Neutrals fraction chromatographic separation

PAHs were isolated from the crude extracts by a two-step procedure. The neutral fraction was separated by simple acid-base partitioning and then chromatographed on a silica gel column. The column was first eluted with TO ml of hexane. Subsequent elution with 200 ml of hexane containing 5 dichloromethane gave the PAH fraction. The solvent was carefully evaporated to produce the dry extract. The PAH fraction of SI and S2 were designated as S1-C2 and S2-C2, respectively. 

Chromatographic separation of free nucleotides from various sources usually gives the glycosyl esters of uridine 5 -pyrophosphate in three fractions, containing fhe derivatives of neutral monosaccharides, uronic acids, and 2-acetamido-2-deoxyglycoses, respectively. 

For the analysis of semivolatile organics, a column performance test for base/neutral and acid fractions must be performed to test the efficiency of chromatographic column for separation of the analytes. For the base/neutral fraction, inject 100 ng of benzidine and determine the benzidine tailing factor which must be less than three. Similarly, for acid fraction, inject 50 ng of pentachlorophenol and calculate its tailing factor which must be less than five. 

After 30 years of study, the gypsy moth sex attractant was isolated, characterized, and synthesized in 1960 (25). To isolate the attractant, it was necessary to clip the last two abdominal segments of many virgin female moths, separate the neutral fraction from a benzene extract of the abdomens, and either chromatograph by a tedious process on adsorbent columns, or what is more satisfactory, dissolve the... 

The light and medium dark lithotypes are widely separated in their oxidation product yields (Table 1). Chromatographic separation and analysis of their Neutrals, Acids 1 and Acids 2 fractions generally resulted in the widest variation in structural type and yield for the lithotype series. The results of these analyses are depicted in Tables 2 and 3 along with Figure 6A, B and C. 

Figure 6A Chromatographic separation, of the Neutrals fractions from the Light and Medium Dark Lithotypes. Numbers directly above eluted peaks identify the chain length of these even n-alcohols. Numbers below the chromatogram refer to the carbon chain length of the corresponding terminally hydroxylated diols. (X) is identified as 1,9-dihydroxy-dodecane.

The production of HMF was even driven forward to a pilot plant scale including the work up and isolation of the pure product [34]. It consists essentially of the following steps (1) dehydration of fructose to HMF in aqueous solution (0.5 M) under sulfuric acid catalysis at 150°C (2) cooling and subsequent neutralization (CaOH or CaCOa) and filtration (3) chromatographic separation of the filtrate on calcium-loaded strong acidic cation exchanger resin and (4) cooling crystallization of the HMF fraction with overall HMF yields of 40-50%. 

A schematic diagram of the column chromatographic separation method used to isolate APAH-rich fraction is shown in Figure 32.8. Briefly, the nitrogen polycyclic aromatic compounds (N-PACs) were eluted with chloroform from neutral aluminum oxide. Then, the APAHs were isolated from most of the other N-PAC by silicic acid adsorption chromatography. 

Fig. 132. Analysis of the eluate fractions of a column-chromatographic separation of Hydrolagus colliei liver oil. I neutral plasmalogens II alkyl diglycerides III triglycerides (cf with Fig.. 131, No. 2)...

The acidic, basic and neutral fractions are individually analyzed. The neutral fraction by itself consists of so many compounds that in most cases not even a gas chromatographic column with the highest resolving power is able to separate them into individual peaks. Thus, separation of the neutral fraction is advisable and is usually achieved by liquid chromatography, or preparative gas or high performance liquid chromatography. A preliminary separation of aroma extracts is achieved... 

A gas chromatographic method is described in this work for the analysis of tetradecane-l,4-sultone (C14 5-sultone) and the combination of 2-chloro-tetradecane-l,3-sultone (C14 2-chloro-y-sultone) and l-tetradecene-l,3-sultone (C14 unsaturated y-sultone) in neutral oils isolated from alkenesulfonate. Samples of the neutral oil are diluted in hexane and injected directly into the gas chromatograph. Quantitative data are obtained by comparison to known amounts of the respective sultones. Through the use of silica gel column chromatography followed by GC of collected fractions, separation and individual quantitation of the 2-chlorotetradecane-l,3-sultone and l-tetradecene-l,3-sultone can be obtained. 

After the extrachon of total lipids from four different genotypes of flax seed (Linum usitassimum) differing markedly in their acyl composihon, PTLC was used for the isolahon of different lipid classes in the neutral lipid frachon [69]. Application of planar chromatographic methods, including PTLC, in the separahon of food lipids has been reviewed with 40 references by Olsson [70]. The polar lipid fraction of niger seed (Guizotia abyssinica Cass.) collected from different regions of Ethiopia could be separated by PTLC on silica gel [71]. 

Alkaline hydrolysis, in some cases carried out with the help of a microwave system, followed by extraction with organic solvents (normally w-hexane and diethyl ether), allows neutral and acidic compounds to be separated into two fractions, and the chromatographic data to be more easily interpreted. 

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