Extraction methods applications

For the analysis of solid tissue samples such as muscle, kidney, or liver, a representative liquid sample first has to be obtained. Fluids can be simply collected by the fluid expression technique (Section 5.2.4). To improve detection limits for certain compounds and provide an alternative method for samples where the fluid cannot be obtained by expression alone. Stead et al. described a solvent extraction method applicable for the generic recovery of antimicrobial compounds from a wide variety of matrices. A comparison of the fluid expression and solvent extraction techniques in combination with the... 

Soils, sediments, and biosolids are complex matrices and extraction of organic contaminants and their TPs has been more challenging than in aqueous media since co-extracted material present in these samples can severely reduce the efficiency of extraction. Therefore, it is essential to develop effective methods for extraction and purification. Due to the thermolabile properties and polar nature of many TPs, traditional extraction methods such as Soxhlet are not appropriate and other techniques such as pressurized Hquid extraction (PLE), microwave-assisted extraction (MAE), microwave-assisted Soxhlet extraction (MASE), and ultrasonic solvent extraction are more suitable. A summary of extraction methods applicable to the determination of pesticide TPs in soHd matrices (soil) is presented in Table 4. 

Table 2 A sequential extraction scheme for trace metal speciation in sediments. The first three steps relate to the standardized sequential extraction method applicable to BCR CRM 601 ...

A variety of methods have been developed by mathematicians and computer scientists to address this task, which has become known as data mining (see Chapter 9, Section 9.8). Fayyad defined and described the term data mining as the nontrivial extraction of impHcit, previously unknown and potentially useful information from data, or the search for relationships and global patterns that exist in databases [16]. In order to extract information from huge quantities of data and to gain knowledge from this information, the analysis and exploration have to be performed by automatic or semi-automatic methods. Methods applicable for data analysis are presented in Chapter 9. 

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. 

Several extraction methods for water samples are applicable, such as solvent extraction, SPE using a cartridge and disk and solid-phase microextraction (SPME). 

In this section we will focus on the methods applicable to the study of interfacial extraction kinetics which were developed in our group. 

Conventional methods of polymer extraction use large quantities of solvents as in shake-flask extraction or a Soxhlet extraction apparatus. For all classical extraction methods, solvent selectivity, in general, is low, i.e. solvents with high capacity tend to have low selectivity. In reflux extractions, which are still quite popular in polymer applications, the polymer is refluxed with a hot solvent, which disperses it to provide a solvent phase containing additives. In these conditions solvents are at their atmospheric boiling point. These methods are lengthy and labour intensive. Fractional extraction is based on solvents with increasing solvent power (cf. also [81]). 

Applications The in-vial LSE of additives is used in several laboratories (e.g. GE, DSM Plant Laboratories) but other extraction methods are more popular. Use may be envisaged in particular for specific routine applications in plant services at low cost. Desrosiers [23] has reported that up to 3 g of either ground or thin disk strips may be put completely into solution at 140 °C and an extraction period of 15min. Ashton [111] used... 

SFE instrument development has greatly been stimulated by the desire of the Environmental Protection Agency (EPA) to replace many of their traditional liquid-solvent extraction methods by SFE with carbon dioxide. In the regulatory environment, EPA and FDA approved SFE and SFC applications are now becoming available. Yet, further development requires interlaboratory validation of methods. Several reviews describe analytical SFE applied to polymer additives [89,92,324]. 

The principles behind MAP liquid-phase and gas-phase extractions are fundamentally similar and rely on the use of microwaves to selectively apply energy to a matrix rather than to the environment surrounding it. MAP gas-phase extractions (MAP-HS) give better sensitivity than the conventional static headspace extraction method. MAP-HS may also be applied in dynamic applications. This allows the application of a prolonged, low-power irradiation, or of a multi-pulse irradiation of the sample, thus providing a means to extract all of the volatile analytes from the matrix [477]. 

Isolation may occur by liquid-solid interaction (extraction, dissolution) or heat (thermal, pyrolytic, laser). Extraction methods easily handle qualitative screening for low- to medium-MW compounds fail for high-MW components or polymer-bound functionalities and are less reliable quantitatively (analyte dependent). When applicable, dissolution methods suffer from sensitivity, because of the dilution effect on account of the polymer. In-polymer analysis performs well for qualitative screening, but is as yet not strongly performing for quantitative analysis, except for some specific questions. 

Based on the heat-induced AR principle, DNA/RNA extraction from FFPE tissues can be successfully achieved by a simple heating protocol that allows satisfactory application of molecular analysis using FFPE tissue samples housed in pathology laboratories worldwide. By a combination of improved extraction methods with various innovative techniques of molecular biology, more reliable results of molecular profiling for archival tissue are anticipated. 

Marin A, Lopez-Gonzalvez A, Barbas C. Development and validation of extraction methods for determination of zinc and arsenic speciation in soils using focused ultrasound application to heavy metal study in mud and soils. Anal. Chim. Acta 2001 442 305-318. 

