Reversed-phase partition

Urushigawa Y, Yonezawa Y. 1979. Chemico-biological interactions in biological purification systems VI. Relation between biodegradation rate constants of di-n-alkyl phthalate esters and their retention times in reverse phase partition chromatography. Chemosphere 5 317-320. 

Solvent System3 Adsorption Reversed Phase Partition Chiral Ref... 

Smith, E. (1967). Application of reverse phase partition chromatography to the analysis of testosterone propionate in oil injectables. J. Pharm. Sci., 56(5), 630-634. 

The structure of silica gel tends to change with time and this creates problems of irreproducibility in the separations. To remedy this situation and reduce the gel s polarity, the reactivity of silanol groups can be used to covalently bind organic molecules. Bonded stationary phases behave like liquids. However, the separation mechanism now depends on the partition coefficient instead of adsorption (Fig. 3.9). Bonded phases, whose polarity can be easily adjusted, constitute the basis of reversed phase partition chromatography, which is used in the majority of analyses by HPLC. 

Recently, reversed-phase partition chromatography has become the method of choice for both qualitative and quantitative analysis of carotenoids. The stationary phases commonly used are those with C,8-bonded chains (ODS) their performances are influenced by the extent of endcap-... 

In principle, h.p.Lc. arose from conventional liquid column chromatography, following the development of g.l.c. and realisation that it was a rapid and accurate analytical method. This led to a reappraisal of the liquid column chromatographic system, which in turn resulted in research developments in instrument design and in the manufacture of column-packing materials. These now have precise specifications to make them suitable for adsorption, normal and reversed phase partition, ion exchange, gel permeation, and more recently affinity chromatography. 

Environmental Arsenic Different species Reverse-phase partition 300 pg Beauchemin et al. (1989)... 

Chromatography of Bile Pigments In 1953 Cole and Lathe (C5) subjected protein-free filtrates of icteric serum to reverse phase partition chromatography. Using silicone-treated... 

B6. Billing, B. H., Quantitative determination of bile pigments in serum using reverse phase partition chromatography. Biochem. J. 56, Proc. xxx (1954). 

Fig. 6.5 shows excellent separations of four proteins in both moderate (Fig. 6.5a) and high EOF columns (Fig. 6.5b) using electrically driven flow, and compares the separation with that achieved using standard HPLC methodology (Fig. 6.5c). Since the separations were primarily governed by the nature of the mobile phase gradient, all three chromatograms are very similar. This comparison also demonstrates that the separation is achieved via reversed-phase partitioning rather than electrophoresis.

Non-polar and moderately polar solutes generally present the least difficulty, and these extracts are amenable to reversed phase partition chromatography followed by final purification of separated fractions by adsorption chromatography. Reversed phase chromatography is a practical first step because it is effective for a very wide range of compounds, and secondly because it has less tendency to be "fouled" by irreversible absorption of highly polar contaminants. 

Extraction chromatography (reversed phase partition chromatography) has been used in analytical and biochemistry to effect chemical separations. It is a method which combines the simplicity of ion exchange and the selectivity of solvent extraction. Ion exchange theory may be used to calculate the number of theoretical plates in the column and the enrichment coefficient. Extraction chromatography as a separation method has been recently reviewed by Cerrai (J) and Katykhin (7). 

This is based on the partitioning of a substance between two liquid phases, in this instance the stationary and mobile phases. Substances which are more soluble in the mobile phase will pass rapidly through the system while those which favour the stationary phase will be retarded (Fig. 31.2). In normal phase partition chromatography the stationary phase is a polar solvent, usually water, supported by a solid matrix (e.g. cellulose fibres in paper chromatography) and the mobile phase is an immiscible, non-polar organic solvent. For reversed-phase partition chromatography the stationary phase is... 

In addition to LH-20, a wide range of other lipophilic Sephadex derivatives has been prepared to improve the flexibility of the gel in organic solvents [219]. For example, hydroxypropylated G-50 was used to characterise a range of oligomeric polyethers [220] and a lipophilic derivative of G-15 was used for the analytical characterisation of pyr-ethrum extracts [221], A chiral derivative of LH-20 was prepared by reaction of the gel with 23,24-oxido-5/3-cholane [222]. The gel formed swelled in both polar and non-polar solvents and its application in both straight-phase and reversed-phase systems was discussed. A hydroxy-cyclohexyl derivative of LH-20, suitable for straight-phase and reverse-phase partition chromatography, has been prepared and evaluated in the separation of various steroids [223]. 

The quantitative analysis of the fat-soluble vitamins (A, E, D and K) and their esters by reversed-phase partition in water/alcohol solvents on Zipax columns has been reported [255]. The applicability of gas and high pressure liquid chromatography of vitamin A was discussed by Vecchi, Vesely and Oesterhelt [256] who concluded that HPLC was superior in this application. 

Alimarin, I. P., Bolshova, T. A. Separation and concentration of elements by reversed-phase partition-chromatography. Pure AppL Chem. 31, 493 (1972)... 

Unexpected pH dependencies were explained by (a) competition between negative analyte ions and OH ions for interaction with the electrical double layer and (b) a mixed retention mechanism in which reverse-phase partition or interaction with unreacted silanols from the stationary-phase base may play a significant role. 

There are a number of modes or mechanisms into which chromatography is divided. These include adsorption, normal-phase partition, reversed-phase partition, and ion exchange. Often, the term partition is deleted from the discussions of the differences and similarities of these modes. The word partition initially arose when supports had to be coated with a liquid phase (and the mobile phases saturated with them) to accomplish separations with these two modes. Today, bonded-phase versions of these liquid phases are available, making them easier to use with greater reproducibility. Perhaps it has been the use of these bonded supports that have enabled the name of the mode to be simplified. 

Before bonded phases became available, all normal-phase partition — and reversed-phase partition — separations were done on silica and other supports which were only coated with different polar and nonpolar phases or oils. Obviously, their use presented many problems, because it was absolutely necessary to keep both the mobile phase and the stationary phases saturated with these phases. The laboratory work of the analytical chemist was made infinitely simpler with the introduction of bonded phases, which this topic addresses. 

Mussini, E., and F. Marcucci Methylated sephadex as support in reversed phase partition chromatography. J. Chromatogr. [Amsterdam] 17, 574(1965). 

Partition chromatography is categorized as either GLC or liquid-liquid chromatography (LLC). LEG is further categorized as either normal phase or reversed phase. For normal-phase LLC a polar liquid is used as the stationary phase, and a relatively nonpolar solvent or solvent mixture is used as the mobile phase. In reversed-phase partition chromatography, the stationary phase is nonpolar, and the mobile phase is relatively polar. ... 

In normal-phase partition chromatography, the stationary phase is polar and the mobile phase nonpolar. In reversed-phase partition chromatography, the polarity of these phases is reversed. 

Typical thin-layer separations are performed on a glass plate that is coated with a thin and adherent layer of finely divided particles this layer constitutes the stationary phase. The particles are similar to those described in the discussion of adsorption, normal- and reversed-phase partition, ion-exchange, and size-exclusion column chromatography. Mobile phases are also similar to those employed in high-performance liquid chromatography. 

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