Search results for "fluid"
showing 10 items of 5513 documents
Role of Phase Behavior and Atomization in the Supercritical Antisolvent Precipitation
2003
An experimental study on supercritical antisolvent (SAS) precipitation has been performed to gain insight into the role of phase behavior and atomization in controlling morphology and dimension of precipitates. The mixture yttrium acetate/dimethyl sulfoxide has been used as the main model system and supercritical CO 2 has been used as the antisolvent. Two SAS apparatuses (laboratory and pilot scale) with two injector arrangements and operating with various injector diameters in the range 60-500 μm have been used. The results showed that operating above the mixture critical point (MCP) of the ternary mixture yttrium acetate/dimethyl sulfoxide/ carbon dioxide, sub-micrometric particles are ge…
Molecularly imprinted polymer-based device for field collection of oral fluid samples for cocaine identification.
2020
In this paper, a low-cost, rapid, easy, and potentially portable tool for the identification of cocaine and its semi-quantitative determination in oral fluid has been proposed. A field collection device has been designed, based on a cotton pad with an indicator and a molecularly imprinted polymer (MIP) sorbent, to selective retain cocaine from oral fluid components. After sample collection, cocaine is transferred by using phosphate buffer to the MIP and then eluted with 2-propanol. The obtained extract is analysed by ion mobility spectrometry (IMS), providing a cut-off value of 20 µg L-1 that identifies 100 % true-positive and 95 % true-negative samples. The MIP-IMS procedure has been valid…
High-pressure solubility data of system ethanol (1)+catechin (2)+CO2 (3)
2001
Abstract Supercritical fluid extraction posses several advantages over traditional liquid–solvent-based extraction methods including improved selectivity, expeditiousness, automation and environmental safety. Fluid phase equilibrium data is essential for study the viability of supercritical extraction and the design of the extraction columns often used for this type of separations. During the past few years it has been demonstrated that phenolic compounds, such catechins and procyanidins from seeds, contribute to both the flavour properties and the pharmacological effects of wine. The extraction of catechin using supercritical CO2 is not possible, it only extracts traces of product, probabl…
High-pressure solubility data of the system resveratrol (3)+ethanol (2)+CO2 (1)
2001
Abstract Supercritical fluid extraction possesses several advantages over traditional liquid-solvent-based extraction methods, including improved selectivity, expeditiousness, automation and environmental safety. Fluid-phase equilibrium data are essential for studying the viability of supercritical extraction and the design of the extraction columns often used for this type of separation. Resveratrol has been correlated with serum lipid reduction and inhibition of platelet aggregation, and its cancer chemopreventive activity has recently been reported. The extraction of resveratrol using supercritical CO 2 is not possible; it only extracts traces of product, probably due to its polar nature…
Experimental and fluid dynamic study of continuous supercritical water gasification of glucose
2016
Abstract The supercritical water gasification (SCWG) of glucose as a model compound for H 2 production is studied in term of process development at 25 MPa and 650 °C. Gasification has been investigated using a laboratory scale continuous plant comprising a continuous down flow reactor with a volume of 200 cm 3 , a heat recovery section and pre-heat of the biomass to simulate more closely an industrial design. Feed streams (pure water and glucose solution) are introduced at the top of the vessel and products are extracted from the bottom. The reactor is equipped with various inlet points that allow to modify the inlet position of reacting streams in order to study the effect of stream mixing…
Densities, Viscosities, and Refractive Indices of Some Binary Liquid Systems of Methanol + Isomers of Hexanol at 298.15 K
1996
Viscosities, densities, and refractive indices of eight binary liquid systems containing ethanol + some isomers of hexanol have been determined at 298.15 K. The excess property values were fitted to the Redlich-Kister equation to estimate the binary coefficients and the standard deviations.
Sample preparation methods for the determination of pesticides in foods using CE-UV/MS.
2010
Much progress has been made in pesticide analysis over the past decade, during this time hyphenated techniques involving highly efficient separation with sensitive detection have become the techniques of choice. Among these, methods based on separation with mass spectrometric detection have resulted in greater likelihood of identification and are acknowledged to be extremely useful and authoritative methods for the determination of pesticide residues but the inherent advantages of the use of CE as a separation technique are well-known and can be summarized as high separation efficiency, low analysis time, high resolution power, and low consumption of samples and reagents. Although UV is the…
Study of kinetics of the d-pinitol extraction from carob pods using supercritical CO2
2014
Abstract There is a growing interest in the use of d -pinitol ( d -3-O-methyl-chiro-inositol) as a food supplement, thus the use of green and efficient process, such as the supercritical fluid extraction (SFE), to isolate d -pinitol from vegetable raw materials is also an interesting area of research and development. The objective of this work was to study the influence of operating conditions on the SFE of d -pinitol from carob pods. The crucial parameters in SFE, like temperature, pressure, CO 2 flow rate and duration of the process, have been studied. Finally, Naik and Barton models have successfully tested in order to fit the experimental extraction curves.
Pressurized liquid extraction of organic contaminants in environmental and food samples
2015
Pressurized liquid extraction (PLE) is an automated technique that uses elevated temperature and pressure to achieve exhaustive extraction from solid matrices, so reducing solvent consumption and enhancing sample throughput when compared with traditional procedures. Hence, it can be considered an environment-friendly technique, generating small volumes of waste and reducing costs and time. This review focuses on application of this green technique to the analysis of organic contaminants in food and environmental matrices for monitoring purposes. We examine fundamentals and key aspects of the development of a PLE method, including pressurized hot-water extraction, together with some relevant…
Determination of pesticides and their degradation products in soil: critical review and comparison of methods
2004
18 páginas, 5 figuras, 5 tablas.