Benzene lipid removal

Tomy et al. [ 14] extracted PCAs from fish and sediments by using DCM extraction, lipid removal by SX-3 Biobeads gel permeation chromatography (GPC) [53], and cleanup with Florisil column chromatography. Fractionation on Florisil was achieved by eluting with hexane (FI), which eluted all the PCBs, chlorinated benzenes, 4,4 -DDE, then with (15 85) DCM/hexane (F2), and finally with (1 1) DCM/hexane (F3). Fractions F2 and F3 contained PCAs along with 4,4 -DDT, toxaphene, cis- and frans-chlordane and other more polar organics, such as heptachlor epoxide and dieldrin. The mean percentage recovery of PCAs for this method was 85 %. 

It is a lipophilic compound which removes intercellular lipids that are covalently linked to the cornified envelope surrounding epithelial cells [3]. It also enhances penetration of other agents. Resorcinol (m-dihydroxy benzene) is structurally and chemically similar to phenol. It disrupts the weak hydrogen bonds of keratin [4]. Lactic acid is an alpha hydroxy acid which causes corneocyte detachment and subsequent desquamation of the stratum corneum [5]. 

When liposomes are prepared from a molecular mixture of lipid components it is important that all lipids be homogeneously dissolved in an organic solvent in order to obteiin bilayers with evenly distributed lipids after hydration. For example, the solubilities of phosphatidylcholine and cholesterol in chloroform are similar their solubility in benzene differs. Upon removal of benzene from the lipid solution an inhomogeneous lipid film is formed on the glass wall and... 

Preliminary purification of a starting band contaminated with plant oil should be performed by predevelopment with a nonpolar solvent such as benzene or n-heptane, delivered from the eluent container. Weakly retained ballast substances (e.g., lipids) move with the solvent to the edge of the adsorbent layer, covering the glass plate where the volatile solvent evaporates. The contaminants can then be removed (scraped out with the adsorbent) from the layer or adsorbed on the strip of blotting paper placed on the upper edge of the layer. 

In some instances, it is desirable to remove lipids and other so-called extractives before proceeding with polysaccharide separation. This removal is generally accomplished through Soxhlet extraction with an azeotropic mixture of ethanol and benzene.26 2 27... 

Lipids can be identified and quantified using thin-layer chromatography (TEC) and gas chromatography (GC) (Galliard, 1968). Extraction of lipids is achieved by homogenizing potato tubers with isopropanol in a blender, followed by a series of filtrations and extractions with chloroform-methanol (2 1). Chloroform is removed by rotary evaporation and the residue is redissolved in benzene-ethanol (4 1). This extract is passed through a DEAE-cellulose column, and the fractions collected are subjected to TEC on 250 p,m layers of silica gel G, using three solvent systems. Fatty acid methyl esters for GC analysis are prepared by transmethylation of the parent lipids, or by diazomethane treatment of the free fatty acids released by acid... 

Results from the reverse phase HPLC study suggested that since a preliminary extraction of plasma with petroleum ether was required to remove lipids, that a 1 ml sample of plasma could be extracted first at a neutral pH to remove I followed by acidification to pH 4 and extraction to remove VI. Indeed this was found to be practical. Thus to 1 ml of plasma could be added either d3 I or VIII, depending upon which assay method was to be used, as internal standard followed by extraction with petroleum ether. To the plasma would then be added 1 ml of pH 4 buffer and benzylbiphenyl followed by extraction with benzene-isopropanol. 

In this chapter, we consider humin to be the residue after successive extraction of sediments by benzene/methanol to remove lipids, dilute acid IN HCl), and 0.5N NaOH. In marine sediments, further treatment with concentrated HF/HCl (1 1 v/v) is required to concentrate the organic matter by removal of mineral matter. This treatment will partially or totally hydrolyze polysaccharides and proteins while probably having little effect on the humic material (Hatcher et al., 1983a). 

