Extraction exhaustive

Raw NBR containing 1.5% of the built-in antioxidant retained 92% of its original resistance to oxidation after exhaustive extraction with methanol. NBR containing a conventional aromatic amine antioxidant (octylated diphenyl amine) retained only 4% of its original oxidative stabiUty after similar extraction. 

N-(4 Methoxyphenyl)-N-benzoyl-3-chloro-3-chloroantranlllc acid (4) 2 To ice cooled NaoEt (Irom 0 11 g Na and 10 mL ElOH) was added in rapid succession meltiyl 2 chloro 6 hydroxybenzoate 2 (0 86 g 4 7 mmol) and N (4 methoxyphenyl)benzimidyl chloride 1 (t 14 g 4 7 mmol) in EI2O (30 mL) The mixture was stirred vigorously and allowed to stand at rt tor 48 h The oily solid obtained alter evaporation was heated to 210 215°C lor 70 min under N2 The product was diluted with water (5 4 mL) ElOH (10 8 mL) and treated with 1 M NaOEt (5 4 mL) The mixture was relluxed lor 90 mm the solvent evaporated and the aqueous solution acldilied The dark oil was heated with NaOH (7 5 g) m EtOH (22 mL) Alter removal ol benzoic acid by exhaustive extraction with water the product was recrystallized Irom EtOH to give 0 36 g ol 4 (27 7%), mp 139 5 140 5°C... 

On the other hand, quantitative extraction requires complete and exhaustive extraction and no material can be lost. To assure complete extraction when a food is analyzed for the first time in a laboratory, it is useful to carry out two or three extractions, pool the solvents, and keep separate the next extracts to verify the presence of carotenoids. Usually four to six extractions are enough to remove the carotenoids completely from a sample. The extraction can be carried out in a blender, vortex, or with a mortar and pestle. Accelerated solvent extraction (ASE), an important extraction technique in residue analysis, currently attracts interest due to its short duration, low level of solvent use, and high extraction yield. The average recoveries for all carotenoids with the exception of norbixin ranged from 88.7 to 103.3% using manual extraction and from 91.0 to 99.6% by ASE (70 bar and temperature of 40°C) both extractions were carried out with a mixture of MeOH, EtOAc, and petroleum ether (1 1 1). ... 

The fundamental issue is to describe how much of the residue can be characterized accurately and whether an accounting of the applied mass of pesticide can be maintained throughout the course of the experiment. A series of environmental fate studies is required for pesticide registration in order to characterize the degradation pathways and formation and decline patterns of each major degradate. These studies are typically conducted in the laboratory under controlled conditions, applying radiolabeled pesticides to evaluate the extraction efficiency of various procedures. When standard extraction methods fail to release a significant amount of the applied radioactivity, more efficient and exhaustive extraction procedures are tried in a stepwise fashion... 

Because the protein analyte is endogenous to the plant, it can be difficult to demonstrate the efficiency of the extraction procedure. Ideally, an alternative detection method (e.g., Western blotting) is used for comparison with the immunoassay results. Another approach to addressing extraction efficiency is to demonstrate the recovery of each type of protein analyte from each type of food fraction by exhaustive extraction, i.e., repeatedly extracting the sample until no more of the protein is detected. " ... 

Soxhlet extraction is well established, and generally exhaustively extracts all additives. The selection of extraction solvent can make large differences to the extraction time. The generally long extraction times followed by concentration steps may determine losses of volatile or thermally labile components. Because this form of extraction is one of the oldest and still widely used in industry, it is the standard to which many of the newer extraction technologies (which are likely to determine future applications) are referred. However, it should be realised that extraction mechanisms may be different, and thus comparisons are sometimes irrelevant. 

Applications Dissolution/reprecipitation is claimed to be the most widespread approach to polymer/additive analysis [603], but recent round-robins cast some doubt on this statement. Dissolution appears to be practised much less than LSEs. However, in cases where exhaustive extraction is difficult, e.g. for polyolefins containing high-MW (polymeric) additives, a dissolution/precipitation method is preferred. 

