Conventional column chromatography

Classes of organic compounds analysed by this technique include non ionic surfactants, fatty acids, hydrocarbons (all types), organochlorine compounds, organosulphur and phosphorus compounds, substituted aromatic compounds, NTA, EDTA and insecticides and herbicides. Organometallic compounds studied include those of arsenic, lead, germanium, mercury and tin. 

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Despite the advances made in high-performance liquid chromatography in recent years, there are still occasionally applications in which conventional column chromatography is employed. These methods lack the sensitivity, resolution and automation of HPLC. They include the determination of urea herbicides in soil, polyaromatic hydrocarbons, carbohydrates, chloroaliphatic compounds and humic and fulvic acids in non-saline sediments. The technique has also been applied in sludge analysis, e.g. aliphatic hydrocarbons and carboxylic acids. 

Chromatographic methods seem to offer the only possibility to provide pure stoichiometric selenium sulfides as fractional crystallization and sublimation result in more or less complicated mixtures. Conventional column chromatography has turned out to be unsuccessful, but recently it has been shown that high-pressure liquid... 

Conventional column chromatography which predates more modem techniques such as high performance liquid chromatography is still of value in the analysis of waters. Applications of column chromatography are similar to those of high performance liquid chromatography. This technique is discussed in this chapter. 

Table 6.3 Conventional column chromatography of organic compounds in non saline waters...

High performance liquid chromatography (Chapter 4) which is displacing conventional column chromatography (Chapter 6) has found numerous applications in the analysis of organic compounds, also metal organic compounds of mercury, tin, arsenic, manganese copper and lead. It has fewer applications in the determinations of anions and cations. 

Preparative HPLC can be substituted by preparative TLC or by conventional column chromatography. 

These problems exclude conventional column chromatography from routine use for quality control however, application of minicolumns has offered an alternative to thin-layer chromatography in the cases of Tc-hexamethylpropylene amine oxime (HMPAO) and others, discussed in the respective monographs (Part 2). 

Centrifugal partition chromatography is an effective tool for the separation and purification of polar and unstable bioactive molecules. It expends a lot of time when these kinds of compounds are isolated by conventional column chromatography because of strong adsorption. The three major isoflavonoids in the root of Pueraria lobata have been isolated in a baseline state and with preparative scale. 

High-performance liquid chromatography (HPLC) is the newest of the chromatographic procedures to be used for the isolation and purification of fatty acids and lipids and already shows great potential. It has been developed mainly in the analytical mode for acids and esters, triacylglycerols and phospholipids. It is usually more efficient and quicker than conventional column chromatography. It has not been extensively employed in the preparative mode for fatty acids and their derivatives. 

Other major chromatographic methods, e.g., conventional column chromatography, thin-layer chromatography, and gas-liquid chromatography as well as conventional detection systems, e.g., fluorescence and the UV-VIS absorption of the retinoids themselves or of their colored products, have been used for many years. In these cases developments generally have focused either on special applications, on the simplification of procedures, on improvements in the preparation and stabilization of reagents, or on increased sensitivity. 

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