In this work, silica nanospheres were used as support for gold nanoparticles and applied for bisphenol A electrochemical detection. The development of new silica-supported materials has attracted increasing attention in the scientific world. One approach of interest is using silica nanospheres as support for gold nanoparticles. These materials have a variety of applications in several areas, such as electrochemical sensors. The obtained materials were characterized by solid-state UV-vis spectroscopy, electron microscopy, X-ray diffraction, and electrochemical techniques. The electrode modified with AuSiO₂700/CHI/Pt was applied as an electrochemical sensor for BPA, presenting an oxidation potential of 0.842 V and a higher peak current among the tested materials. The AuSiO₂700/CHI/Pt electrode showed a logarithmic response for the detection of BPA in the range of 1-1000 nmol L^-1, with a calculated detection limit of 7.75 nmol L^-1 and a quantification limit of 25.8 nmol L^-1. Thus, the electrode AuSiO₂700/CHI/Pt was presented as a promising alternative to an electrochemical sensor in the detection of BPA.

Glycerol, a by-product from biodiesel production can react with di-carboxylic organic acids, resulting in polyesters, and can be used in the composition of urea/formaldehyde or phenol/formaldehyde resins to improve the qualities of adhesion and moisture resistance of them. In this work, six kinds of resins derived from glycerol, named as GAA (glycerol/adipic acid), GAAU (glycerol/adipic acid/urea), GAF (glycerol/phtalic acid), GU (glycerol/urea), GUF (glycerol/urea/formaldehyde) and GF (glycerol/formaldehyde), were synthesized. The resins derived from carboxylic acids had better thermal stability (up to 350 ºC) than those derived from formaldehyde (up to 200 ºC). The average molecular weights of the resins were determined by matrix assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) and gel-permeation chromatography (GPC), and are in the range of 1800-2800 Da, being oligomers, and the polydispersity indexes are in the range of 1.3 to 1.8. The ¹H and 13C nuclear magnetic resonance (NMR) techniques were used to identify the structure of the resins.