RESUMO
A glassy carbon electrode was modified with magnetite and platinum nanoparticles stabilized with 3-n-propyl-4-picoline silsesquioxane chloride. This chemically-modified electrode is proposed for the first time for the individual or simultaneous electrochemical detection of nitrophenol isomers. Nanoparticles act as catalysts and also increase the surface area. The polymer stabilizes the particles and provides the electrochemical separation of isomers. Under optimized conditions, the reduction peak currents, obtained by differential-pulse voltammetry, of 2-, 3-, and 4-nitrophenol increased linearly with increases in their concentration in the range of 0.1-1.5µmolL-1. In individual analysis, the detection limits were 33.7nmolL-1, 45.3nmolL-1 and 48.2nmolL-1, respectively. Also, simultaneous analysis was possible for 2-, and 4-nitrophenol. In this case, the separation of the peak potentials was 0.138V and the detection limits were 69.6nmolL-1 and 58.0nmolL-1, respectively. These analytical figures of merit evidence the outstanding performance of the modified electrode, which was also successfully applied to the individual determination of isomers in environmental and biological samples. The magnetite and platinum nanoparticles modified glassy carbon electrode was able to detect nitrophenol isomers at the ppm level in rain water and human urine samples.
Assuntos
Técnicas Eletroquímicas/instrumentação , Monitoramento Ambiental/instrumentação , Nanopartículas de Magnetita/química , Nitrofenóis/urina , Platina/química , Adulto , Eletrodos , HumanosRESUMO
OBJECTIVE: To standardize a technique for ventilating rat fetuses with Congenital Diaphragmatic Hernia (CDH) using a volume-controlled ventilator. METHODS: Pregnant rats were divided into the following groups: a) control (C); b) exposed to nitrofen with CDH (CDH); and c) exposed to nitrofen without CDH (N-). Fetuses of the three groups were randomly divided into the subgroups ventilated (V) and non-ventilated (N-V). Fetuses were collected on day 21.5 of gestation, weighed and ventilated for 30 minutes using a volume-controlled ventilator. Then the lungs were collected for histological study. We evaluated: body weight (BW), total lung weight (TLW), left lung weight (LLW), ratios TLW / BW and LLW / BW, morphological histology of the airways and causes of failures of ventilation. RESULTS: BW, TLW, LLW, TLW / BW and LLW / BW were higher in C compared with N- (p <0.05) and CDH (p <0.05), but no differences were found between the subgroups V and N-V (p> 0.05). The morphology of the pulmonary airways showed hypoplasia in groups N- and CDH, with no difference between V and N-V (p <0.05). The C and N- groups could be successfully ventilated using a tidal volume of 75 ìl, but the failure of ventilation in the CDH group decreased only when ventilated with 50 ìl. CONCLUSION: Volume ventilation is possible in rats with CDH for a short period and does not alter fetal or lung morphology. .
OBJETIVO: padronizar uma técnica para ventilar fetos de rato com HDC usando um ventilador volume-controlado. MÉTODOS: ratas grávidas foram distribuídas em: a) Controle (C); e b) Expostos a Nitrofen com HDC e sem HDC (N-). Fetos dos três grupos foram divididos aleatoriamente em subgrupos ventilados (V) ou não ventilados (NV). Os fetos foram coletados no dia 21,5 da gestação, pesados e ventilados por 30 minutos usando um ventilador volume-controlado. A seguir os pulmões foram coletados para estudo histológico. Nós avaliamos: peso corporal (PC), peso pulmonar total (PPT), peso do pulmão esquerdo (PPE), razão PPT/PC e PPE/PC, histologia morfológica das vias aéreas e as causas das falhas da ventilação. RESULTADOS: PC, PPT, PPE, LLW, PPT/PC e PPE/PC foram maiores em C em relação a N- (p<0,05) e a HDC (p<0,05), mas não houve diferenças entre os subgrupos V e NV (p>0,05). A morfologia das vias aéreas pulmonares mostrou hipoplasia nos grupos N- e HDC, não havendo diferença entre V e NV (p<0,05). Os grupos C e N- puderam ser ventilados com sucesso usando o volume corrente de 75ìl, mas a falha de ventilação no grupo HDC só diminuiu quando ventilados com 50ìl. . CONCLUSÃO: a ventilação a volume de ratos com HDC por um curto período é possível e não altera a morfologia fetal ou pulmonar. .