Liquid chromatography , natural

Reiner, E. Identification of bacteria by pyrolysis gas-liquid chromatography. Nature 1965, 206,1272-1274. 

Baxter, R.M. et al i960. Separation of hypnotic potentiating principles from the essential oil o Acorns calamus Linn, of Indian origin by gas-liquid chromatography Nature i%y. 466-467. 

Liquid chromatography is complementary to gas chromatography because samples that cannot be easily handled in the gas phase, such as nonvolatile compounds or thermally unstable ones, eg, many natural products, pharmaceuticals, and biomacromolecules, are separable by partitioning between a Hquid mobile phase and a stationary phase, often at ambient temperature. Developments in the technology of Ic have led to many separations, done by gc in the past, to be carried out by Hquid chromatography. 

Selectivity of chromatographic separation is known to be varied by changing both the nonstationary phase composition and adsorbent nature. It is shown that the less are the values of the reached selectivity coefficient the higher are the requirements to column effectiveness. In this connection the choice of stationai y phase with high and predicted selectivity coefficient for the compounds being separated is still remains a topical problem of high-performance liquid chromatography. 

The major chromatographic techniques can also be categorised according to tbe nature of the mobile phase used -vapour phase chromatography for when a gas is the mobile phase and liquid chromatography for when a liquid is the mobile phase. 

N. Masque, R. M. Marce and R Bonnll, Comparison of different sorbents for on-line solid-phase exti action of pesticides and phenolic compounds from natural water followed by liquid chromatography , J. Chromatogr. 793 257-263 (1998). 

Result of gas-liquid chromatography of natural gas. With some volatile mixtures, the sample can be as small as 10-6 L... 

As a result of its unique chemical and physical properties, silica gel is probably the most important single substance involved in liquid chromatography today. Without silica gel, it is doubtful whether HPLC could have evolved at all. Silica gel is an amorphous, highly porous, partially hydrated form of silica which is a substance made from the two most abundant elements in the earth s crust, silicon and oxygen. Silica, from which silica gel is manufactured, occurs naturally, either in conjunction with metal oxides in the form of silicates, such as clay or shale, or as free silica in the form of quartz, cristobalite or tridymite crystals. Quartz is sometimes found clear and colorless, but more often in an opaque form, frequently colored... 

Although silica gel was the catalyst that partly initiated the renaissance of liquid chromatography, it was quickly found that separations based solely on polarity had severe limitations. Furthermore, the labile nature of silica gel in aqueous environments coupled with its instability to extremes of pH provoked active research to develop... 

Mantoura, R.F.C. and Llewellyn, C.A., The rapid determination of algal chlorophyll and carotenoid pigments and their breakdown products in natural waters by reversed-phase high-performance liquid chromatography, A a/. Chim. Acta, 151, 297, 1983. 

Although saponification was found to be unnecessary for the separation and quantification of carotenoids from leafy vegetables by high performance liquid chromatography (HPLC) or open column chromatography (OCC), saponification is usually employed to clean the extract when subsequent purification steps are required such as for nuclear magnetic resonance (NMR) spectroscopy and production of standards from natural sources. 

Kamikura, M. and Nakazato, K., Natural yellow colours from gardenia fruit and colours found in commercial gardenia extract analysis of natural yellow colours by high performance liquid chromatography, J. Food Hygiene Soc. Japan, 26, 150,1984. 

Garcia-Falcon, M.S. and Simal-Gandara, J., Determination of food dyes in soft drinks containing natural pigments by liquid chromatography with minimal clean-up. Food Control, 16, 293, 2005. 

To determine the nature of the associated state, gel filtration high-performance liquid chromatography (HPLC) has been performed in a number of detergents with... 

Long, H., Zhu, Y. X., and Kissinger, P. T. (2003). Liquid chromatography with multi-channel electrochemical detection for the determination of natural phenolic compounds. Chin. J. Anal. Chem. 31, 631-634. 

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