نتایج جستجو برای: separation and preconcentration
تعداد نتایج: 16843802 فیلتر نتایج به سال:
We present a comprehensive review and comparison of the methodologies for increasing sensitivity and resolution of capillary electrophoresis (CE) using online transient isotachophoresis (tITP). We categorize the diverse set of coupled tITP and CE (tITP-CE) methods based on their fundamental principles for disrupting isotachophoretic preconcentration and triggering electrophoretic separation. Ba...
in seawater. We present a new protocol for sample preparation and determination of REY concentrations in bivalve shells, that includes sample treatment with NaOCl followed by REY separation and preconcentration. The data obtained was further used to calculate REY partition coefficients between shells of M. edulis and ambient seawater, and acquired results were then used in the investigation of ...
Spectrometric techniques for the analysis of trace cadmium have developed rapidly due to the increasing need for accurate measurements at extremely low levels of this element in diverse matrices. This review covers separation and preconcentration procedures, such as electrochemical deposition, precipitation, coprecipitation, solid phase extraction, liquid-liquid extraction (LLE) and cloud point...
A new micell-mediated phase separation method for preconcentration of ultra-trace quantities of cadmium as a prior step to its determination by flame atomic absorption spectrometry has been developed. The method is based on the cloud point extraction (CPE) of cadmium in iodide media with Triton X-114 in the absence of any chelating agent. The optimal extraction and reaction conditions (e.g., ac...
in this thesis, a better reaction conditions for the synthesis of spirobarbiturates catalyzed by task-specific ionic liquid (2-hydroxy-n-(2-hydroxyethyl)-n,n-dimethylethanaminium formate), calcium hypochlorite ca(ocl)2 or n-bromosuccinimide (nbs) in the presence of water at room temperature by ultrasonic technique is provided. the design and synthesis of spirocycles is a challenging task becaus...
The performance and optimization of an anion exchanger phase (SAX) in line with a hydrophobic phase (C18) was studied for the preconcentration of selenite [Se(iv)], selenate [Se(vi)], dimethylselenide (DMSe), dimethyldiselenide (DMDSe), diethylselenide (DESe) and diethyldiselenide (DEDSe), using a GC-MS system to characterize the different selenium species. Optimum separation and preconcentrati...
The increasing use of automobile catalysts leads to the emission of the platinum-group elements (PGE), mainly platinum, but also rhodium and palladium into the environment. In environmental samples, the low concentration of platinum together with the high concentration of interfering matrix components often requires a preconcentration/enrichment step combined with a matrix-separation. The metho...
It is very important to investigate antimony geochemical behavior in order to identify its source, or reveal contamination processes, since antimony and its compounds are considered to be pollutants of high priority by the Environmental Protection Agency of the United States (USEPA). However, the concentration of antimony in most geological samples is very low, and its stable isotope mass diffe...
Micellar electrokinetic chromatography (MEKC) using a cationic surfactant as a pseudostationary phase was examined to separate anionic metal cyclohexane-1,2-diaminetetraacetic acid (CDTA) complexes. Cetyltrimethylammonium chloride (CTAC) was employed as the cationic surfactant micelle, its addition leading to EOF reversal. Cu(II), Co(II), Zn(II), Mn(II) and Pb(II) were used as test analytes, an...
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