O eletrodo compósito grafite-poliuretana foi avaliado na determinação de tetraciclina (TC) em amostras de água natural. Utilizando voltametria de pulso diferencial (DPV), uma resposta linear foi observada no intervalo de 4,00-40,0 µmol L-1 com limite de detecção de 2,80 µmol L-1 , sem necessidade de renovação da superfície entre medidas sucessivas. Durante determinação de tetraciclina em amostras de água, foram obtidas recuperações entre 92,6 e 100%. Os resultados para determinação de TC em amostras de água após a etapa de pré-concentração concordam com valor adicionado em um nível de confiança de 95% de acordo com o teste t-student. A bare graphite-polyurethane composite was evaluated in the tetracycline (TC) determination in natural water samples. Using differential pulse voltammetry (DPV), a linear response was observed in the range of 4.00-40.0 µmol L-1 with limit of detection of 2.80 µmol L-1 , without the need of surface renewing between successive runs. During the tetracycline determination in water samples, recoveries between 92.6 and 100% were found. The results for TC determination in water samples after a pre-concentration stage agreed with spiked value at a 95% confidence level according to student t-test.
Graphite powder was mixed to polyurethane, silicon rubber and Araldite® (epoxy) in order to prepare composite materials to be used in the preparation of electrodes. Results showed that voltammetric response could be obtained when at least 50% of graphite (w.w-1) is present in the material. SEM and thermogravimetry were also used in the characterization of the composites
A bare graphite-polyurethane composite was evaluated as an amperometric detector in the flow injection determination of atenolol in pharmaceutical formulations. Using a flow injection analysis (FIA) procedure, a linear analytical curve was observed in the 0.2-3.0 mmol L À1 range with a minimum detectable net concentration limit of detection (LOD ¼ 18.1 mmol L À1 and 90 determinations h À1 . Interferences from propranolol and furosemide were observed but not from the other components of the tablet. Thus, it was possible to determine atenolol in tablets without interference and with results that agreed with high performance liquid chromatography (HPLC) procedure with a 95% confidence level in a fast and accurate procedure.
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