Polar extraction

Extraction and Extractive Distillation. The choice of an extraction or extractive distillation solvent depends upon its boiling point, polarity, thermal stabiUty, selectivity, aromatics capacity, and upon the feed aromatic content (see Extraction). Capacity, defined as the quantity of material that is extracted from the feed by a given quantity of solvent, must be balanced against selectivity, defined as the degree to which the solvent extracts the aromatics in the feed in preference to paraffins and other materials. Most high capacity solvents have low selectivity. The ultimate choice of solvent is deterrnined by economics. The most important extraction processes use either sulfolane or glycols as the polar extraction solvent. 

Its principles include polar extraction with acetone-water (2 1, v/v), homogeneous partitioning of the target molecules into an organic solvent, GPC cleanup on Bio-Beads, fractionation by adsorption column chromatography on silica gel (Si02) deactivated with 1.5% water and finally GC with various selective detection methods (NPD, BCD, FPD). 

Figure 5. Tomato cell suspensions exposed to peak 1 polar extract of spikerush culture. Plotted as relative fraction of cell volume over volume of medium vs. time.

Polar extraction Silica, diol, cyano, Polar functional groups, Nonpolar solvents, Nonpolar solvents, such... 

In 1965 Seshardri et al. described the isolation of an unknown terpenoid acid B obtained from the lichens of Lobaria retigera in the western Himalayas [8]. (Note that this annotation bears no relation to the subsequent nomenclature later defined by Corey and Shibata.) Four collections had been made in the summer of 1962 from under the Rutba plants in the Valley of Flowers (12,500 feet) and on the way to Hemkund Lokpal (13,500 feet) and from underneath rocks and from pine trees in Ganghariya (10,000 feet). The samples were subjected to a series of increasingly polar extractions (petroleum ether, diethyl ether, acetone). The unknown terpenoid acid B was present in all petroleum ether extracts, except that of the sample obtained from the Valley of Flowers, in compositions ranging from 0.47 % to... 

The seeds from the Indian neem tree, Azadirachta indica, are the source of two types of neem-derived botanical insecticides neem oil and medium polarity extracts. Neem seeds contain numerous azadirachtin (Fig. 9) analogs, but the major form is azadirachtin and the remaining minor analogs are likely to contribute little to the overall efficacy of the extracts. Typically, solvent partitions or other chemical processes are required to concentrate this active ingredient to the level of 10% to 50% seen in the technical grade material used to produce commercial products. 

All methanol extract and one-less polar extracts of the species examined killed snails at 1.000 ppm within 24 h (Table 7). 

Neem extracts, pure constituents (i.e. azadirachtin) and formulated products showed positive results against Tetranichus mites [279-283]. Less polar extracts were considerably more toxic than polar ones or cold-pressed neem oil or commercial neem oil, and reduced the fecundity of the mites on treated plants and the survival of nymphs hatched from treated eggs application of pentane extract or neem oil in sublethal concentrations, caused growth disrupting effects on the nymphal stages and ovicidal effects. Quantification of the insecticidal substance azadirachtin in the extracts revealed that this compound was not the most active principle against the mites [284]. 

Optional) If the sample contains highly polar odorants, set up the extraction system again and put the extracted aqueous phase back into the extraction flask. Add 600 ml ethyl acetate and repeat steps 2 through 6. This is the polar extract. 

Fig. 4 (a) Polar extracts of fish pan fried and barbecued for 9 min. Pan frying at 200°C produced more MelQx (peak B) than barbecuing for the same time at 270°C (peak C). MelQx peak C (< 1 ng/g) illustrates the DL of the method. Online recorded UV spectra from MelQx peaks are shown at the right, (b) Polar and apolar extracts of fish barbecued per side at 270°C. These samples contained detectable PhIP in the polar extract (left) and AaC, norharman, and harman in the apolar extract (right). (From Ref. 177.)... 

Percent Vanadium in Each Molecular Weight Category of Vanadyl Compounds in the Four Heavy Crude Petroleums and Their Asphaltenes, Maltenes, Asphaltene Polar Extracts, and Extracted Asphaltenes by 50/100/1000 A SEC-HPLC-GFAA Analysis"- ... 

The results are not what one would expect based upon a solvation model of extraction. Since the herbicides are more soluble in non-polar solvents (Table IX), one would expect that a non-polar extraction fluid, such as C02 or C02... 

Study of polar extraction solvents comparison of extraction solvents... 

FIGURE 5 (A) UHPLC ESI+chromatogram of the polar extract of postmortem brain tissue. (B) The scores plot displaying the separation between the two sam-... 

