Accelerated solvent extraction process

A beryUium concentrate is produced from the leach solution by the counter-current solvent extraction process (10). Kerosene [8008-20-6] containing di(2-ethylhexyl)phosphate [298-07-7] is the water-immiscible beryUium extractant. The slow extraction of beryUium at room temperature is accelerated by warming. The raffinate from the solvent extraction contains most of the aluminum and aU of the magnesium contained in the leach solution. 

MAE simply involves placing the sample with the solvent in specialized containers and heating the solvent using microwave energy. MAE is also sometimes called MASE, which can stand for microwave-assisted solvent extraction or microwave-accelerated solvent extraction. In any event, the extraction process is more rapid than Soxhlet extractions, can be run in batches, and reduces solvent consumption. As in the case of sonication, MAE may overcome retention of the analyte by the matrix, but analyte degradation can be a problem at higher temperatures in certain applications. 

Supercritical fluid extraction [153,154], accelerated solvent extraction [68] and subcritical fluid extraction [107,155] have been studied. To reduce the equipment cost and the analysis time in the extraction process and sample preconcentration, a solid-phase microextraction method was proposed by Pawliszyn and coworkers [156-158]. 

Accelerated solvent extraction (ASE) is becoming more popular because of its rapidity. This however is offset by sequential sample processing. Samples are placed in a stainless steel vessel and subj ected to solvent at elevated pressure and temperature. The pH of the extraction can be modified to assist in extracting acidic or basic compounds. 

Pressurized solvent extraction (PSE), also called pressurized fluid extraction (PEE), accelerated solvent extraction (ASE ), pressurized liquid extraction (PEE), or enhanced solvent extraction (ESE), is a solid-liquid extraction that has been developed as an alternative to conventional extractions such as Soxhlet, maceration, percolation, or reflux. It uses organic solvents at high pressure and temperature to increase the efficiency of the extraction process. Increased temperature decreases the viscosity of the liquid solvent, enhances its diffusivity, and accelerates the extraction kinetics. High pressure keeps the solvent in its liquid state and thus facilitates its penetration into the matrix, resulting in increase extraction speed [30]. 

Accelerated solvent extraction as implemented in commercial equipment is basically discrete in nature, so it is rarely coupled to other operations of the analytical process. In fact, only in two reported applications was the static mode coupled on-line to other operations such as chromatographic separation, preconcentration and detection. Both used custom extractors as the compact design of the commercial models precluded their adaptation. 

A recent advance is accelerated solvent extraction (ASE), a method that uses high temperature and pressure to push an organic solvent through a solid material and to collect the eluent in a vial (Fig. 9.2). The instrument, made by Dionex, is automated and may run 30 samples at once. The instrument can process one sample every 15 min with extraction efficiencies equal to that produced by Soxhlet extraction in 12 h (Dionex, Product Literature, Appendix). The extraction does not use supercritical fluids but consists of using elevated... 

A sensitive HPLC multimethod was developed by BreithaupT for the determination of the carotenoid food additives (CFA) norbixin, bixin, capsanthin, lutein, canthaxanthin, b-apo-80-carotenal, b-apo-80-carotenoic acid ethyl ester, b-carotene, and lycopene in processed food using an RP C30 column. For unequivocal identification, the mass spectra of all analytes were recorded using LC-(APcl) MS. For extraction, a manual process as well as accelerated solvent extraction (ASE) was applied. Important ASE parameters were optimized. ASE was used for the first time to extract CEA from various food matrices. Average recoveries for all analytes ranged from 88.7% to 103.3% (manual extraction) and from 91.0% to 99.6% (ASE), with the exception of norbixin using ASE (67.4%). Limits of quantitation (LOQ) ranged from 0.53 to 0.79 mg/L. The presented ASE method can be used to monitor both, forbidden application of CFA or the compliance of food with legal limits. 

Quality assurance in the paint industry demands not only quality control of final products, but also a careful control of raw materials and manufacturing processes. Paint manufacturers require simple and fast analytical procedures for online control. It is important to obtain measurements directly from whole samples, without any prior treatment, and the incorporation of sample preparation techniques, such as supercritical fluid extraction or accelerated solvent extraction, which facilitate the separation of paint components prior to their analysis. 

