Maria S.M. Quintino

Bia-amperometric quantification of salbutamol in pharmaceutical products

This paper presents a simple, rapid and reproducible method of analysis of salbutamol in pharmaceutical products, utilizing batch injection analysis (BIA) associated with amperometric detection. A study of salbutamol oxidation demonstrated a strong dependence between electrode fouling and pH. All determinations were done utilizing a glassy carbon electrode in presence of 3.0moll(-1) NaOH. A large linear dynamic range from 8x10(-7) to 2x10(-4)moll(-1) was obtained by using an injected volume of 100mul with a detection limit of 2.5x10(-7)moll(-1). R.S.D. of 0.92% for 50 successive injections of 4x10(-6)moll(-1) of salbutamol and a sample throughput of 60 samples per hour were achieved. The method was applied for salbutamol quantification in syrups.

Amperometric quantification of sodium metabisulfite in pharmaceutical formulations utilizing tetraruthenated porphyrin film modified electrodes and batch injection analysis

The performance of a glassy carbon electrode modified with a porphyrin film formed by the [Co(TPyP){Ru(bipy)(2)Cl}(4)](TFMS)(5).H(2)O complex for the analysis of sodium metabisulfite in pharmaceuticals is described. The sensor can be rapidly and easily prepared by drop-casting of a microliter volume of a diluted methanolic solution of the complex onto the electrode surface. The modified electrode with a supramolecular cobalt porphyrin film led to more favorable responses than the bare electrode. This can be ascribed to the much faster electron transfer processes to the analyte mediated by the tetraruthenated porphyrin and to the protection of the electrode against fouling. The association of the amperometric sensor with the batch injection analysis technique led to results that combine good repeatability of the current responses (relative standard deviation of 0.94% for 30 measurements), wide linear dynamic range (2.5x10(-7)molL(-1) to 5.0x10(-4)molL(-1)), high sensitivity and low limits of detection (8.1x10(-8)molL(-1)) and quantification (2.7x10(-7)molL(-1)). The system was successfully applied to sodium metabisulfite quantification in commercial samples of injection formulations of sodium (or potassium) diclofenac. The results compared well with those obtained by the polarographic method.

Amperometric determination of acetylsalicylic acid in drugs by batch injection analysis at a copper electrode in alkaline solutions.

This paper describes the determination of acetylsalicylic acid (ASA) as salicylate (SA) in pharmaceutical formulations by using amperometric detection with copper electrodes in 0.10 mol l(-1) NaOH solution. Batch injection analysis (BIA) was explored for this application. The system exhibited sharp current response peaks, rapid washout and excellent repeatability. A large linear dynamic range from 1 to 1000 mumol l(-1) was obtained by using an injected volume of 100 mul, with a detection limit of 0.48 mumol l(-1). R.S.D. of 0.37% for 30 repetitive (1x10(-4) mol l(-1)) injections and sampling frequency of 60 h(-1) were achieved. The results obtained using this system for ASA determination in seven different drug samples compared well with those found by spectrophotometry (Trinder test).

New hydrazine sensors based on electropolymerized meso-tetra(4-sulphonatephenyl)porphyrinate manganese(III)/silver nanomaterial.

A new electrocatalytic active porphyrin nanocomposite material was obtained by electropolymerization of meso-tetra(4-sulphonatephenyl)porphyrinate manganese(III) complex (MnTPPS) in alkaline solutions containing sub-micromolar concentrations of silver chloride. The modified glassy carbon electrodes efficiently oxidize hydrazine at 10mV versus Ag/AgCl, dramatically decreasing the overpotential of conventional carbon electrodes. The analytical characteristics of this amperometric sensor coupled with batch injection analysis (BIA) technique were explored. Wide linear dynamic range (2.5x10(-7) to 2.5x10(-4)molL(-1)), good repeatability (R.S.D.=0.84%, n=30) and low detection (3.1x10(-8)molL(-1)) and quantification (1.0x10(-7)molL(-1)) limits, as well as very fast sampling frequency (60 determinations per hour) were achieved.