Method extraction

The above factors have proven to be justification for the development and implementation of a variety of extraction methods which have been reviewed periodically (1-5). 

As seen in Table 1, extraction methods are divided into two basic groups - liquid/solid and thermal desorption. Both groupings may employ sample preparation techniques such as grinding or cutting to increase surface area and improve extraction efficiency. 

Preparation Grinding and Cutting of Plastics Increase the surface area via ball mills/cutting mills - ambient or cryogenic temperature. Suitable for liquid/solid and thermal desorption methods. (2) 

Dissolution/Reprecipita- tion Dissolution of plastic in suitable solvent or solvent system. Direct analysis or precipitation of polymer with non-solvent. (2), (6) 

Sonication Use of ultrasound energy to agitate the plastic, releasing additives. (7) 

Since oil adheres to metal surfaces to a far greater degree than does water, it is this physical property of adherence that facilitates the recovery of the oil dispersed in the olive paste by percolation. Equipment constructed on the basis of this property is capable of extracting over 70% of the oil present in olive paste. The method is less productive than pressing and centrifuging, but the reward is a top quality oil that many producers rightly consider to be prime (Bianchi, 1999 Di Giovacchino, 2000). 

Holger Stephan, Stefa nie Juran, Bianca Antonioli, Kerstin Cloe and Karsten Cloe 

Molecular recognition, binding and transport of different chemical species represents an aspect of supramolecular chemistry that has relevance to a number of areas that include biochemical processes, analytical techniques, recycling and environmental processes as vell as aspects of catalysis and medicine. Over the years, a large number of both efficient and selective receptors for cations, anions, salts and zwitterions based on different architectures and binding modes have been developed and studied [1-4], 

The state of the art with respect to supramolecular extraction has been summarized in several recent reviews from different perspectives, including in terms of the underlying fundamental chemical processes involved as well as with respect to possible applications in research and industry [7-15], 

It is the intention of this chapter to present an overview of the potential of the extraction technique for characterizing the binding strengths, selectivity, speciation and phase transfer behavior of supramolecular receptors towards selected cations, anions, salts and zwitterions in aqueous-organic, two-phase systems. The role of 

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The calculation of characteristic values causes a high amount of values which contain redundant informations. Due to this the forth partial step will be to reduce this amount of values using extraction methods. This can be realized with statistical methods like cross correlation analysis. 

A much more forgiving yet limited extraction method can be used to isolate phenol species such as eugenol and chavicol. You see farther back in this chapter where one can use dilute NaOH to remove eugenol from sassafras oil Well, why not use it to isolate the damn things for further research. It works like a charm ... 

Adjusting the Analyte s Concentration Analytes present at concentrations too small to give an adequate signal need to be concentrated before analyzing. A side benefit of many of the extraction methods outlined earlier is that they often concentrate the analytes. Volatile organic materials isolated from aqueous samples by a purge and trap, for example, can be concentrated by as much as 1000-fold. 

Caustic Soda. Diaphragm cell caustic is commercially purified by the DH process or the ammonia extraction method offered by PPG and OxyTech (see Fig. 38), essentially involving Hquid—Hquid extraction to reduce the salt and sodium chlorate content (86). Thus 50% caustic comes in contact with ammonia in a countercurrent fashion at 60°C and up to 2500 kPa (25 atm) pressure, the Hquid NH absorbing salt, chlorate, carbonate, water, and some caustic. The overflow from the reactor is stripped of NH, which is then concentrated and returned to the extraction process. The product, about 62% NaOH and devoid of impurities, is stripped free of NH, which is concentrated and recirculated. MetaUic impurities can be reduced to low concentrations by electrolysis employing porous cathodes. The caustic is then freed of Fe, Ni, Pb, and Cu ions, which are deposited on the cathode. 

LPG is recovered from natural gas principally by one of four extraction methods turboexpander, absorption (qv), compression, and adsorption (qv). Selection of the process is dependent on the gas composition and the degree of recovery of ethane and LPG, particularly from large volumes of lean natural gas. 

Analytical and test methods for the characterization of polyethylene and PP are also used for PB, PMP, and polymers of other higher a-olefins. The C-nmr method as well as k and Raman spectroscopic methods are all used to study the chemical stmcture and stereoregularity of polyolefin resins. In industry, polyolefin stereoregularity is usually estimated by the solvent—extraction method similar to that used for isotactic PP. Intrinsic viscosity measurements of dilute solutions in decahn and tetraHn at elevated temperatures can provide the basis for the molecular weight estimation of PB and PMP with the Mark-Houwiok equation, [rj] = KM. The constants K and d for several polyolefins are given in Table 8. 

Violet Leaf. Violet leaf absolute is produced by the usual extraction methods from Viola odorata (var. Victoria). It is grown mainly ia the south of France and Egypt. Although this material is not produced ia large amounts, it is quite valuable ia perfumery for its powerhil green leafy and doral character, an odor that belongs to many doral bouquets. The principal odorant ia violet leaf absolute is 2-/n j -6-i7j -nonadienal [55748-2]. 

The PGM concentrate is attacked with aqua regia to dissolve gold, platinum, and palladium. The more insoluble metals, iridium, rhodium, mthenium, and osmium remain as a residue. Gold is recovered from the aqua regia solution either by reduction to the metallic form with ferrous salts or by solvent-extraction methods. The solution is then treated with ammonium chloride to produce a precipitate of ammonium hexachloroplatinate(IV),... 

