Extraction compounds

Stratifying water systems for selective extraction of thiocyanate complexes of platinum metals have been proposed. The extraction degree of mthenium(III) by ethyl and isopropyl alcohols, acetone, polyethylene glycol in optimum conditions amounts to 95-100%. By the help of electronic methods, IR-spectroscopy, equilibrium shift the extractive mechanism has been proposed and stmctures of extractable compounds, which contain single anddouble-chai-ged acidocomplexes [Rh(SCN)J-, [Ru(SCN)J, [Ru(SCN)J -have been determined. Constants of extraction for associates investigated have been calculated. 

Chlorofonn is too non-polar to dissolve the phenolic compounds under study, but it dissolves many of the monoterpenes, at least to some extent. Because the solubility of some monoterpenes into chloroform was low, different solvent/ solid ratios were tested. These were 50,20,10 and 5 1/kg of dry phloem. The extracts were bright yellow and the strongest colour was with the smallest solvent/solid ratio (51/kg). The colour of the solvent indicated that the solubility of the extractable compounds was not restricting the reaction even with the smallest solvent volume. The taste of the dry samples was evaluated by comparing them to the original phloem sample. The results showed that the mildest taste was in the phloem extracted with a solvent/solid ratio of 50 1/kg and 20 1/kg also had some effect on the taste. The taste of the chloroform-extracted phloem was stabile and it was the same after a week. 

PLC separations (Figure 16.13) started with toluene-ethyl acetate (95 + 5 v/v) as the mobile phase, whereas the final purification was achieved with cyclohexane-diethyl ether (80 -i- 20 v/v). The isolated and extracted compound matched the GC-MS of 24-norursa-3,12-dien-ll-one (compound 11) and is confirmed as an oxidized pyrolyzed boswelhc add. 

Lipids in living systems are by solvents extractable compounds. Among the lipids are the fatty acids, glycerides, steroids, terpenes, and complex lipids as lipoproteins. 

SFE is used mainly for nonpolar compounds [e.g. polychlorinated biphenyls (PCBs)]. Typically, small aliquots of soil (0.5-10 g) are used for extraction. The extraction solvent is a supercritical fluid, most commonly carbon dioxide, which has properties of both a liquid and gas. The supercritical fluid easily penetrates the small pores of soil and dissolves a variety of nonpolar compounds. Supercritical carbon dioxide extracts compounds from environmental samples at elevated temperature (100-200 °C) and pressure (5000-10 000 psi). High-quality carbon dioxide is required to minimize... 

Contaminants in recycled plastic packaging waste (HDPE, PP) were identified by MAE followed by GC-MS analysis [290]. Fragrance and flavour constituents from first usage were detected. Recycled material also contained aliphatic hydrocarbons, branched alkanes and alkenes, which are also found in virgin resins at similar concentration levels. Moreover, aromatic hydrocarbons, probably derived from additives, were found. Postconsumer PET was also analysed by Soxhlet extraction and GC-MS most of the extracted compounds (30) were thermally degraded products of additives and polymers, whereas only a few derived from the original contents... 

Analyte stability is another source of concern the chemical identity should be preserved all through the analytical process. This is not always guaranteed. Analytes may be oxidised or hydrolysed during extraction. Compound integrity can also suffer in the chromatographic column, through heat-induced decay. Extraction... 

Limonene (10) was the major extracted compound from pine resin (Pinus pinea). Since it occurs in other resins or plants it cannot be a biomarker. Longifolene (49), present in a lower amount, is more characteristic of a conifer resin. This sesquiterpene is particularly... 

Congratulations if you thought about the last one and if you realized that the analysis is made more difficult by the presence of large numbers of co-extracted compounds. Hence, a method involving extensive clean-up or purification of the initial extract will be required. In addition, the detection system selected will not only need to be able to measure very low concentrations but also be highly selective to ensure that positive signals are not obtained from co-extracted analytes. 

Chromatographic conditions should be optimized wherever possible to achieve baseline separation of the analyte peak from other peaks produced by co-extracted compounds. The retention time of the analyte should be at least twice the column... 

