamine triethiode in phosphate media. This method is based on controlled adsorptive preconcentration of the relaxant onto a Hanging Mercury Drop Electrode (HMDE) whereby mercurous iodide salt(s) are formed. The technique used is Cathodic Linear Sweep Stripping Voltammetry (CLSSV). The adsorptive response was evaluated with respect to preconcentration time and potential. As little as 3 x 10(-9) mol dm(-3) i.e. 2.7 ppb flaxedil (proconcentration time 300 seconds) can be determined successfully. The application of this method was tested in the determination of flaxedil in pharmaceutical preparation (ampoules).

Quantification of tiaprofenic acid using voltammetric and spectrophotometric techniques

Two methods for the determination of tiaprofenic acid (Surgam) are described. Direct current polarography and cyclic voltammetry were used to study the reduction behaviour of tiaprofenic acid, whereas direct current stripping voltammetry was applied to the quantitative measurement of the drug in dosage form and in biological media. The spectrophotometric method depends on the determination of the drug after extraction as an ion-association complex with Safranine-T in chloroform at pH 7.4.

Adsorptive stripping voltammetric determination of uranium with cephradine

Uranium adsorbed with cephradine is reduced on a hanging mercury drop electrode. This property was exploited in developing a highly sensitive stripping voltammetric procedure for the determination of uranium. A detection limit 2 × 10–9 mol l–1(0.5 µg l–1) of uranium ion is obtained with an 180 s accumulation time. Cyclic voltammetry was used to characterize the interfacial and redox behaviour. The effects of various parameters are discussed. Experimental conditions include the use of 5 × 10–6 mol l–1 cephradine in 0.05 mol l–1 sodium perchlorate (pH ≈ 6.5), an accumulation potential of 0.0 V versus SCE and a direct current stripping technique. The response is linear up to 5 × 10–6 mol l–1 uranium and the relative standard deviation at 1 × 10–7 mol l–1 UO2+ is 4.4%. The effect of other metal ions was investigated.