The methods for hydrocarbon extraction and analysis are similar to those previously described (16,17,18). Sediment samples were soxhlet-extracted in methanol benzene (1 1) for 48 hr. Copper wool was placed beneath the thimble to facilitate drainage and removal of elemental sulfur. Lipids were partitioned into a pentane-benzene layer (3 combined washes) followed by a wash of saturated NaCl solution, dried overnight with Na2S04, and vacuum-evaporated to dryness. The extract was redissolved in pentane and fractionated by column chromatography on alumina over silica gel (both 5% deactivated with H20). Aliphatics were eluted with three column volumes of pentane, followed by three column volumes of benzene to elute aromatics. Only analyses of the pentane fractions are reported here. 

Isolation of the hydrocarbons from other lipids The total lipid extract may be subjected to removal of elemental sulphur by passage through an activated copper column (Blumer, 1957) and then to chromatographic separation on adsorbent columns or thin layer plates. For column chromatography, silic el is used with a short alumina bed on the top of the silic el. Both adsorbents should be partially deactivated by the addition of water (2—5%) to prevent the formation of artifacts (Blumer, 1970). Elution with a non-polar solvent such as hexane or pentane and subsequently with mixtures of non-polar and polar solvents, e.g. benzene and methanol, permits the isolation of several fractions containing saturated, unsaturated, aromatic hydrocarbons and more polar compounds (methyl esters, alcohols, acids, phenols and heterocyclic compounds). The interference from esters encountered in the isolation of aromatic hydrocarbons can be avoided prior to separation by saponification of the esters of fatty acids, which are easily removed. 

Extraction of human hair with fat solvents removes approximately 1 to 9% matter. Ethanol, a solvent that swells hair, removes more lipid from hair than nonswelling solvents like benzene, ether, or chloroform. Hair consists of surface (external) lipid and internal lipid. In addition, part of the internal lipid is free lipid, and part is structural lipid of the cell membrane... 

The most common mixture is that of chloroform and methanol. A typical procedure is that of Bligh and Dyer (1959) where a one-phase methanol system (chloroform-methanol-water, 1 2 0.8, by vol.) rapidly extracts lipids from most tissues and the extract is then diluted with 1 vol. each of chloroform and methanol to yield a two-phase mixture. The upper (aqueous) phase contains water-soluble contaminants while the lower phase contains lipids. Water-soluble contaminants can also be removed from solutions of lipids in organic solvents by passage through Sephadex columns (Rouser et ai, 1967). After rotary evaporation of the solvent, traces of water may remain with the lipid. These can be removed by azeotropic distillation with benzene. 

Succinic anhydride added to a dried soln. of j -estradiol in benzene containing 1% pyridine, refluxed ca. 24 hrs., cooled to room temp., excess succinic anhydride removed by filtration, the solvent removed on a flash evaporator, the residue dissolved in methanol, and stirred overnight with excess aq. suspension of NaHCOg to hydrolyze the phenolester group estradiol 17/5-hemisuccinate. Y 89%. T. O. Yellin, J. Lipid Res. 13, 554 (1972). 

Vitride reagent (0.5 mL) is added to the lipid (1 to 10 mg) in diethyl ether-benzene (2.5 mL 4 1, v/v) in a test-tube, and the solution is heated with occasional shaking for 30 min at 37°C. On cooling, water-ethanol (10 mL 5 1,v/v) is added cautiously, then the products are extracted with diethyl ether (3 x 6 mL portions) hexane (10 mL) is added and the solution is dried over anhydrous sodium sulfate. After filtering, the solvent is removed from the combined extracts in a rotary evaporator. The samples are dissolved in a little chloroform and applied to a silica gel G TLC plate, which is developed in diethyl ether-hexane (4 1, v/v). The products are identified by their Rf values relative to standards, alkyl ethers migrating just ahead of the alk-1-enyl analogues, and they are eluted from the adsorbents with several volumes of diethyl ether."... 

The plant material is extracted by ethanol-benzene or chloroform-methanol to remove crude lipids cold/warm water to remove proteins and soluble carbohydrates ammonium oxalate-oxalic acid solution or aqueous ethylene-diamino-tetra-acetic acid-solution ( EDTA) to remove ->pectins acidic sodium chlorite to remove lignins. 

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