Chromatographic methods to separate

Also important is the use of the modem chromatographic methods to separate and identify individual components in commercial cmde shale oil. The use of efficient gas chromatographic columns coupled with ancillary techniques such as mass spectrometry and vapor-phase IR spectroscopy allows the identification of individual shale oil components. A principal part of this study is the comparison of diflFerent types of open tubular columns for the separation of the alkane-alkene fraction of shale oil WCOT, SCOT, and PLOT columns are examined. Gas chromatographic separation of shale oil acids and bases also is performed allowing the identification of these components. The potential utility of subtractive pre-columns in HPLC analysis is illustrated also. 

Maruyama O used a ring oven paper chromatographic method to separate meperidine and normeperidine from the free acids. 

The number of experimental studies in the literature on this topic is even smaller than for conductivity and vapor pressure data. All studies found are from the period between 1955 and 1959. Studies using chromatographic methods to separate the polyphosphoric acid species were performed by Higgins and Baldwin, Jameson, and Huhti and Gartaganis [43-45]. A formal approach using models from polymer science was presented by Westman and Beatty [46]. 

None of these studies have lead to significant improvements in doing the MALDI-ms of polymers with high polydispersities. Generally, this problem has been overcome by coupling MALDI-tof-ms to various chromatographic methods to separate polymers. 

Tsuji and Goetz24 developed a quantitative high performance liquid chromatographic method for separating and measuring erythromycins A, B, and C, their epimers and degradation products. This method uses a /iBondapak Ci 8 reverse column with acetonitrile-methanol-O.2m ammonium acetate-water (45 10 10 25) as solvent. The pH and composition of the mobile phase may be adjusted to optimize resolution and elution volume. The authors utilized the procedure on USP reference standard and report a relative standard deviation of 0.64%. 

Chromatographic methods of separation are distinguished by their high selectivity, that is their ability to separate components of closely similar physical and chemical properties. Many mixtures which are difficult to separate by other methods may be separated by chromatography. The range of materials which can be processed covers the entire spectrum of molecular weights, from hydrogen to proteins. 

In choosing suitable methods to separate a given mixture of compounds, the general characteristics favouring a chromatographic method are ... 

Analytical methods to separate and quantify individual isomers of metolachlor and its metabolites are imperative to accomplish this investigation. Chromatographic separation of metolachlor and its metabolites is complicated due to the existence of several rotational isomers for each compound. Thus, these compounds will be fractionated... 

ISEC, which was introduced by Halasz and Martin in 1978 [119], represents a simple and fast method for the determination of the pore volnme, the pore size distribution profile, and the spe-cihc snrface area of porous solids. Generally, ISEC is based on the principle of SEC. SEC, also referred to as gel permeation or gel filtration chromatography, is a noninteractive chromatographic method that separates analytes according to their size by employing a stationary phase that exhibits a well-dehned pore distribution. 

C. Q. Hu, S. H. Jin, and T. M. Wang, The chromatographic, behavior of cephalosporins in gel filtration chromatography, a< novel method to separate high molecular weight impurities, /. Pharm. Biomed. Anal., 77 530 (1994). 

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