The main purpose of this review is to report the development and potentialities of batch injection analysis (BIA) and call the attention of researchers about the power of this (until now) almost unexplored tool. The text focuses on the concepts and potentialities of BIA combined with other techniques for analytical purposes. The association of BIA with amperometry, potentiometry, voltammetry, calorimetry, fluorescence and spectrophotometry is presented and important aspects related with each technique are discussed. Some aspects comparing the similarities and differences between BIA, FIA and wall-jet are presented along the text.
A new composite material constituted by mu-{5,10,15,20-tetra(4-pyridyl)porphyrinato cobalt(iii)}-tetrakis-{chloro-bis-(2,2'-bipyridine)ruthenium(ii)} complex (or CoTRP) and cobalt oxide, exhibiting high stability and sensitivity for the quantification of hydrogen peroxide, was obtained by the electrochemical polymerization of the tetraruthenated cobalt porphyrin in alkaline medium. The optimized experimental conditions for the preparation of the modified glassy carbon electrodes and for analysis of H2O2 were carefully determined. Fast sequential analysis (120 determinations h(-1)) in a wide linear dynamic range (5.0 x 10(-7) mol L(-1) to 2.0 x 10(-3) mol L(-1)), with high sensitivity and low detection limit (2.0 x 10(-7) mol L(-1)), was achieved by using these electrodes and the batch injection analysis (BIA) technique. Such characteristics allied to a good stability were explored for the specific determination of hydrogen peroxide in six commercial cosmetics and pharmaceutical product samples, giving results in excellent agreement with those obtained by the spectrophotometric method.
Batch injection analysis (BIA) utilizing amperometric detection with glassy carbon electrodes modified with [Co(TPyP){Ru(bipy) 2 Cl} 4 ](TFMS) 5 ¥ H 2 O porphyrin films were explored for acetaminophen analysis in pharmaceutical formulations. BIA is an interesting alternative for application of electrodes modified with tetraruthenated porphyrins. This sensor exhibited sharp current response peaks, rapid washout and excellent reproducibility for BIAamperometric quantification of acetaminophen. Also, a wide linear working range (10 À4 to 10 À6 mol L À1 ) as well as high sensitivity and sampling frequency rate (detection limit 1.1 Â 10 À7 mol L À1 , sampling frequency 120 injections/ h) and a small volume of analysis (100 mL/injection) was achieved. Furthermore, the proposed method permits the direct quantification of acetaminophen in many pharmaceutical products, avoiding cumbersome processes as previous separations, solvent extraction or sample filtration. The new procedure was applied to the analysis of commercial pharmaceutical products and the results were in excellent agreement with the ones obtained by spectrophotometric method. Accordingly, this amperometric method showed to be very well suited for quality control analysis and other applications with similar requirements.
In this paper, the possibility of analyzing levodopa and carbidopa by differential pulse voltammetry (DPV) utilizing a glassy carbon electrode in 0.1 mol L À1 HClO 4 is reported. Cyclic voltammograms of levodopa show a redox couple with anodic and cathodic peak potentials at 0.58 V and 0.52 V (vs. Ag/AgCl), respectively. For carbidopa, there are two oxidation waves with maximum currents at 0.53 V and 1.02 V, without any cathodic counterpart at slow enough scan rate. Since in such conditions, the oxidation product of carbidopa does not undergo reduction, it is possible to analyze levodopa without interference. On the other hand, carbidopa can be determined between 0.85 V and 1.1 V in the presence of levodopa, coating the electrode with a Nafion film, which is selective for carbidopa. The developed methodology was applied to two different commercial samples of pharmaceutical products. The obtained data were compared with the results of the analysis by high performance liquid chromatography (HPLC) with UV detection, showing good correlation (relative errors changing between 0.4% and 3.5%) and absence of interference of the other components that accompanied the pharmaceuticals.
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