A recent study has identified the substances that induce metamorphosis in the sea urchin Holopneustes purpurascens.n Although adult urchins live in the canopy of several different subtidal algae, including the red alga Delisea pulchra and the kelp Ecklonia radiata, recent recruits were found predominantly on D. pulchra. Competent larvae metamorphosed in the presence of D. pulchra, seawater surrounding this alga, and polar extracts of D. pulchra. The cue for metamorphosis was isolated by reverse-phase HPLC from an aqueous partition of the MeOH extract of D. pulchra. It was characterized primarily by NMR and found to be a water-soluble complex... 

The polar extracts are more difficult because they contain conjugates of pesticides together with normal natural products, like sugars, which are closely related to the conjugates. Furthermore, these solutions are likely to contain natural products which have become radiolabeled as a result of... 

Both cell culture with a lipophilic extraction phase and with a polar extraction phase have been reported to be helpful for the accumulation and detection of secondary substances [7,8]. Plant cell cultures release lipophilic and volatile substances such as ethylene, ethanol, and acetaldehyde. The addition of a lipophilic phase to the culture medium can be used as a means of accumulating and detecting these substances. Maisch et al. [8] found that the addition of XAD-4 resin to Nicotiana tabacum cultures enhanced the production of phenolic secondary metabolites several times compared to the adsorbent-free control. Kim and Chang [9] reported in situ extraction for enhanced shikonin production by Lithospermum erythrorhizon. When n-hexadecane was added to the cultivation, higher specific shikonin productivity was obtained than that from the cultures of free cells without extraction. They also suggested that n-hexadecane addition at an early stage in calcium alginate immobilized cell cultures was effective for shikonin production. Most of the produced shikonin was dissolved in n-hexadecane, so it would reduce the costs for shikonin separation. 

The wipe sample from the organic solvent extraction is then extracted with polar solvent (e.g. water, methanol, or acetonitrile) in the manner described above for nonpolar solvent (Figure 3, fraction 2A). For analysis with GC and GC-hyphenated techniques, the polar extract must be derivatized. A part of the acetonitrile extract can be silylated with BSTFA in the same way as the organic extract of the wipe sample however, methanol or water extracts... 

An appropriate portion of the polar extract of the wipe sample is prepared for analysis of the sample for lewisite 1, lewisite 2, and lewisite oxide (Figure 3, fraction 2D). The pH of the sample is adjusted with hydrochloric acid to pH 2, the sample is filtered, and 0.1ml of freshly prepared solution containing DMT 5 mg ml 1 in acetone is added. The sample vial is shaken vigorously and allowed to stand for 10min, lml of n-hexane is added, and the sample is shaken vigorously for 30 s every 10 min for 30 min. The hexane fraction is allowed to separate. The top hexane-water layer is transferred to a new vial and centrifuged. After centrifugation, the hexane fraction is separated, dried, and submitted for analysis. 

The paint, rubber, or other polymeric sample from the organic extraction, or a new portion of the original sample is extracted with distilled, deionized water in the manner described above for an organic solvent (Figure 5, fraction 2). This sample is analyzed for polar CWC-related chemicals. For analysis with GC and GC-hyphenated techniques, the polar extract must first be derivatized an appropriate part of the extract is evaporated to dryness on a rotary evaporator at 50 °C and 366 mPa for ca. 30 min. Then 0.5 ml of acetonitrile and 0.5 ml of BSTFA are poured over the evaporation residue and the silylation mixture is heated at 60 °C for 30 min to complete the silylation (fraction 2A). This sample is analyzed for polar CWC-related chemicals such as thiodiglycol, aminoalcohols, and polar alkylphos-phonic and alkylthiophosphonic acids. The evaporation residue may also be methylated the residue is dissolved in dry acidic methanol and the solution is methylated with diazomethane. This sample is analyzed for polar alkylphosphonic and alkylthiophosphonic acids. 

Figure 2. Distribution according to polarity (extractability of Aa-TIIC) of in vivo metabolites in hydrolyzed and unhydrolyzed Rhesus urine nonpolar neutrals = extractable with hexane at natural pH weakly polar neutrals = extractable with ether at pH 12 weakly polar acids — extractable with ether at pH 2 moderately polar acids = extractable with ethyl acetate at pH 2 highly polar acids = extract-...

Extraction of free phytosterols and steryl conjugates In principle, sterols are extracted with common organic solvents like hexane, heptane, methanol, and chloroform, but the more polar conjugates (SFs, SGs, and ASGs) require more polar extraction solvents to be quantitatively extracted from plant sample materials. Therefore, if only selected class(s) of steryl conjugates with similar polarity are analyzed, one solvent extraction can be sufficient. However, for a total lipid extraction for a later fractionation to the individual classes of phytosterol conjugates, one must utilize combinations of extraction solvents to ensure maximum recovery. 

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