Navegando por Palavras-chave "Fase estacionária"

Agora exibindo 1 - 1 de 1
  • Imagem de Miniatura
    Item
    Acesso aberto (Open Access)
    Síntese de microesferas de sílica visando a aplicações analíticas
    (Universidade Federal de São Paulo, 2013-08-23) Silva, Camila Batista da [UNIFESP]; Assunção, Nilson Antonio de [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    The need to create miniaturized chromatographic beds has led to the search for stationary phases based on silica formed by micrometric particles. This is because chromatographic column with a reduced internal diameter, also known as nanocolumns, prepared with tiny particles, can act as excellent analytical tools, since various relevant chromatographic parameters (as mobile phase flow rate and running time) are benefited from the use of these devices. Accordingly, silica spheres with specific diameters and uniformity in size distribution can be synthesized by controlling the reaction conditions. In this work, silica microspheres were synthesized by the hydrolysis of an alkyl silicate (orthosilicate), catalyzed by ammonia in alcoholic solution. In the proposed study, there were variations in the reaction conditions, including changes in the concentration of the reagents, the reaction temperature, the reaction time and the size of the carbon chain alcohol and alkyl silicate. Characterization of microspheres was synthesized using scanning electron microscopy, which allowed the determination of particle size and its distribution, and adsorption/desorption of nitrogen measures (nitrogen physisorption), which promoted the determination of characteristics such as sphere’s surface area and pore’s diameter and volume. The results showed that controlling the synthesis conditions secured the production of silica spheres with diameters up to 2,84±0,09 µm, specific surface area of 280 m 2 /g, pore diameter of 74 Å and pore specific volume of 1,8 cm3 /g, which are characteristics considered suitable for the application as stationary phase in chromatographic systems miniaturized.