Reversed phase partition chromatography

Saturated lecithins and the three types of aldehydic cores obtained by reductive ozonolysis of unsaturated lecithins can be separated through reversed phase partition chromatography [168]. Fig. 147 shows photo-densitometric curves from thin-layer chromatograms of fission products derived from the lecithins of egg, bovine spinal cord, soya bean and wheat germ. 

This was the first and only procedure for several years for analysis of the four lecithin types. Only recently have appreciably more subtle methods been developed [14, 174] they are described on p. 392 and 404. 

This method can be employed for fractionating lipids according to compound classes (see p. 408 and 414) it has found greater application, however, for separating mixtures of vinylogous and homologous substances 

Certain saturated and unsaturated compounds migrate together in TLC on layers which have been rendered hydrophobic this is as found in other partition procedures such as liquid-liqtdd counter-current distribution and partition chromatography in columns or on impregnated paper. Thus, as seen from Fig. 148, methyl palmitate (C g, saturated) and methyl oleate (C g, monoolefine) appear together in one spot as do methyl myristate (Cj4, saturated) and methyl linoleate (Cjg, diolefine). Such critical pairs are likewise formed by the corresponding free acids or aldehydes and also by tripalmitin/triolein and trimyristin/trilinolein [78]. 

Most critical pairs may be separated through reversed phase partition chromatography by working at low temperature (see p. 94). Another way is to develop the unsaturated lipids through quantitative oxidation with a peroxidic solvent, which has no influence on the separation 

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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. 

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-... 

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). 

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]. 

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

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. 

Liquid adsorption chromatography Liquid reversed phase partition chromatography Adsorption and partition chromatography with supercritical fluid mobile phases... 

Urushigawa, Y., and Y. Yonezawa (1979), Chemicobiological Interactions in Biological Purification System VI. Relation between Biodegradation Rate Constants of Di-u alkyl Phthalate Esters and Their Retention Times in Reverse Phase Partition Chromatography, Chemosphere 5, 317-320. 

Testa C. 1970. Column reversed-phase partition chromatography for the isolation of some radionuclides from biological materials. Anal Chim Acta 50 447-455. 

It is a difficult task to isolate the higher actinides in the HLW, particularly to separate them from the lanthanides, because these elements all are present in solution as trivalent ions of similar size and therefore have very similar chemical properties. The separation methods utilize their slightly different complex forming abilities in techniques such as solvent extraction, ion exchange, and reversed phase partition chromatography. Three solvent extraction processes have been run on a larger experimental scale ... 

Reversed-phase partition chromatography is a special case of solvent extraction An extractant is attached to an immobile support, and an immiscible mobile phase flows past. Molecular species containing the analyte partition between the two phases. It is usually the organic phase that is attached to the support and the aqueous phase that flows (Hulet 1964 Bark et al. 1967). The standard solvent extraction processes are carried out on the column. The organic phase is distributed on the surface of small, equally sized particles that are placed in a glass tube, called a chromatographic column. 

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