Squalene chromatography

Fritting From squalene Frontal Frontal chromatography Frontalin [28401-39-0] Froth Froth ers... 

Trihalomethanes. Wherever chlorine is used as a disinfectant in drinking-water treatment, trihalomethanes (THMs) generaUy are present in the finished water. The THMs usuaUy formed are trichloromethane (chloroform), bromodichloromethane, dibromochloromethane, and tribromomethane (bromoform). There are four main techniques for the analysis of THMs headspace, Hquid— Hquid extraction (Ue), adsorption—elution (purge—trap), and direct aqueous injection. The final step in each technique involves separation by gas—Hquid chromatography with a 2 mm ID coUed glass column containing 10 wt % squalene on chromosorb-W-AW (149—177 p.m (80—100 mesh)) with detection generaUy by electron capture. 

The condensable products were analyzed by gas-liquid chromatography using columns containing either l,2,3-tris(2-cyanoethoxy) -propane or di-2-cyanoethyl ether supported on Embacel. Hydrocarbons were determined on columns containing either dimethylsulfolane or a combination of propylene carbonate, squalene, and silicone oil on Embacel (3). 

The official method of analysis of steradienes in olive oil (Commission regulation (EC) No. 656/95) involves saponification of the oil with an internal standard of cholesta-3,5-diene, followed by extraction of the unsaponifiable fraction into hexane. The steradiene fraction is then separated from other hydrocarbons, such as alkanes and squalene isomers, by column chromatography on silica gel. Quantitative analysis is then performed by GC. 

Dubois, J.-E., Chretien, J.R., Sojdk, L. and Rijks, J.A. (1980a). Topological Analysis of the Behaviour of Linear Alkanes up to Tetradecenes in Gas-Liquid Chromatography on Squalene. J.Chromat., 194,121-134. 

Hydrogenation of CO2 was conducted using a pressurized fixed-bed, flow-type micro-reactor. One gram of pre-reduced catalyst was packed in the reactor tube and was pretreated in-situ at 623 K for 0.5 h in an H2 flow of 200 cm /min. After cooling to room temperature, the gas was switched to H2 - CO2 premixed gas ( H2 / CO2 = 3 ) containing 1% of Ar as an internal standard for GC analysis, and the reaction was carried out under appropriate conditions. The effluent gas was analyzed by on-line gas chromatography with a PEG-1500 column ( 3 m, FID ) and a 2 wt% squalene/active carbon column ( 3 m, TCD ). The tubings from the catalyst bed to the GC were kept hot to avoid condensation of all products. 

The stereoisomeric mixture of -hydroxyalkyl selenides resulting from the reaction of the a-selenoalkyllithium and the carbonyl compound has been often cleanly and easily separated into its constituents by liquid chromatography on silica gel (Schemes 124,133,134, and 170 172).200.206.222,226,229,258 59 jj,jg has, therefore, allowed the synthesis of each of the two stereoisomers of various di- and tri-substituted alkenes (Schemes 124,170 and 171 Scheme 172, a) and epoxides (Scheme 124 Scheme 172, b), which are otherwise obtained as intractable mixtures of stereoisomers through the conventional phosphorus or sulfur ylide methods. Last but not least, 2-lithio-2-methylselenopropane can be used as the precursor of various compounds bearing gem dimethyl substituted carbons, such as squalene, oxido-squalene, lanosterol and cholesterol. Use of commercially available perdeuterated or Ci or — 2 acetone allows the straightforward synthesis of the corresponding labelled compounds... 

H12. Holmes, W. L., and Stack, E., Gas chromatography of squalene, sterols and bile acid methyl esters. Biochim. Biophys. Acta 66, 163-165 (1962). 

The aim of this work was to develop a simple, environmentally sound and fltst method for the extraction and determination of squalene in an olive biomass using the PFE technique, and investigate if this technique could be a viable processing technology for the extraction of squalene from olive oil pomace. The effects of different solvents and mixtures of solvent, extraction temperature and extraction time were also evaluated for their influence on yield of squalene. Squalene in the olive biomass extracts were quantified by liquid chromatography with UV absorbance and fluorescence detection. In addition, the proposed method was used to determine the content of a-tocopherol in the olive biomass. 

The stationary phases used in reversed-phase chromatography, when it was first introduced, comprised of a non-polar substance (e.g. squalene) coated on to a silica-based support. These are now seldom used. The stability of such systems is low, because the forces holding, say, squalene to even a silylated silica are so weak that the stationary phase is easily washed from the column. A compromise reversed-phase packing material was developed, which had a polymeric hydrocarbon stationary phase on the support, but although quite successful it has now been superseded by a chemically bonded stationary phase of which some examples are discussed below. 

