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High Extraction Efficiency (high + extraction_efficiency)
Selected AbstractsSolvent extraction studies of Sm(III) from nitrate medium and separation factors of rare earth elements with mixtures of sec -octylphenoxyacetic acid and 1,10-phenthrolineJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 6 2010Shujuan Fan Abstract BACKGROUND: Liquid,liquid extraction is widely used for the separation of rare earths, among which synergistic extraction has attracted more and more attention. Numerous types of synergistic extraction systems have been applied to rare earths with high extraction efficiency and selectivities. In the present study, mixtures of sec -octylphenoxyacetic acid (CA12, H2A2) and 1,10-phenanthroline (phen, B) have been used for the extraction of rare earths from nitrate medium. The stoichiometry of samarium(III) extraction has been studied using the methods of slope analysis and constant molar ratio. The possibility of using synergistic extraction effects to separate rare earths has also been studied. RESULTS: Mixtures of CA12 and phen display synergistic effects in the extraction of rare earth elements giving maximum enhancement coefficients of 5.5 (La); 13.7 (Nd); 15.9 (Sm); 24.5 (Tb); 45.4 (Yb) and 12.3 (Y). Samarium(III) is extracted as SmHA4B3 with mixtures of CA12 and phen instead of SmHA4 when extracted with CA12 alone. The calculated logarithm of the equilibrium constant is 6.0 and the thermodynamic functions, ,H, ,G, and ,S, have been calculated as 4.3 kJ mol,1, , 33.7 kJ mol,1 and 129.7 J mol,1 K,1, respectively. CONCLUSION: Mixtures of CA12 and phen exhibit synergistic effects on rare earth elements. Graphical and numerical methods have been successfully used to determine their stoichiometries. The different synergistic effects may provide the possibility of separating yttrium from heavy lanthanoids at an appropriate ratio of CA12 and phen. Copyright © 2010 Society of Chemical Industry [source] Analysis of flavor and perfume using an internally cooled coated fiber deviceJOURNAL OF SEPARATION SCIENCE, JSS, Issue 7 2007Yong Chen Abstract A miniaturized internally cooled coated fiber device was applied for the analysis of flavors and fragrances from various matrices. Its integration with a CTC CombiPAL autosampler enabled high throughput for the analysis of analytes in complex matrices that required simultaneous heating of the matrices and cooling of the fiber coating to achieve high extraction efficiency. It was found that up to ten times increase of extraction efficiencies was observed when the device was used to extract flavor compounds in water, even when limited sample temperatures were used to preserve the integrity of target compounds. The extraction of the flavor compounds in water with the device was reproducible, with RSD not larger than 15%. The lower limits of the linear ranges were in the low ppb range, which was about one order of magnitude smaller than those obtained with the commercialized 100 ,m PDMS fibers. Exhaustive extraction of some perfume ingredients from a complex matrix (shampoo) was realized. All achieved recoveries were not less than 80%. The repeatability of the extraction of the perfume compounds from shampoo was better than 10%. The linear ranges were about 1,3000 ,g/g, and the LOD was about 0.2,1 ,g/g. The automated internally cooled coated fiber device was demonstrated to be a powerful sample preparation tool in flavor and fragrance analysis. [source] Application of water as a solvent in microwave-assisted extraction for analysis of PCBs and CBzs in fly ashJOURNAL OF SEPARATION SCIENCE, JSS, Issue 6 2005Yifei Sun Abstract Polychlorinated biphenyls (PCBs) and chlorobenzenes (CBzs) are two classes of dioxin precursors formed in municipal solid waste incinerators (MSWIs); they produce negative health effects similar to those of dioxins. Reducing the analytical time required for determining the concentrations of these compounds in MSWIs is important for quickly evaluating their importance and assessing associated health risks. In the present study, water is used as a safe and environmentally friendly solvent in microwave-assisted extraction (MAE) for PCB and CBz analyses. MAE is compared with traditional Soxhlet extraction (SE) to determine the extraction efficiencies. The evaluation of extraction efficiencies shows that MAE has a high extraction efficiency compared with that of SE when water content is lower than 60%. Furthermore, the extraction time and organic solvent consumption are reduced with MAE compared with SE. [source] Identification and quantitation of phenolic compounds in faecal matrix by capillary gas chromatography and nano-electrospray mass spectrometryRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 20 2006Ulrike Knust Very few relevant methods have been described for the detection and quantitation of phenolic compounds in faecal matrix. Extraction with conventional organic solvents such as chloroform/methanol (2:1, Folch reagent), methanol and ethanol (72%) showed high extraction efficiency for lipids and also gave good recovery of the major phenolic compounds present in the matrix. However, in comparison with a newly developed phosphate buffer method, the yield of minor phenolics was negligible when detected by these conventional methods. Conventional methods also lead to contamination of the ion source of the mass spectrometer and rapid deterioration of column performance mostly due to the high concentration of lipids. However, if the faecal matrix is initially extracted with phosphate buffer, and the extract acidified and re-extracted with diethyl ether, the range and yield of phenolic compounds are enhanced and the problem of lipid contamination is substantially alleviated. Following pilot studies and optimisation of the procedure, individual phenolic compounds (n,=,29) were identified by nano-electrospray ionisation mass spectrometry (nano-ESI-MS), nano-ESI-tandem mass spectrometry (MS/MS) and gas chromatography/mass spectrometry (GC/EI-MS) and quantitated (n,=,27) by GC/MS in subsets (n,=,5) of faecal samples, collected during the European Agency for Cancer Prevention calcium/fibre intervention study from four European countries (Italy, Germany, Spain and Denmark). A range of phenolic compounds (mainly acids) was detected, dominated by phenylacetic, benzoic, phenylpropionic and m -hydroxyphenylpropionic acids, representing on average 9.91 (93%), 8.25 (92%), 9.45 (95%) and 11.05 (98%) mM in the Italian, German, Spanish and Danish samples, respectively. The new method should enable large epidemiologic, case-control and intervention studies on the relevance of phenolic antioxidants in the aetiology of colorectal cancer to be conducted in the future. Copyright © 2006 John Wiley & Sons, Ltd. [source] | ||||||||||