Separation factors, extraction organic substances

TABLE XV. Summary of Separation Factors for the Extraction of Organic Substances from Nonpolar Matrices via Use of Normal Aqueous Micellar Systems... 

Based upon the use of nonionic surfactant systems and their cloud point phase separation behavior, several simple, practical, and efficient extraction methods have been proposed for the separation, concentration, and/or purification of a variety of substances including metal ions, proteins, and organic substances (429-441. 443.444). The use of nonionic micelles in this regard was first described and pioneered by Watanabe and co-workers who applied the approach to the separation and enrichment of metal ions (as metal chelates) (429-435). That is, metal ions in solution were converted to sparingly water soluble metal chelates which were then solubilized by addition of nonionic surfactant micelles subsequent to separation by the cloud point technique. Table XVII summarizes data available in the literature demonstrating the potential of the method for the separation of metal ions. As can be seen, factors of up to forty have been reported for the concentration effect of the separated metals. 

Consider two substances, A and B, present in a solution. Initially, the concentration ratio is CJCb, after extraction, the concentration ratio in the organic phase will be CaFaIC Fb, where Fa and Fb are the corresponding fractions extracted. The ratio Fa/Fb (the factor by which the initial concentration ratio is changed by the separation) is a measure of the separation of the two substances. A corollary measure... 

The use of MS as a detector for TLC involves identification of substances in a mixture, as well their separation. A necessary condition in this approach is the purity of a sample within a spot on the chromatogram. A special problem is the large quantity of support and, sometimes, a binding material and mobile-phase residues. Some other factors that might potentially hinder TLC/MS are water, which is physically bound to the support, as well as, in some cases, the organic modifier of the support. A factor which complicates the detection process in TLC/MS may also be the presence of derivatives in a sample peak displayed on a chromatogram. That is why the analyzed sample should be as free of contamination with other additives as possible and the support matrix should be carefully removed before MS analysis. These indications refer, to a lesser degree, to other methods of detection that are performed after total extraction of sample molecules from a sample matrix. It is a widely known fact that most of the... 

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