Neutralization, fraction

Two neutral fractions were also obtained (d) C34H3g(6o), b.p. 260°, 1-4805, and (e) pimanthrene, C79H74, identical with the hydrocarbon obtained from staphisine (Jacobs and Huebner). ... 

The residue from the neutral fraction is crystallized from aqueous acetone to yield 3.4 g (94%) of 3a,21,21-trihydroxy-5j -pregnane-ll,20-dione, mp 153-155°. 

The mixture is boiled for one hour, diluted with water and, after cooling, is treated twice with ether in order to eliminate the remaining neutral fractions. The aqueous layer is precipitated by means of 15 cc of acetic acid. 2.1 g of raw acid are obtained. After effecting two Crystallizations in 10 parts of acetic acid mixed with 3 parts of water, fine needles are obtained which are grouped in rosettes and melt at 131.5° to 132.5°C. 

This ether wash may be combined with the main neutral fraction and distilled to obtain 29-30 g. (33-34%) of 2-(dichloro-methylene)bicyclo[3.3.0]octane, b.p. 53-56° (01 mm.), n25d 1.5179-1.5182 (pure by gas chromatography) (column as in Note 8, 125°, retention time 4 minutes). 

The anion fraction, with unadjusted pH, showed significantly greater inhibition than the cation and neutral fractions (Table VIII). 

Figure 2. Separation of Fraction HI (see Figure 1) to Subfractions by Ion Exchange Chromatography (A = Acid, B = Base, and N = Neutral Fractions).

Figure 8.4 Total ion current chromatograms of the (a) acidic and (b)neutral fractions of a sample collected from an amphora recovered in Fayum. DDA, didehydroabietic acid DA, dehydroabietic acid 70DA, 7 oxo dehydroabietic acid 70A, 7 oxo abietic acid 15Hy70DA, 15 hydroxy 7 oxo dehydroabietic acid 5HyDA, 15 hydroxy dehydroabietic acid R, retene MDA, methyl dehydroabietate. Slf internal standard, hexadecane IS2, internal standard, tridecanoic acid...

GC/MS has also been used to investigate acidic and neutral fractions (after alkaline hydrolysis, separation and trimethylsilylation) of a resinous sample collected from a flint flake dated back to the lower Palaeolithic (roughly 200 000 BC) and recovered near Arezzo in Italy [11]. The results show that the organic material recovered on the flint flake was a pitch obtained from birch bark by a pyrolysis type process. In fact, the main components of the acidic fraction are a series of linear a,oo-dicarboxylic acids ranging from 16 to 22 carbon atoms and a series of oo-hydroxycarboxylic acids ranging from 16 to 22 carbon... 

Figure 8.9 Total ion current chromatograms of (a) acidic and (b) neutral fractions of the sample collected from the Palaeolithic flint flake, taOHCx y are hydroxy fatty acids of chain length x with the hydroxy group at position cu and with y double bonds a,uidiCx y are a, uj dicarboxylic fatty acids of chain length x and with y double bonds...

It was soon recognized that tyrothricin was not a pure compound but could be separated into a neutral fraction called gramicidin and a basic fraction called tyroci-... 

This system was studied by Schwartz. Toluene at 10 ppm, nitric oxide at 1 ppm, and nitrogen dioxide at 1.2 ppm were irradiated with ultraviolet lamps in a 17-m batch reactor for 270 min. Collected aerosols were successively extracted with methylene chloride and then methanol. The methylene chloride extract was fractionated into water-soluble and water-insoluble material, and the latter fraction was further divided into acidic, neutral, and basic fractions. The acidic and neutral fractions were analyzed by gas chromatography and chemical-ionization mass spectrometry the compounds identified are shown in Figure 3-7. The two analyzed fractions represented only about 5.5% of the total aerosol mass. It is noteworthy that classical nitration of an aromatic ring appears to... 

Active compounds have been found in the neutral fraction of buck hair extract (Over etal, 1990). The carbonyl group and a hydroxyl group appear to be important for the biological activity (Claus etal, 2001). 

Steam volatile aroma constituents of CA094 roasted coffee-neutral fraction. Z Lebe-nsm-Unters Forsch 1976 160 277. 

Epstein-Barr virus early antigen induction. Methanol extract of the dried leaf, in cell culture at a concentration of 1 pg/mL, was inactive. The assay was designed for tumor-promoting activity . Two diastere-oisomers of 2,7,1 l-cembratriene-4,6-diol (a- and 3-CBT) from the neutral fractions of cigarette smoke condensate, in Raji cells, produced potent inhibitory effects on the induction of Epstein-Barr virus (EBV)-EA by 12-0-tetradecanoylphorbol-13-acetate (TPA). The doses of a- and P-CBT required for 50% inhibition of EBV-EA induction by TPA were 7.7 and 6.7 mg/mL, respectively. Application of a- and P-CBT to mouse skin before treatment with TPA, inhibited TPA-induced ornithine decarboxylase activity in a dose-dependent manner. Application of 16.5 pM/mouse of a- and p-CBT resulted... 

Eor obtaining neutral fraction the column was eluted with water firstly. The acidic fractions were obtained by elution of linear NaCI gradient (0-1.4 M) in water. The carbohydrate elution profile was determined using the phenol-sulphiric acid method, finally two column volumes of a 2 M sodium chloride solution in water were eluted to obtain the most acidic polysaccharide fraction. The relevant fractions based on the carbohydrate profile were collected, dialysed and lyophilized. 

Glucose, galactose, arabinose (in neutral fraction) Uronic acids (Both galacturonicand glucuronic acid), rhamnose, galactose, arabinose and glucose (in acidic fraction) [22]. 

Solvent extraction of the sample is also frequently used in the analysis of particulate matter. Through the appropriate choice of solvents, the organics can be separated into acid, base, and neutral fractions, polar and nonpolar fractions, and so on. This grouping of compounds according to their chemical properties using extraction techniques simplifies the subsequent analysis. Each fraction can then be analyzed by GC-MS, with the GC retention time and the mass spectrum used for identification and measurement. 

Analysis of glycosaminoglycan hydrolyzates is often complicated by the presence of basic and acidic glycoses, in addition to neutral monosaccharides. Adsorption chromatography on silica gel was used to classify such a hydrolyzate, and the neutral fraction was shown to contain D-glucose, D-galactose, and D-mannose.288 Separation on ion-exchange resins may also be used.51,149 The resolution of the acidic and basic fractions is discussed in Sections IX (p. 71) and X (p. 78). 

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. 

These must be glycerol free. A solvent extraction procedure must be used prior to GC-MS [2, 5, 6]. If the sample is prepared with ion-exchange chromatography, the glycerol will remain in the neutral fraction and not be detected by GC-MS [2, 5]. Hydrochloric acid (5 N), pH paper, sodium sulfate (anhydrous), ethyl acetate (free of contaminants), diethyl ether (anhydrous, peroxide-free, and free of contaminants except 2,6-ditertbutylcresol, which is an antioxidant found in all ether), and malonic acid (26.25 mg/50 ml methanol). 

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