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- Especiação de cobre e zinco em urina - importância dos metais em doenças neurodegenerativasPublication . Leal, Fernanda; Catarino, Rita I. L.; Pimenta, Adriana M.; Souto, Maria Renata S.; Pinheiro, Tatiana S.N.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.
- Cathodic voltammetric detection of diltiazem at a bismuth film electrode: application to human urine and pharmaceuticalsPublication . Catarino, Rita I. L.; Leal, M. Fernanda C.; Pimenta, Adriana M.; Souto, M. Renata S.; Lopes, Joana R. T.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).
- Ofloxacin determination in urine, serum and pharmaceuticals using an automatic flow potentiometric systemPublication . Pimenta, Adriana M.; Souto, M. Renata S.; Catarino, Rita I. L.; Leal, M. Fernanda C.; Lima, José L. F. CostaAn automatic system was developed to determine ofloxacin in biological fluids and pharmaceutical formulations. Drug detection was carried out by a potentiometric membrane sensor based on [bis(trifluoromethyl)phenyl]borate as molecular-recognition material. The tubular shaped detector system was solidly attached to the manifold, creating a high-throughput stable setup (50 samples per hour) appropriate for routine antibiotic assessment. Under the optimized flow conditions, the sensor displayed a mean detection limit of 1 × 10 -5 M, a linear response over the concentrations of 2 × 10 -5 to 5 × 10 -3 M (slope of 57.4 mV decade -1 ) and a wide working pH range (2.1-6.6). The procedure was successfully applied to ofloxacin analysis in pharmaceuticals (relative deviation lower than 6%) and biological fluids at levels usually found after drug administration of clinical doses (recoveries between 91 and 106%). No significant interference from common excipients found in commercial formulations and inorganic ions usually present in biological fluids was noticed.