Polyana Fernandes Pereira

Fast batch injection analysis system for on-site determination of ethanol in gasohol and fuel ethanol

A simple, accurate and fast (180 injections h(-1)) batch injection analysis (BIA) system with multiple-pulse amperometric detection has been developed for selective determination of ethanol in gasohol and fuel ethanol. A sample aliquot (100 μL) was directly injected onto a gold electrode immersed in 0.5 mol L(-1) NaOH solution (unique reagent). The proposed BIA method requires minimal sample manipulation and can be easily used for on-site analysis. The results obtained with the BIA method were compared to those obtained by gas-chromatography and similar results were obtained (at 95% of confidence level).

Two new electrochemical methods for fast and simultaneous determination of codeine and diclofenac.

In this paper, we present two new electrochemical methods for fast and simultaneous determination of codeine (CO) and diclofenac (DCF). The first one is based on batch injection analysis with amperometric detection (BIA-MPA) and the second one is based on capillary electrophoresis with capacitively coupled contactless conductivity detection (CE-C(4)D). The proposed BIA-MPA method is highly-precise (RSD of 1.1% and 0.9% for DCF and CO, respectively; n=10), fast (300 injections h(-1)) and has low detection limits (1.1 and 1.0 µmol L(-1) for DCF and CO, respectively). The proposed CE-C(4)D method allows the determination of CO and DFC in less than 1 min with high precision (RSD of 0.3% and 0.7% for DCF and CO, respectively; n=10) and low detection limits (11 and 21 µmol L(-1) for DCF and CO, respectively). Both proposed methods were applied to the determination of CO and DCF in pharmaceutical samples with similar results to those achieved by high-performance liquid chromatography (HPLC) at a 95% confidence level.

Determinação de nimesulida por análise por injeção em fluxo com detecção amperométrica de múltiplos pulsos

A simple and fast method for the determination of nimesulide (NI) using flow injection analysis with multiple-pulse amperometric (FIA-MPA) detection at a boron-doped diamond (BDD) electrode was developed. The method was based mainly on the application of a four-potential waveform, E1(det) = -0.8 V / 30 ms, E2(det) = 0.6 V / 30 ms, E3(det) = -0.4 V / 30 ms and E4(cleaning) = -0.45 V / 300 ms versus Ag/AgCl (3.0 mol L-1 KCl). NI was detected at three different electrode potentials, at which the nitro group undergoes different redox reactions. The proposed method was selective and sensitive (detection limit of 81.0 nmol L-1), and successfully applied for the determination of NI in pharmaceutical formulations, yielding similar results to those obtained by the reference method.

Determinação rápida e simultânea de sulfametoxazol e trimetoprima utilizando análise por injeção em batelada com detecção amperométrica e eletrodo de diamante dopado com boro

A fast, simple procedure for simultaneous determination of sulfamethoxazole (SMX) and trimethoprim (TMP) was performed using batch injection analysis with multiple pulse amperometric detection (BIA-MPA). The sample aliquot (150 µL) was directly injected onto the boron-doped diamond (BDD) electrode (wall-jet configuration) immersed in a BIA system. The analytical characteristics of the proposed method include high analytical frequency (up to 75 injections per hour), good stability (RSD < 2.9%; n = 10), low detection limits (0.227 and 0.173 mg L-1 for SMX and TMP, respectively) and minimal waste generation. The proposed method yielded similar results to those obtained by liquid chromatography at a 95% confidence level.

A high-throughput BIA-MPA method for the simultaneous determination of amiloride and furosemide

In this work, a simple and fast batch injection analysis system with multiple pulse amperometric detection (BIA-MPA) was developed for the simultaneous determination of amiloride (AMD) and furosemide (FMD). A sample plug (150 μL) was directly injected into the unmodified boron-doped diamond (BDD) electrode immersed in 0.1 mol L−1 borate buffer (pH = 10). Simple and fast sample pre-treatment steps were required (dissolution and dilution). The analytical characteristics of the proposed method include good stability (RSD < 1.1%; n = 20), low detection limits (0.13 and 0.94 mg L−1 for AMD and FMD, respectively), high throughput (72 injections per h) and minimal waste production (∼150 μL by analysis). The results obtained with the BIA-MPA method were compared to those obtained by HPLC; similar results were obtained (at a 95% confidence level).