Elution technique

Displacement chromatography is suitable for the separation of multicomponent bulk mixtures. For dilute multicomponent mixtures it allows a simultaneous separation and concentration. Thus, it permits the separation of compounds with extremely low separation fac tors without the excessive dilutiou that would be obtained in elution techniques. 

Temperature programming was introduced in the early days of GC and is now a commonly practiced elution technique. It follows that the temperature programmer is an essential accessory to all contemporary gas chromatographs and also to many liquid chromatographs. The technique is used for the same reasons as flow programming, that is, to accelerate the elution rate of the late peaks that would otherwise take an inordinately long time to elute. The distribution coefficient of a solute is exponentially related to the reciprocal of the absolute temperature, and as the retention volume is directly related to the distribution coefficient, temperature will govern the elution rate of the solute. 

THIN-LAYER CHROMATOGRAPHY — THE RECOVERY OF SEPARATED SURSTANCES RY ELUTION TECHNIQUES 8.9... 

The purpose of the experiment is to illustrate the elution technique for the recovery of pure substances after their separation by thin-layer chromatography. The experiment can be readily extended to include the quantitative determination of the recovered substances. 

An alternative elution technique is to transfer the powder (e.g. for bromophenol blue) to a glass column fitted with a glass-wool plug or glass sinter, and elute the dye with ethanol containing a little ammonia. The eluted solution, made up to a fixed volume in a small graduated flask, may be used for colorimetric/ spectrophotometric analysis of the recovered dye (see Chapter 17). A calibration curve must, of course, be constructed for each of the individual compounds. 

W E Court, Quantitative thin-layer chromatography using elution techniques. In Quantitative Paper and Thin-Layer Chromatography E J Shellard (Ed) Academic Press, New York, 1968, p 29... 

Figure 10, Red cell smears after the application of the add elution technique. A, artificial mixture of cells from newborn and adult. B, blood sample from a patient with Fanconts anemia (Hb-Fjto 14.6%).

Klelhauer, E. "Determination of Fetal Hemoglobin Elution Technique", In "The Detection of Hemoglobinopathies", p. 

In Chapter 7, approaches for visualization of zones in chromatograms are discussed, including use of nondestructive and destructive dyeing reagents, fluorescence quenching on layers with a fluorescent indicator, and densitometry. In Chapter 8, additional detection methods, such as those used for biologically active and radioactive zones, as well as the recovery of separated, detected zones by scraping and elution techniques are covered. 

The popularity of reversed-phase liquid chromatography (RPC) is easily explained by its unmatched simplicity, versatility and scope [15,22,50,52,71,149,288-290]. Neutral and ionic solutes can be separated simultaneously and the rapid equilibration of the stationary phase with changes in mobile phase composition allows gradient elution techniques to be used routinely. Secondary chemical equilibria, such as ion suppression, ion-pair formation, metal complexatlon, and micelle formation are easily exploited in RPC to optimize separation selectivity and to augment changes availaple from varying the mobile phase solvent composition. Retention in RPC, at least in the accepted ideal sense, occurs by non-specific hydrophobic interactions of the solute with the... 

Fusari et al. [66] described a qualitative thin-layer chromatography (TLQ elution technique, for the assay of primaquine and other pharmaceuticals. 

On-going studies to improve analytical methods for hexachloroethane and related compounds include the EPA "Master Analytical Scheme" being developed for organic compounds in water (Michael et al. 1988) and the research in supercritical fluid extraction (Lopez-Avila et al. 1991 Wieboldt et al. 1988). Research continues on improving extraction, concentration, and elution techniques, and detection devices (Eichelberger et al. 

These methods are based on elution techniques, followed by micro-analysis of the resultant eluate by adopting one or more of the undermentioned known methods, namely ... 

Although separations may be caused by elution, frontal and displacement analyses, yet the elution technique is the most common. This method makes use of a stream of carrier-gas flowing through the column. Precisely, a sample is injected into the carrier-gas as a plug of vapour that is swept into the head of the packed chromatographic column. Separation of components that comprise the sample results from a difference in the multiple forces by which the column materials tend to retain each of the components. 

Fluorescence detectors can also be used and while their sensitivity may be greater, they are less widely applicable owing to the smaller number of fluorescent compounds. Differential refractometers will detect changes in the refractive index of the solvent due to the presence of solutes and, while they are less sensitive than the other detectors and often cannot be used effectively with gradient elution techniques, they are capable of detecting the presence of any solute. 

Preservation, transport and storage of samples Investigation methods for soils, soil material and other materials Selection and pretreatment of samples Extraction and elution techniques (Table 4)... 

Baldwin RE. 1977. Adsorption-elution technique for concentration of hydrocarbon vapors. Arson Anal Newsl 1(6) 9-12. 

Gradient-elution techniques can be combined with elevated temperature operation or temperature programs [13-17], flow-rate programming [18,19], column switching, and two-dimensional (2D) operation [20-24] to get full advantage of separation selectivity and to separate complex samples in as short a time as possible. 

Vangala, R.R., Laib, R.J. Bolt, H.M. (1993) Evaluation of DNA damage by alkaline elution technique after inhalation exposure of rats and mice to 1,3-butadiene. Arch. Toxicol., 67,34-38... 

Barbin, A., Bereziat, J.C. Bartsch, H. (1983) Evaluation of DNA damage by the alkaline elution technique in liver, kidneys and lungs of rats and hamsters treated with V-nitrosodialkyl-amines. Carcinogenesis, 4, 541-545... 

Schwarz, M.. Hummel, J., Appel, K.E., Rickert, R. Kunz, W. (1979) DNA damage induced in vivo evaluated with a non-radioactive alkaline elution technique. Cancer Lett.. 6, 221-226... 

White, R.D., Sipes, I.G, Gandolfi, A.J. Bowden, GT. (1981) Characterization of the hepatic DNA damage caused by 1,2-dibromoethane using the alkaline elution technique. Carcinogenesis, 2, 839-844... 

Phenol did not induce DNA single-strand breaks in mouse lymphoma L5178Y cells. It was reported in abstracts that phenol induced DNA strand breaks in mouse lymphoma cells, as measured by the alkaline unwinding technique followed by elution through hydroxyapatite (Garberg Bolesfoldi, 1985), but that it did not induce strand breaks, as measured by the alkaline elution technique, in rat germ-cell DNA after either single or multiple dose treatments (Skare Schrotel, 1984). 

Resin capture can be faster and more efficient than classical methods of purification (e.g., chromatography). Chemoselective sequestration requires minimal amounts of solvent for separating reactants from solution-phase products. Gradient elution techniques, common in chromatographic separations, are avoided, saving time and solvent. Additionally, concurrent use... 

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