Neste trabalho foi desenvolvida uma nova metodologia de voltametria catódica de onda quadrada com elétrodo de filme de bismuto (BiFE) para a determinação de um anti-hipertensivo e vasodilatador coronário - o diltiazem. O filme de bismuto foi depositado ex situ na superfície de um elétrodo de carbono vítreo durante 90 s a um potencial de -1,4 V vs. Ag/AgCl, usando uma solução de tampão acetato (pH 4,5; 0,10 mol L-1) contendo 5 ou 30 mg L-1 de Bi. O sinal analítico do diltiazem foi obtido numa solução de tampão fostato (pH 7,4; 0,25 mol L-1) onde se verificou que a redução ocorria a -1,5 V vs. Ag/AgCl. A metodologia proposta foi aplicada à quantificação de diltiazem em formulações farmacêuticas (faixa linear de resposta compreendida entre 90 e 900 µg L-1) e em amostras de urina (faixa linear de resposta compreendida entre 45 e 270 µg L-1, e limite de deteção de 12 µg L-1).

In this work it was developed a novel application of bismuth film electrodes (BiFEs) for the determination of the antihypertensive and coronary vasodilator diltiazem by square wave cathodic voltammetry. The bismuth film was deposited ex situ on a glassy carbon electrode for 90 s at -1.4 V vs. Ag/AgCl, from an acetate buffer (pH 4.5; 0.10 mol L-1) containing 5 or 30 mg L-1 Bi. Diltiazem analytical signal was obtained in phosphate buffer (pH 7.4; 0.25 mol L-1) where reduction takes place at -1.5 V vs. Ag/AgCl. The proposed methodology was applied to the quantification of diltiazem in pharmaceutical samples (dynamic linear range comprised between 90 and 900 µg L-1) and in human urine (dynamic linear range comprised between 45 and 270 µg L-1, and detection limit of 12 µg L-1).

Metals such as copper and zinc are essential for the development and maintenance of numerous enzymatic activities, mitochondrial functions, neurotransmission, and also for memorization and learning. However, disruption in their homeostasis can cause neurodegenerative disorders such as the Alzheimer and Parkinson diseases. In this work, the speciation of copper and zinc in urine samples was carried out. To this end, free and total metal concentrations were determined by square wave anodic stripping voltammetry using a glassy carbon electrode coated with bismuth film. The digestion of the samples was performed in a microwave with the addition of oxidant reagents.