Molecularly imprinted polymer-based bulk optode for the determination of itopride hydrochloride in physiological fluids.

We report here for the first time on the use of Molecularly Imprinted Polymers as modifiers in bulk optodes, Miptode, for the determination of a pharmaceutical compound, itopride hydrochloride as an example in a concentration range of 1×10(-1)-1×10(-4)molL(-1). In comparison to the optode containing the ion exchanger only (Miptode 3), the optode containing the ion exchanger and the MIP particles (Miptode 2) showed improved selectivity over the most lipophilic species, Na(+) and K(+), by more than two orders of magnitude. For instance, the optical selectivity coefficients using Miptode 2, [Formula: see text] , were as follow: NH4(+)˂-6; Na(+)=-4.0, which were greatly enhanced in comparison with that obtained by Miptode 3. This work opens a new avenue for using miptodes for the determination of all the pharmaceutical preparations without the need for the development of new ionophores.

Extractive determination of ephedrine hydrochloride and bromhexine hydrochloride in pure solutions, pharmaceutical dosage form and urine samples.

Simple, rapid, sensitive, precise and accurate spectrophotometeric methods for the determination of ephedrine hydrochloride (E-HCl) and bromhexine hydrochloride (Br-HCl) in bulk samples, dosage form and in spiked urine samples were investigated. The methods are based on the formation of a yellow colored ion-associates due to the interaction between the examined drugs with picric acid (PA), chlorophyllin coppered trisodium salt (CLPH), alizarin red (AR) and ammonium reineckate (Rk) reagents. A buffer solution had been used and the extraction was carried out using organic solvent, the ion associates exhibit absorption maxima at 410, 410, 430 and 530 nm of (Br-HCl)with PA, CLPH, AR and Rk respectively; 410, 410, 435 and 530 of (E-HCl) with PA, CLPH, AR and Rk respectively. (E-HCl) and (Br-HCl) could be determined up to 13, 121, 120 and 160; 25, 200, 92 and 206 µg mL(-1), using PA, CLPH, AR and Rk respectively. The optimum reaction conditions for quantitative analysis were investigated. In addition, the molar absorptivity, Sandell sensitivity were determined for the investigated drug. The correlation coefficient was ≥0.995 (n=6) with a relative standard deviation (RSD) ≤1.15 for five selected concentrations of the reagents. Therefore the concentration of Br-HCl and E-HCl drugs in their pharmaceutical formulations and spiked urine samples had been determined successfully.

Validated polarographic methods for the determination of certain antibacterial drugs.

Two simple, precise, inexpensive and sensitive voltammetric methods for the determination of lomefloxacin (LFX), sparfloxacin hydrochloride (SFX), gatifloxacin (GFX), and moxifloxacin (MFX) were developed. The present methods were first used to explore the adsorption behavior of the four investigated antibacterial agents at a hanging mercury dropping electrode (HMDE), by a direct method and secondly by a modification via their complexation with PdCl(2). For the direct method, drugs were accumulated on HMDE, and a well-defined reduction peak was obtained in Britton-Robinson buffer of pH 7 for LFX and SFX, and pH 6 for GFX and MFX. The adsorptive stripping response was evaluated as a function of some variables such as the scan rate, pH, accumulation time and potential. For the modified method, the adsorptive behavior of Pd(II)-4-quinolone complexes at the HMDE developed a strippining voltammetry peak at a more negative potential than that of the free Pd(II) ions (-1.05 V). The limits of detection (LOD) were 2 x 10(-8) M, while the limits of quantification (LOQ) were 6 x 10(-8) M for the investigated drugs. The methods were applied to the determination of LFX, SFX, GFX, and MFX in biological samples and pharmaceutical preparations, and also compared with the official reference methods. Complete validation of the proposed methods was also done.

New conventional coated-wire ion-selective electrodes for flow-injection potentiometric determination of chlordiazepoxide.

New chlordiazepoxide hydrochloride (Ch-Cl) ion-selective electrodes (conventional type) based on ion associates, chlordiazepoxidium-phosphomolybdate (I) and chlordiazepoxidium-phosphotungstate (II), were prepared. The electrodes exhibited mean slopes of calibration graphs of 59.4 mV and 60.8 mV per decade of (Ch-Cl) concentration at 25 degrees C for electrodes (I) and (II), respectively. Both electrodes could be used within the concentration range 3.16 x 10(-6)-1 x 10(-2) M (Ch-Cl) within the pH range 2.0-4.5. The standard electrode potentials were determined at different temperatures and used to calculate the isothermal coefficients of the electrodes, which were 0.00139 and 0.00093 V degrees C(-1) for electrodes (I) and (II), respectively. The electrodes showed a very good selectivity for Ch-Cl with respect to the number of inorganic cations, amino acids and sugars. The electrodes were applied to the potentiometric determination of the chlordiazepoxide ion and its pharmaceutical preparation under batch and flow injection conditions. Also, chlordiazepoxide was determined by conductimetric titrations. Graphite, copper and silver coated wires were prepared and characterized as sensors for the drug under investigation.

Electrochemical adsorptive behavior of some fluoroquinolones at carbon paste electrode.

Cyclic voltammetry and differential pulse voltammetry were used to explore the adsorption behavior of three antibacterial agents at a carbon paste electrode. The drugs were accumulated on a carbon paste electrode, and a well-defined oxidation peak was obtained in acetate buffer (pH 5.0). The adsorptive stripping response was evaluated as a function of some variables such as the scan rate, pH and accumulation time. A simple, precise, inexpensive and sensitive voltammetric method has been developed for the determination of the cited drugs (Lomefloxacin (LFX), Sparfloxacin hydrochloride (SFX), and Gatifloxacin (GFX)). A linear calibration was obtained from 2 x 10(-7) M to 4 x 10(-5) M for LFX, 2 x 10(-7) M to 6 x 10(-5) M for SFX, and GFX. The limits of detection (LOD) were 4.2 x 10(-7), 7 x 10(-7) and 6.6 x 10(-7) M, while the limits of quantification (LOQ) were 1.4 x 10(-6), 2.3 x 10(-6) and 2.2 x 10(-6) M for LFX, SFX, and GFX, respectively. The R. S. D. of five measurements at the 1 x 10(-6) M level were 0.4, 0.5 and 0.3 for LFX, SFX and GFX, respectively. The method was applied to the determination of LFX, SFX and GFX in dilute urine samples and dosage forms, and compared with the HPLC method.

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.

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.