The volatile substances were extracted from portions of 0. lg hair using solid-phase micro extraction (SPME). The method uses a fibre coated with an adsorbent that can extract organic compounds from the headspace above the sample. Extracted compounds are desorbed upon exposure of the SPME fibre in the heated injector port of a gas chromatograph (GC). 

The methods used for making pigments from these and other natural dyes were more like recipes than scientific procedures and were probably derived from the work of alchemists and herbalists. The former spent their lives trying to prepare gold by dissolving all kinds of cheap substances in acids and then re-precipitating them (hence their discovery of many precipitants), while the latter sought to extract compounds of medicinal value from plants and some of their extracts must have included natural dyes. 

Because no pretreatment of the samples was carried out, the peaks present in the total ion current trace reflect components generated by pyrolysis of primary compounds ( real pyrolysis products ) and components that are present as such in the sample and simply evaporate ( free products ). If desired these two types of products may be differentiated using wires with a Curie temperature of 358°C [36], It was demonstrated in separate analyses (not shown here) that most compounds were not generated by pyrolysis but were present as such in the sample and thermally extracted . Compounds 1-8 and 10-17, 27, 37, 38, 54 and 65 were only present in pyrolysis gas... 

Chau et al. [f6] described a hexane extraction procedure to extract tetramethyllead, trimethylethyllead, methyltriethyllead, dimethyldiethyllead and tetraethyllead from marine sediments. The extracted compounds were analysed in their authentic forms by a gas chromatographic-atomic absorption spectrometric system. Other forms of organic and inorganic lead do not interfere. The detection limit was O.Ofmg kg-1 as lead. 

Urine Extract compound from urine using diethyl ether wash with HC1, dry over anhydrous Na2S04, filter evaporate diethyl ether dissolve evaporated residue with diethyl ether HPLC/UV GC/MS NR NR Albro and Moore 1974 Albro et al. 1973... 

Blood Extract compound from blood using heptane3 GC NR NR Lanina et al. 1992... 

Tap water Extract compound with solid-phase extraction technique that uses a membrane impregnated with reverse-phase particles elute with acetonitrile LC Low ppb (pg/L) 82-93 Hagen et al. 1990... 

Preconcentration will only give precise results for quantitative work if the initial extraction technique gives high, or at least known and reproducible, recoveries of the desired compounds from the initial sample. As typically, several cycles are needed, and the solvent containing the extracted compounds must be concentrated to a small volume. This is normally carried out by evaporation under reduced pressure. Volatile compounds may be lost in this procedure. However, for many applications the compounds of interest... 

In the solvent segmenter when it is necessary to avoid precipitation of the extractable compound in the aqueous phase before it reaches the continuous extractor (SS). 

Because of the different experimental conditions, the solvent/amine pair plays a crucial role in the formation of the iiii stereoisomer. Systematic study of the influence of the nature of the base, the reagent/base ratio, and the nature of the solvent (donating power), was performed with the phosphonatocavitands 12a and 12b (Table 1). The procedure is highly solvent dependent the iiii stereoisomer is the major product obtained in toluene, associated with minor amount of iiio isomer. When the reaction is run in acetone other isomers are predominant (ioio, iioo, oooi) and the iiii stereoisomer is not observed. The use of catalytic amount of this amine (0.2 equiv) [64] did not lead to any extractable compounds, and using eight equivalents of amine to trap all the HCl formed, did not change dramatically the yield and the isomer ratio (entries 5 and 6, Table 1). In the presence of triethylamine the iiii and iiio isomers were formed in 28.5% and 7% yields respectively. 

The lab half-life of carbofuran In six soils (each under 4 different levels of moisture and 2-3 different temperatures) was In the range of 5-261 days. After 28 days of aerobic Incubation In two of the six soils, parent carbofuran was the major extractable compound degradation products comprised <5% of the extractable material (65). However, under anaerobic (flooded soil) conditions, the degradation product carbofuran phenol was found to be the principal product and to persist (66). 

Aerobic metaboAsm of extractable compounds such as resin acids via hydroxylation reactions. 

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