Column chromatography, application

Cert, A. and Moreda, W. (1998) New method of stationary phase preparation for silver ion column chromatography application to the isolation of steroidal hydrocarbons in vegetable oils. J. Chromatogr., 823, 291-297. 

Although the OTHdC has several unique applications in polymer analysis, this technique has several limitations. First, it requires the instrumentation of capillary HPLC, especially the injector and detector, which is not as popular as packed column chromatography at this time. Second, as discussed previously, the separation range of a uniform capillary column is rather narrow. Third, it is difficult to couple capillary columns with different sizes together as SEC columns. 

Regarding the color, we only see a need for colorless ionic liquids in very specific applications (see above). One easy treatment that often reduces coloration quite impressively, especially of imidazolium ionic liquids, is purification by column chromatography/filtration over silica 60. For this purification method, the ionic liquid is dissolved in a volatile solvent such as CFF2C12. Usually, most of the colored impurities stick to the silica, while the ionic liquid is eluted with the solvent. By repetition of the process several times, a seriously colored ionic liquid can be converted into an almost completely colorless material. 

High performance liquid chromatography (HPLC) has been by far the most important method for separating chlorophylls. Open column chromatography and thin layer chromatography are still used for clean-up procedures to isolate and separate carotenoids and other lipids from chlorophylls and for preparative applications, but both are losing importance for analytical purposes due to their low resolution and have been replaced by more effective techniques like solid phase, supercritical fluid extraction and counter current chromatography. The whole analysis should be as brief as possible, since each additional step is a potential source of epimers and allomers. 

Compared with liquid column chromatography, in PLC there is a certain limitation with respect to the composition of the mobile phase in the case of reversed-phase chromatography. In planar chromatography the flow of the mobile phase is normally induced by capillary forces. A prerequisite for this mechanism is that the surface of the stationary phase be wetted by the mobile phase. This, however, results in a Umitation in the maximum possible amount of water applicable in the mobile phase, is dependent on the hydrophobic character of the stationary RP phase. To... 

In order to reduce the time-consuming open-column chromatographic processes, conventional methods of hydrocarbon-group-type separation have been replaced by MPLC and HPLC. Flash column chromatography is a technique less commonly applied than open-column version, but several applications have been described [2,24—27]. The common technique version is to use a silica-gel-filled column for example, 230 to 400 mesh 20 X 1 cm column size with a back pressure of 1.5 X 10 Pa of an ambient gas such as nitrogen. Solvents are similar to the ones apphed in the case of open-column chromatography fractionations. 

Dry column chromatography [528] provides several improvements over traditional column chromatography, such as better resolution and high speed. Another important characteristic is the near-quantitative applicability of TLC results in dry column analysis. Knowledge of the TLC characteristics of a sample is useful before column chromatography is employed. Careful control of the moisture content of the adsorbent is crucial to the dry column as well as other types of chromatography. 

Applications Open-column chromatography was used for polymer/additive analysis mainly in the 1950-1970 period (cf. Vimalasiri et al. [160]). Examples are the application of CC to styrene-butadiene copoly-mer/(additives, low-MW compounds) [530] and rubbers accelerators, antioxidants) [531]. Column chromatography of nine plasticisers in PVC with various elution solvents has been reported [44], as well as the separation of CHCI3 solvent extracts of PE/(BHT, Santonox R) on an alumina column [532]. Similarly, Santonox R and Ionol CP were easily separated using benzene and Topanol CA and dilaurylthiodipropionate using cyclohexane ethyl acetate (9 1 v/v) [533]. CC on neutral alumina has been used for the separation of antioxidants, accelerators and plasticisers in rubber extracts [534]. Column chromatography of polymer additives has been reviewed [160,375,376]. 

Samuel, C., Davis, J.M. (2002). Statistical-overlap theory of column switching in gas chromatography application to flavor and fragrance compounds. Anal. Chem. 74, 2293. 

Bordajandi, L.R., Korytar, P., De Boer, J., Gonzalez, M.J. (2005). Enantiomeric separation of chiral polychlorinated biphenyls on P-cyclodextrin capillary columns by means of heart-cut multidimensional gas chromatography and comprehensive two-dimensional gas chromatography applications to food samples. J. Sep. Sci. 28, 163-171. 

Liquid cathode lithium cells, 3 464-466 Liquid chromatography, 4 618—620 6 375, 440-468 14 233. See also High performance liquid chromatography Ion chromatography applications, 4 625-626 6 457-465 brief overview, 6 384-388 column switching, 6 446-447 columns, 4 623 derivatization, 6 447—448 detectors, 4 622-623 6 386-387, 448 52... 

The 3,4-di-O-benzylated D-fructopyran derivative (Scheme 26) would limit the possibilities for spiro-furan and -pyran derivatives. Application of the usual two-step process afforded with a 60% overall yield a mixture of OZTs in which the spiro-furan forms predominated (2 1 ratio) over the spiro-pyran forms. After column chromatography separation, acetylation allowed isolation of each epimer either a-furan (37%) and (3-furan (35%) forms as well as a-pyran (41%) and (3-pyran (27%) forms. 

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. 

Ripley BD, Braun HE. 1983. Retention time data for organochlorine, organophosphorus, and organonitrogen pesticides on SE-30 capillary column and application of capillary gas chromatography to pesticide residue analysis. J Assoc Off Anal Chem 66(5) 1084-1095. 

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