For many years, the traditional sample preparation methods, such as the Soxhlet extraction, were applied. Most of these methods have been used for more than 100 years, and they mostly require large amounts of organic solvents. These methods were tested during those times, and the analysts were familiar with the processes and protocols required. However, the trends in recent years are automation, short extraction times, and reduced organic solvent consumption. Modern approaches in solid sample preparation include microwave-assisted solvent extraction (MASE), pressurized liquid extraction, accelerated solvent extraction (ASE), matrix solid-phase dispersion (MSPD), automated Soxhlet extraction, supercritical fluid extraction (SEE), gas-phase extraction, etc. 

In this context, studies about the development of relevant analytical methods allowing the detection of pesticide residues in VOO are usually focused on an optimization of the various steps of the analysis process, namely extraction, clean-up, identification, and quantitation of pesticide content. The common extraction methods are Soxhlet extraction, microwave-assisted extraction (MAE), supercritical fluid extraction (SEE), and accelerated solvent extraction (ASE). Cleanup methods include SPE, matrix solid-phase dispersion (MSPD), and gel permeation chromatography (GPC). 

Accelerated solvent extraction (ASE) is a relatively recent advance in sample preparation for trace environmental analysis. This techiuque uses conventional solvents at elevated pressures and temperatures to extract solid samples quickly. The process takes advantage of the increased analyte solubilities at temperatures well above the boiling points of common solvents. Under these conditions, the kinetic processes for the desorption of analytes from the matrix are accelerated. Currently a commercial unit is available in which automated extractions can be carried out on 24 samples sequentially (Richter et al., 1995, 1996). This technique offers some significant advantages over SEE and MAP. SEE uses supercritical CO2, which is a nonpolar fluid, whereas MAP requires the presence of a polar solvent that couples with microwave to promote heating. By comparison, ASE uses the same solvent as traditional Soxhlet extractions, which means a (firect transfer of methodology is feasible without any of the restrictions or limitations of the two other methods. Method development time is therefore shortened. 

Erdogan S, Erdemoglu S (2011) Evaluation of polyphenol contents in differently processed apricots using accelerated solvent extraction followed by high-performance liquid chromatography diode array detector, hit J Food Sci Nutr 62(7) 729-739... 

Particulate matter, obtained from the filtration process, can be analyzed with the same analytical methods normally used for sediment samples. Solvents used in the filter extraction are generally the same as those previously described for liquid-liquid extraction (i.e., -hexane [152], toluene [31], and pentane/mefhylene chloride (2 1) [85]). However, water-miscible solvents can also be used such as acetone, ethyl acetate and methanol (n-heptane/acetone (1 1) [67], hexane/acetone (3 2) [10], dichloromethane/methanol (2 1) [46], and dichloromethane/methanol (2 1) [135]). The extraction process is carried out in a Soxhlet extractor or, more simply, in an ultrasonic bath— this improves the exchange process between the particle surface and the bulk of the organic solution. Pressurized liquid extractions (accelerate solvent extraction) can be used for a more efficient extraction, above all in terms of extraction times [10,67]. 

A recent study published in the Chinese Journal of Instrumental Analysis, Fenxi Ceshi Xuebao, showed a detection limit of 500 ng of Sulfur Mustard (HD) by using accelerated solvent extraction-gas chromatography (ASE-GC) coupled with a flame photometric detector (EPD) in the sulfur mode, in soil. In this case, the study showed evidence that ASE results in better recoveries and sensitivity than liquid solid extraction (LSE) [50]. In 1996, a paper was published on a method for the analysis of Lewisite through derivatization of the compound before introduction into a gas chromatograph. In order to simplify the derivatization process, a tube packed with absorbent was used for collection of airborne vapors. If a positive response occurs when screening analytes using a GC coupled with an FPD, then the same sample can be analysed using a GC equipped with an AED for confirmation based on the elemental response to arsenic (in the case of Lewisite) and sulfur (in the case of Sulfur Mustard) within the appropriate GC retention time window [54]. 

Applications As the basic process of electron transfer at an electrode is a fundamental electrochemical principle, polarography can widely be applied. Polarography can be used to determine electroreductible substances such as monomers, organic peroxides, accelerators and antioxidants in solvent extracts of polymers. Residual amounts of monomers remain in manufactured batches of (co)polymers. For food-packaging applications, it is necessary to ensure that the content of such monomers is below regulated level. Polarography has been used for a variety of monomers (styrene, a-methylstyrene, acrylic acid, acrylamide, acrylonitrile, methylmethacrylate) in... 

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