RESUMO
In organic and inorganic synthesis and in analytical methods, an external conventional heat source is usually applied to carry out a chemical reaction at a high temperature, or an extraction procedure. In the last decades, the use of ultrasound as an alternative energy source has become an interesting field of research in these topics in the South Cone region (Argentina, Chile, Uruguay, Southern Brazil and Paraguay). For this reason, the present review, covering the period 2009 to mid-2021, is a compilation of ultrasound-assisted synthetic and analytical methodologies.
RESUMO
Natural Deep Eutectic Solvents (NADES) are highly important for Green Chemistry principles and can be used instead of harmful organic solvents. Indeed, nowadays smartphone-based analytical devices can replace some traditional laboratory equipment. In the present work, a smartphone based dual spectrophotometer and spectrofluorometer device was designed, 3D manufactured, and validated. A resolution of 0.241 ± 0.010 pixel.nm-1 and a stability comparable with commercial instruments were obtained. Using the proposed device it was possible, for the first time, to study the role of water in NADES (fructose:urea:water) preparation, by testing the influence of structural and dilution water. In this sense, it was observed that when water was added before NADES preparation (integrated into the superstructure of the solvent), fluorescence and absorbance intensities sharply decayed (up to 90% and 95%, respectively). In contrast, dilution water had minor effects on spectroscopic features of the eutectic system, which was expressed as 29% and 23% of diminution of signal intensities for both techniques. The obtained results suggest that the moment the water is added plays a significant role in NADES properties.
Assuntos
Smartphone , Água , Extratos Vegetais , Solventes , Análise EspectralRESUMO
This work presents a new, simple and inexpensive reverse liquid-liquid microextraction of doxycycline (DOC) from chicken fat. In this just 13min extraction methodology, acidulated water, as extraction solvent (400µL), was used. A monochannel flow injection system was designed for the spectrometric determination of the analyte (Ê=344nm). The extracted solution containing DOC was loaded into the injection valve of the continuous flow manifold. A lineal range between 100 and 700µgDOCkg-1 sample was obtained. The LOD and LOQ were 33µgkg-1 and 100µgkg-1 respectively. The relative standard deviation was 4.87% and the sample throughput for the entire process was 4.5h-1. As recovery values when the method was applied to real samples showed variability, the expanded uncertainties were calculated. Their values indicated that the new method is independent of the concentration of the analyte and the origin of the sample.