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In this work, we report a simple and novel strategy for simultaneous analysis using flow injection analysis with multiple pulse amperometric (FIA-MPA) detection. The proposed strategy was successfully used for simultaneous determination of paracetamol and caffeine (model analytes) in pharmaceutical formulations. A sequence of potential pulses (waveform) was selected in such a way that PA is selectively oxidized at E 1 (+ 1.20 V/50 ms) and both compounds (PA + CA) are simultaneously oxidized at E 2 (+ 1.55 V/50 ms); hence, current subtraction (using a correction factor) can be used for the selective determination of CA. The proposed FIA method is simple, cheap, fast (140 injections h À1), and present selectivity for the determination of both compounds in pharmaceutical samples, with results similar to those obtained by HPLC at a 95 % confidence level.

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Este trabalho descreve a construção e caracterização de uma célula eletroquímica microfluídica com a inserção dos três eletrodos (trabalho, pseudo-referência e auxiliar) em microcanais com espessuras menores que 20 µm. Os microcanais foram construídos entre duas bases de policarbonato com o uso de uma ou mais máscaras de toner sobrepostas como espaçador. Esta estratégia permite a construção de microcélulas com um volume interno sobre o eletrodo de trabalho entre 0,6 a 2,4 µL. Três diferentes materiais foram otimizados como eletrodos nas microcélulas: filmes de ouro ou compósito de grafite como eletrodo de trabalho, compósito de prata como pseudo-referência e compósito de grafite como eletrodo auxiliar. O desempenho das células microfluídicas foi avaliado usando as técnicas de voltametria cíclica, redissolução potenciométrica a corrente constante e voltametria de redissolução anódica por onda quadrada empregando ferrocianeto e alguns metais pesados (Cu This work describes the construction and characterization of an electrochemical flow-through microcell with the three electrodes (working, pseudo-reference, and auxiliary) inserted in microchannels with thickness smaller than 20 µm. These microchannels were constructed between two stacked polycarbonate slides using one or more overlapped toner masks as spacer. This strategy allows the construction of microcells with a variable internal volume on the working electrode (0.6 to 2.4 µL). Three different materials were optimized as electrodes: gold film or graphiteepoxy composite as working electrode, silver-epoxy composite as pseudo-reference electrode and, graphite-epoxy composite as auxiliary electrode. The performance of the microfluidic cell was characterized by cyclic voltammetry, potentiometric stripping analysis at constant current, and square wave anodic stripping voltammetry using ferrocyanide and heavy metals (Cu

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