As for sample preparation, SPE-GC has become more popular than NPLC-GC. Aqueous samples are not compatible with NPLC-GC, while RPLC-GC has never become a success. SPE-GC-(tandem)MS and SPE-GC-AED systems have demonstrated excellent performance. SPME is an equilibrium technique while SPE affords exhaustive extraction of the analytes. Laser desorption injection in LD-GC-MS can uniquely provide an additional dimension of spatial information for 2D surface chemical mapping [221]. 

The recovery of DDT by this method was 93 to 96% (5), as confirmed by exhaustively extracting a drained sample with benzene and analyzing the extract for DDT. Two samples per operator could be prepared for drying in 1 day however, 3 days elapse between the start and finish of the processing when done in this way. 

In a typical extraction, 50 jiL of plasma was treated with 25 /./I. of internal standard solution and then diluted with 200 /iL of 3% ammonium hydroxide. The C18 /./-SPE tips were conditioned with 150 /iL of methanol and then 300 /./I. of 3% ammonium hydroxide. The sample was exhaustively extracted by aspirating and dispensing the plasma samples seven times from the dilution tube. For the wash, 90 /./I. of 3% ammonium hydroxide followed by 100 /./I. of methanokwater (20 80 v/v) was used. Elution was achieved with 50 /./I. of methanokwater (90 10 v/v). After evaporation of the collected eluate in the 96-well block, the residues were reconstituted in 200 fjL of mobile phase A B... 

Although some researchers have chosen to extract aqueous wastewater matrices with traditional methods, such as liquid-liquid extraction [5,22], other researchers have used solid-phase extraction (SPE) to exhaustively extract FMs from these matrices [2,8,11,14,19,20]. Simonich et al. [2,11] used C18 Baker-bond Speedisks to extract 16 FMs, with a wide range of polarities, from 0.5-L influent and primary effluent and 1.0-L final effluent samples. Verbruggen et al. 

Verbruggen et al. [20] PCMs (AHTN and HHCB) Wastewater effluent The Netherlands - Biomimetic and exhaustive extraction - C18 Empore disks - GC-MS - Recovery >95% detection limit=0.1 ng/L... 

The aqueous hydrazide solution is evaporated from a tared 2000 ml flask on an efficient rotary evaporator, using a bath temperature of 40° and an ice-cooled condenser the 3000 ml siphon flask assembly is used as storage for the vacuum feed. The weight of the crude hydrazide so obtained is determined, it is dissolved in about 170 ml 1 N tartaric acid, the aqueous solution washed with three 30 ml portions ether, made alkaline with 190 ml 1 N ammonium hydroxide, and exhaustively extracted with successive portions of chloroform, the first two portions being 100 ml each, the following 50 ml. 

Potassium cyanate (40 g.) and ammonium sulphate (40 g.) are dissolved in 500 c.c. of water in a porcelain basin, and the solution is evaporated to dryness on the water bath. The residue is exhaustively extracted in a round-bottomed flask with boiling absolute alcohol, and the alcoholic solution is concentrated until, on... 

Flavonol truxinix esters with possible myorelaxant activity were determined in Pseudotsuga menziesii using various TLC stationary and mobile phases. Because of chemotaxonomical interest the same investigations were carried out on 34 species from the family of Pinaceae. Dried and pulverized needles were exhaustively extracted with chloroform followed with methanol. The chloroform fraction was evaporated to 5 ml and... 

Chemisorption involving covalent bonds as well as bound residue formation is also excluded, which is defined as any organic carbon remaining after exhaustive extraction that results from degradation of parent molecules. 

In a Friedel-Crafts reaction, the chloride was treated with dimethyl-aniline in the presence of aluminum chloride. Nitrobenzene was used as solvent. After exhaustive extraction, the nitrogen content was equimolar to the former chloride content. No NaHCOj was neutralized by the reaction product the other neutralization values decreased correspondingly. 

The presence of high-molecular weight p-sulfur with chain structure seemed improbable since the sulfur was not extractable with boiling toluene. The p-sulfur is known to convert to the soluble ring structure (Sg) rather rapidly at 115°. Wibaut (119) thought the formation of a carbon-sulfur complex similar to the surface oxide formed with oxygen very likely. He was not able, however, to analyze definite surface groups. Hofmann and Nobbe (123) established that the sulfur content was dependent on the specific surface area. Enoksson and Wetterholm (124) confirmed by X-ray diffraction that no crystalline sulfur was present in exhaustively extracted charcoal with 13% sulfur content. 

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