One patent (64) describes an extraction method to remove both trichloropropane and tetrachloropropyl ether from the dichi orohydrin solution by the use of carbon tetrachloride as a solvent. In this way the by-products are removed from the aqueous phase iato an organic phase from which they can be separated by distillation and disposed of ia a safe and proper manner. 

Low cholesterol egg products are formed by extraction of cholesterol from the egg. Attempts have been made to extract cholesterol by using hexane or by supercritical CO2 extraction methods (24,25). A whole egg product in which 80% of the cholesterol is removed by a process using beta-cyclodextrin, a starch derivative, added to egg yolks has been introduced. The cyclodextrin binds up to 80% of the cholesterol, the mixture is centrifuged, and the Hquid separated. The cholesterol-reduced yolk is then blended with egg white, pasteurized, and packed in asceptic containers to give a Hquid whole egg product having a shelf Hfe of 60 days under refrigeration (see Eood packaging). 

Application of rotating coiled columns has become attractive for preparative-scale separations of various substances from different samples (natural products, food and environmental samples) due to advantages over traditional liquid-liquid extraction methods and other chromatographic techniques. The studies mainly made during the last fifteen years have shown that using rotating coiled columns is also promising for analytical chemistry, particularly for the extraction, separation and pre-concentration of substances to be determined (analytes) before their on-line or off-line analysis by different determination techniques. 

COMPARISON OF MICROWAVE ASSISTED EXTRACTION METHODS FOR THE DETERMINATION OF PLATINUM GROUP ELEMENTS IN SOIL SAMPLES BY ELECTROTHERMAL ATOMIC ABSORPTION SPECTROMETRY AFTER PHASE SEPARATION-EXTRACTION... 

Prepai ative isolation of nonvolatile and semivolatile organic compounds fractions (hydrophobic weak acids, hydrophobic weak bases, hydrophobic neutrals, humic and fulvic acids) from natural and drinking waters in optimal conditions was systematically investigated by solid-phase extraction method with porous polymer sorbents followed by isolation from general concentrate of antropogenic and/or toxic semivolatile compounds produced in chlorination and ozonation processes. 

The ether extraction method (B) is quicker, especially when several runs are to be made. Mandelic acid is obtained in the same yield by this method. The benzene extraction may be better for small preparations, or when a single run is to be made. 

European Norm EN 120, Wood-based panels. Determination of formaldehyde content. Perforator extraction method, 1995. 

Supercritical fluid extraction (SFE) and Solid Phase Extraction (SPE) are excellent alternatives to traditional extraction methods, with both being used independently for clean-up and/or analyte concentration prior to chromatographic analysis. While SFE has been demonstrated to be an excellent method for extracting organic compounds from solid matrices such as soil and food (36, 37), SPE has been mainly used for diluted liquid samples such as water, biological fluids and samples obtained after-liquid-liquid extraction on solid matrices (38, 39). The coupling of these two techniques (SPE-SFE) turns out to be an interesting method for the quantitative transfer... 

J. R. Dean, Extraction Methods for Environmental Analysis, Jolm Wiley Sons Chichester (1998). 

Although on-line sample preparation cannot be regarded as being traditional multidimensional chromatography, the principles of the latter have been employed in the development of many on-line sample preparation techniques, including supercritical fluid extraction (SFE)-GC, SPME, thermal desorption and other on-line extraction methods. As with multidimensional chromatography, the principle is to obtain a portion of the required selectivity by using an additional separation device prior to the main analytical column. 

Figure 5.3-3 Example of an extraction method for product separation from ionic liquid/catalyst...

Extraction methods, amounts, and lengths of various natural fibers and their physical and chemical properties are given in Tables 2 and 3. 

Table 2 Extraction Methods, Amount, and Length of Various Natural Fibers...

Another way of applying the selective extraction method directly on the initial solution is to produce a solution of low acidity. This can be achieved by using the hydrofluoride method for fluorination and decomposition of raw material. As was discussed in Paragraph 8.2.2, the raw material is fluorinated by molten ammonium hydrofluoride yielding soluble complex fluorides of ammonium and tantalum or niobium. The cake obtained following fluorination is dissolved in water, leading to a solution of low initial acidity that is related for the most part to the partial hydrolysis of complex fluoride compounds. The acidity of the solution is first adjusted to ensure selective tantalum extraction. In the second step, the acidity of the raffinate is increased to provide the necessary conditions for niobium extraction. 

Automation of solvent extraction. Although automatic methods of analysis do not fall within the scope of the present text, it is appropriate to emphasise here that solvent extraction methods offer considerable scope for automation. A fully automated solvent extraction procedure, using APDC, for the determination of... 

An interesting consequence of selective sorption is that conditions for partition chromatography arise which may enhance the normal ion exchange separation factors. This aspect has been utilised by Korkisch34 for separation of inorganic ions by the so-called combined ion exchange-solvent extraction method (CISE). 

Separation techniques may have to be applied if the given sample contains substances which act as interferences (Section 21.10), or, as explained above, if the concentration of the element to be determined in the test solution is too low to give satisfactory absorbance readings. As already indicated (Section 21.10), the separation methods most commonly used in conjunction with flame spectrophotometric methods are solvent extraction (see Chapter 6) and ion exchange (Chapter 7). When a solvent extraction method is used, it may happen that the element to be determined is extracted into an organic solvent, and as discussed above it may be possible to use this solution directly for the flame photometric measurement. 

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