Extraction methods overview

Overview of Selected Soil Pore Water Extraction Methods for the Determination of Potentially Toxic Elements in Contaminated Soils Operational and Technical Aspects... 

Overview of Selected Soil Pore Water Extraction Methods... 

Table 7 Overview of traditional and more recent extraction methods...

Figure 5.20 Overview of the sequential extraction method for metals, as applied to the analysis of soils and sediments.

Table 7.2. Overview of fumigation extraction methods for microbiai phosphorus determination. 

Jacquel and co-workers [5] gave an overview of the various PHA extraction methods used, along with the respective purity and recovery, from 1978 to 2006. Furthermore, Roller and co-workers [3], and Kunasundari and Sudesh [27] gave a thorough review up to 2010. In this section, the subsequent updates on PHA recovery are discussed. Table 6.1 shows a summary of the recovery methods with respect to the influencing factors in each study reported from 2011 to 2015. 

Other extraction methods like (Ultra-Turrax) blending, ultrasonic, and solvent extractions are available. Most of these techniques show good recoveries for specific matrices, and after optimization of the extraction conditions. Microwave assisted extraction is another promising technique. Good recoveries for PCBs have been obtained. The extraction time is short, and samples can be extracted simultaneously. An overview of advantages and disadvantages of the various extraction techniques is given in Table 2. 

The use of essential oils is increasing because of the increase in the number of their apphcations and in the framework of natural and environmentally friendly materials. Many times the analysis of their components is quite complex due to the high number and the diversity of compounds in their composition. In this entry a general overview of the extraction methods is given by comparing conventional hquid-liquid and sohd-hquid methods with new alternative ones, such as supercritical fluid extraction and microwave-assisted extraction. Gas chromatography methods and examples are treated and important issues such as detection systems, modem hbraries for compounds identification, as well as multidimensional or hyphenated techniques are discussed. The use of these modem techniques and methods has improved resolution and sensitivity in essential oils determination and could open the possibihty of future work in this area of chromatography. 

For overviews on extraction methods see the following general references ... 

The analysis of volatiles is generally accomplished by an extraction step, followed by concentration, chromatographic separation, and subsequent detection. Well-established methods of analysis include solvent extraction, static and dynamic headspace sampling, steam distillation with continuous solvent extraction, and supercritical fluid extraction. An overview of sample preparation methods is provided by Teranishi (2). The chromatographic profile will vary depending upon the method of sample preparation employed, and it is not uncommon to produce artifacts during this step (3,4). Thermally labile compounds may decompose in the heated zones of instruments to produce a chromatographic profile that is not truly representative of the sample. 

An overview is presented of plutonium process chemistry at Rocky Flats and of research in progress to improve plutonium processing operations or to develop new processes. Both pyrochemical and aqueous methods are used to process plutonium metal scrap, oxide, and other residues. The pyrochemical processes currently in production include electrorefining, fluorination, hydriding, molten salt extraction, calcination, and reduction operations. Aqueous processing and waste treatment methods involve nitric acid dissolution, ion exchange, solvent extraction, and precipitation techniques. 

We will give here a short overview of the most common XRPD techniques used to study the microstructure of materials, starting from the most used and simple Scherrer method to the quite complex Warren-Averbach method, which is able to extract all the information available on sample microstructure and defects. 

Separation and detection methods A survey on determination of tin species in environmental samples has been published by Leroy et al. (1998). A more detailed overview of GS-MS methodology has been published by Morabito et al. 1995) and on sample preparation using supercritical fluid extraction has been described by Bayona (1995)- The techniques are now under control, so that routine procedures are available at a relatively low cost (Leroy et al. 1998). 

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