Sampling by glass or stainless steel beakers, filtration through Whatman No. 54 extraction at pH 2 with pentane, column chromatography on silica gel GLC mass spectrometry (MS) Buzzards Bay near-shore surface waters saturated straight-chain and branched paraffins, iso-prenoids and olefinic hydrocarbons isolation of straight-chain hydrocarbons from C 4 to C33 with a maximum around C25 to C28 without odd carbon predominance characterisation of pristane, phytane, a C21 hexaene and squalene Blumer(1970)... 

Pfizer reported the discovery of a new class of structurally complex alkyl carboxylic acids, as exemplified by CP-225917 and CP-263114 (Figure 20), that are weak and non-selective inhibitors of squalene synthase and FPTase. These compounds were isolated by acid base liquid-liquid partition, Sephadex LH20 chromatography and reverse phase HPLC from ethyl acetate extracts of an unidentified fungus that also produced zaragozic acid A [97]. 

The invertomers of (228) have been separated by gas chromatography on a column coated with optically active nickel(ii) bis-3-heptafluorobutanyl-(l/ )-camphorate in squalene. The chiral invertomers gave two distinct peaks, of intensity 1 1. 

Lu, H.T., Jiang, Y., and Chen, F., Preparative separation and purification of squalene from the microalga Thraustochytrium ATCC 26185 by high-speed counter-current chromatography, J. Chromatogr. A., 994, 37-43, 2003. 

Squalene is a precursor for steroid biosynthesis and may have cardioprotective and cancer-preventative properties. Though nuts are known to contain squalene, the limited literature available indicates that the pine nut contains a relatively low amount of squalene compared to other nuts [8]. Reverse-phase high-performance liquid chromatography (HPLC) analysis showed that pine nut oil had a squalene content of about 40mg/100g oil, which is approximately 23mg/100 nuts. Thus, they would not be a likely choice for a squalene-based nutraceutical however, this study did not report the species of pine nut measured, and variability between species of other compounds of interest may indicate that a different species could provide higher squalene content. 

These mathematical differences do not necessarily provide the clues on which the animals base their discriminatory responses. To test the communicatory content of only squalene and the butyrates, scent marks from males and females were subjected to gas chromatography, and the total eluate, containing all volatile material was collected and presented to the tamarins in choice tests. The animals preferred material from males over that from females, suggesting that the information on gender had been retained. However, when the eluate was collected in two fractions, one containing only the butyrates and squalene, the other... 

Only non-polar hydrocarbons like squalene [124] or /3-amyrene migrate on silica gel layers when n-hexane is used. Separation of comic Thin>Layer Chromatography, 2nd Edition... 

Gas Chromatography of Squalene, Sterols, and Bile Acid Methyl Esters... 

The earlier work of van Tamelen showed that squalene can be converted chemically to the 2,3-bromohydrin with hypobromous acid in aqueous glyme (210). In addition, JV-bromosuccinimide (NBS) treatment of squalene in water selectively gives the desired terminal bromohydrin. Treatment with ethanolic base results in the racemic 2,3-oxidosqualene. Using rat liver homogenate under standardized aerobic conditions, racemic 2,3-oxidosqualene finally gives rise to sterol fractions which can be purified by chromatography. 

Figure 3.176 Squalene CjqHjq, M 410, CAS 7683-64-9. Occurrence stationary phase in gas chromatography.

Guzman and co-workers [27] investigated whether it is possible to use waste tyre crumb as a replacement for zinc oxide as an activator in the sulfur vulcanisation of natural rubber (NR). They used the unsaturated organic compound squalene as a model compound for NR in their work, and followed the course of the vulcanisation reaction using the analytical technique high-performance liquid chromatography. The results confirmed that waste rubber crumb was an alternative to zinc oxide as an activator in the curing of NR compounds by sulfur-based cure systems. 

The species richest in squalene, C. uyato, is a small shark (up to 1 m long) that lives mostly at depths of between 500 and 1000 m in most seas of the world. The role attributed to the enormous amount of squalene, whose density is around 0.86, is to ensure buoyancy dose to zero at the usual depths where this shark lives. When the concentration of squalene is low, the liver oil is rich in diacylglyceryl ethers whose quantity can be modulated by the shark to regulate its buoyancy (Morris and Culkin, 1989), and triacylglycerols are also present. For detailed studies of the hydrocarbon composition of shark liver oils, see Nevenzel (1989) and Deprez, Volkman, and Davenport (1990). Squalene is used in the cosmetics industry and its hydrogenated derivative, squalane, is also used in cosmetics and serves as a stationary phase in gas chromatography. 

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