The popularity of this extraction method ebbs and flows as the years go by. SFE is typically used to extract nonpolar to moderately polar analytes from solid samples, especially in the environmental, food safety, and polymer sciences. The sample is placed in a special vessel and a supercritical gas such as CO2 is passed through the sample. The extracted analyte is then collected in solvent or on a sorbent. The advantages of this technique include better diffusivity and low viscosity of supercritical fluids, which allow more selective extractions. One recent application of SFE is the extraction of pesticide residues from honey [27]. In this research, liquid-liquid extraction with hexane/acetone was termed the conventional method. Honey was lyophilized and then mixed with acetone and acetonitrile in the SFE cell. Parameters such as temperature, pressure, and extraction time were optimized. The researchers found that SFE resulted in better precision (less than 6% RSD), less solvent consumption, less sample handling, and a faster extraction than the liquid-liquid method [27]. 

Nowadays, SPE has been shown to be a very powerful and robust alternative to the traditional extraction methods stated above [29,30], It offers the advantages of very low solvent consumption, speed, and ease of handling, and combines the concentration and (partial) clean-up into one on-line step. Various types of commercially available stationary phases enable the application of distinct separation mechanisms, thereby increasing the selectivity of the adsorbent to the analytes. 

The biological applications of NMR include the study of the structure of macromolecules such as proteins and nucleic acids and the study of membranes, and enzymic reactions. Newer methods and instruments have overcome, to a large extent, the technical difficulties encountered with aqueous samples and the analysis of body fluids is possible, permitting the determination of both the content and concentration of many metabolites in urine and plasma. NMR is not a very sensitive technique and it is often necessary to concentrate the sample either by freeze drying and dissolving in a smaller volume cm- by solid phase extraction methods. 

A recent and extremely important development lies in the application of the technique of liquid extraction to metallurgical processes. The successful development of methods for the purification of uranium fuel and for the recovery of spent fuel elements in the nuclear power industry by extraction methods, mainly based on packed, including pulsed, columns as discussed in Section 13.5 has led to their application to other metallurgical processes. Of these, the recovery of copper from acid leach liquors and subsequent electro-winning from these liquors is the most extensive, although further applications to nickel and other metals are being developed. In many of these processes, some form of chemical complex is formed between the solute and the solvent so that the kinetics of the process become important. The extraction operation may be either a physical operation, as discussed previously, or a chemical operation. Chemical operations have been classified by Hanson(1) as follows ... 

Several sampling procedures are applicable to volatile compounds but method application often depends on the compound(s) to be sampled (Dean, 2003). Part of the issue of sampling volatile compounds arises because some volatile substances sublime rather than boil, whereas other volatile substances emit significant quantities of vapor well below their boiling point. For sampling volatile hydrocarbons in the field, two procedures are generally recommended zero headspace and solvent extraction. However, these two procedures do not necessarily give equivalent results. 

Metal dithiophosphate complexes are involved in a wide variety of analytical methods for metals. Diethyldithiophosphoric acid reportedly 13-1 is) fonns complexes with thirty-five elements, mainly metals, in various oxidation states which are useful for solvent extraction. No attempt is made here to detail all the applications to solvent extraction methods which have been described since these ate summarized in the texts listed. Dithiophosphoric... 

The specimen will be the basis for the analytic analysis. Is it RNA or DNA What is the origin of the tissue Amniocentesis Was it a spontaneous product of conception Were anatomic pathology slides or tissue blocks prepared Are cell lines involved Are these primary or immortalized Was a chorionic villus sampling procedure done Is the sample properly collected peripheral blood The answers to each of these questions should be noted, and considered part of the validation of a useful nucleic acid extraction method. A molecular diagnostics laboratory should adhere to the highest standards in providing services, and prior validation of applicable nucleic acid extraction procedures is a must to ensure high-quality service. 

As its name suggests, supercritical fluid extraction (SEE) relies on the solubilizing properties of supercritical fluids. The lower viscosities and higher diffusion rates of supercritical fluids, when compared with those of liquids, make them ideal for the extraction of diffusion-controlled matrices, such as plant tissues. Advantages of the method are lower solvent consumption, controllable selectivity, and less thermal or chemical degradation than methods such as Soxhlet extraction. Numerous applications in the extraction of natural products have been reported, with supercritical carbon dioxide being the most widely used extraction solvent. However, to allow for the extraction of polar compounds such as flavonoids, polar solvents (like methanol) have to be added as modifiers. There is consequently a substantial reduction in selectivity. This explains why there are relatively few applications to polyphenols in the literature. Even with pressures of up to 689 bar and 20% modifier (usually methanol) in the extraction fluid, yields of polyphenolic compounds remain low, as shown for marigold Calendula officinalis, Asteraceae) and chamomile Matricaria recutita, Asteraceae). " ... 

Extraction and Thermal-Optical Carbon Analysis Methods Application to Diesel Vehicle Exhaust Aerosol, Environ. Sci. Tech-noi, 18, 231-234 (1984). 

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