Hexane extractable material

Table II shows data obtained by sequential hexanes and ethanol extractions of the desilylated networks. Attempts to extract the networks prior to desilylation failed because the samples swelled to such a great degree that they lost their mechanical integrity and disintegrated. The amount of hexanes extractable material is less than 3% in all cases which indicates high copolymerization yields. Ethanol extractables were not determined because the presence of the byproducts of the desilylation, which are in the ethanol, would have given artificially high readings.

Method 1664 n-Hexane Extractable Material (HEM) and Silica Gel Treated n-Hexane Extractable Material (SGT-HEM) by Extraction and Gravimetry (Oil and Grease and Total Petroleum Hydrocarbons) Monitoring Trace Metals at Ambient Water Quality Criteria Levels Briefing Book... 

Freon-extractable material is reported as total organic material from which polar components may be removed by treatment with silica gel, and the material remaining, as determined by infrared (IR) spectrometry, is defined as total recoverable petroleum hydrocarbons (TRPHs, or total petroleum hydrocarbons-IR). A number of modifications of these methods exist, but one particular method (EPA 418.1 see also EPA 8000 and 8100) has been one of the most widely used for the determination of total petroleum hydrocarbons in soils. Many states use or permit the use of this method (EPA 418.1) for identification of petroleum products and during remediation of sites. This method is subject to limitations, such as interlaboratory variations and inherent inaccuracies. In addition, methods that use Preon-113 as the extraction solvent are being phased out and the method is being replaced by a more recent method (EPA 1664) in which n-hexane is used as the solvent and the n-hexane extractable material (HEM) is treated with silica gel to yield the total petroleum hydrocarbons. 

A cELISA using LLNL-Hept-2. capable of detection heptachlor and other related chlorinated cyclodiene insecticides in spiked meat, fish and dairy samples was developed. Our cleanup method did not remove all of the substance(s) that interfered with the cELlSA. Such substances were observed in the hexane extracted material from all three matrixes investigated. Our data suggests that the beef fat has the highest level of interfering substances and heavy dairy cream the lowest level. The exact nature of these substances are not known. 

Method 1664 N-Hexane Extractable Material and Silica Gel Treated N-Hexane Extractable Material by Extraction and Gravimetry. Washington, DC Office of Water Engineering and Analysis Division, 1994, EPA-821-B-94-004. 

The secretion of the East African species A. messinae contains the eudesmane but the minor component is limonene (Meinwald etal., 1978). Of two sympatric species, A. unidentatus produces mainly methyl ketones, principally 2-tridecanone, and A. lonnbergianus has no hexane-extractable material. The North American species, A. wheeleriproduces a sesquiterpene hydrocarbon only (Prestwich, 1979b), while the Australian species, A. herbertensis and A. laur-contain monoterpene hydrocarbons, the former terpinolene (>98%) and a-phellendrene and the latter limonene and -pinene (Moore, 1968). 

To the residue is added 600 ml. of ethylene glycol, followed by 40 ml. of concentrated sulfuric acid. The resulting mixture is heated under vigorous reflux for 20 hours, and then cooled and transferred to a 2-1. stainless-steel or copper flask. To this material is added a solution prepared from 325 g. of potassium hydroxide, 300 ml. of water, and 300 ml. of 95% ethanol. The resultant solution is heated under reflux for 1 hour, and then cooled and transferred to a 5-1. separatory funnel, where it is diluted with 3 1. of water and acidified with 600 ml. of concentrated hydrochloric acid. The organic liquid which separates is diluted with 300 ml. of hexane and separated from the aqueous layer, which is extracted three additional times with 300-ml. portions of hexane. The hexane extracts are washed to pH... 

Japenga et al. [56] determined polychlorinated biphenyls and chlorinated insecticides in River Elbe estuary sediments by a procedure in which the sediments were pretreated with acetic acid, mixed with silica and Soxhlet-extracted with benzene/hexane. Humic material and elemental sulphur were removed by passing the extract through a chromatographic column containing basic alumina, on which sodium sulphite and sodium hydroxide were adsorbed. Silica fractionation was followed by gas chromatography to analyse chlorinated pesticides, polychlorinated biphenyls and polyaromatic hydrocarbons. Recovery experiments with standard solutions gave recoveries of 90-102%. 

Extraction of the product with refluxing n-hexane for 24 hours gave 21.0 grams of hexane-insoluble material and 0.5 gram of soluble material. The add-on was therefore 5%. 

Et2AlCl Catalyst. Under the same conditions as above 20 grams of PVC and 2 grams of cis-1,4-polybutadiene, prepared with an alkyl-aluminum-titanium tetraiodide catalyst system (95% cis-1,4 content, intrinsic viscosity at 25°C in benzene 2.2) in 200 ml chlorobenzene were allowed to react in the presence of 2 mmoles of Et2AlCl at 5°-10°C for 60 minutes. The reaction product was isolated by precipitation in methanol and dried to yield 22.0 grams of modified poly (vinyl chloride). Hexane extraction under reflux for 24 hours removed 8% of hexane-soluble material. 

One kg of the fine powdered marijuana plant material [average % of THC was about 5.21%] was macerated with 6 L hexanes (Hexanes GR from EM Sciences) in a percolator (9" in diameter from the top and 20" long, cone shaped) for 24 hours at room temperature and filtered. The macerate was reextracted with 5 L hexanes for another 24 hours. The hexane extracts were combined and evaporated under reduced pressure at low temperature to give 110.7 g residue (11.07% extractives). The % of THC in the hexane extract was 41.21%. 

A 4 ml sample of milk was hydrolyzed and extracted according to the urine procedure. The hexane extract residue was dissolved in 2 ml methanol and centrifuged at ambient temperature, removing white lipid material. The methanol was evaporated under nitrogen and the residue reconstituted in 50 pi hexane. 

Canola Oil occurs as a light yellow oil. It is typically obtained by a combination of mechanical expression followed by n-hexane extraction, from the seed of the plant Brassica juncea, Brassica napus, or Brassica rapa (Fam. Cruciferae). The plant varieties are those producing oil-bearing seeds with a low erucic acid (C22 i) content. It is a mixture of triglycerides composed of both saturated and unsaturated fatty acids. It is refined, bleached, and deodorized to substantially remove free fatty acids phospholipids color odor and flavor components and miscellaneous, other non-oil materials. It can be hydrogenated to reduce the level of unsaturated fatty acids for functional purposes in foods. It is a liquid at 0° and above. 

Lipid mixtures have remarkable ability to carry nonlipid materials into organic solvents, partly by way of ionic interactions. Thus, hexane extracts of blood serum contain urea, sodium chloride, and amino acids, and hexane extracts of soybeans contain the sugars rafGnose and stachyose. 

Some potential extractable chemicals from packaging materials are water soluble, while others are soluble only in nonpolar environments. The USP includes physicochemical tests for plastics based on water extracts, while water, alcohol, and hexane extracts are required for polyethylene containers under controlled temperature and time parameters (70°C for 24h for water and alcohol and 50°C for 24h for hexane). 

Confirmation of the identity of pentachlorophenol (PCP) in samples of human blood, urine, tissue, clothing, and bedding materials has been reported (II), utilizing combined gas chromatographic-mass spectro-metric analysis of hexane extracts of these substrates. 

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