Focused microwave-assisted extraction

With the exception of GC-MIP-AES there are no commercial instruments available for speciation analysis of organometallic species. Recently, a prototype automated speciation analyser (ASA) for practical applications was described [544,545], which consists of a P T system (or focused microwave-assisted extraction), multicapillary GC (MC-GC), MIP and plasma emission detection (PED). MCGC-MIP-PED provides short analysis times ([Pg.676]

Brachet A, Christen P and Veuthey J. 2002. Focused microwave-assisted extraction of cocaine and ben-zoylecgonine from coca leaves. Phytochem Anal 13(3) 162-169. 

Longares, P.A. and Canizares, M.M.P. (2006) Focused microwave-assisted extraction and simultaneous spec-trophotometric determination of vanillin and p-hydroxybenzaldehyde from vanilla fragans. Talanta 69(4), 882-887. 

An effective combination of focused microwave-assisted extraction with solid-phase microextraction (FMAE-SPME) was carried out for the extraction of cocaine... 

Letellier, M. Budzinski, H. Charrier, L. Capes, S. Dorthe, A.M. 1999. Optimization by factorial design of focused microwave assisted extraction of polycyclic aromatic hydrocarbons from marine sediment. Fres. J. Anal. Chem. 364 228-237. 

In addition, microwave power and radiation time of focused microwave-assisted extraction for the quantitative extraction of cocaine and benzoylec-gonine from coca leaves were also optimized using CCD (24). 

Shu, Y. Y., Lai, T. L., Lin, H., Yang, T. C., and Chang, C., Study of factors affecting on the extraction efficiency of polycyclic aromatic hydrocarbons from soils using open-vessel focused microwave-assisted extraction, Chemosphere, 52, 1667-1676, 2003. 

Bieri S, Ilias Y, Bicchi C, Veuthey J-L, Christen P (2006) Focused microwave-assisted extraction combined with solid-phase microextraction and gas chnunatography-mass spectrometry for the selective analysis of cocaine from coca leaves. J Chromatogr A 1112... 

Li, H., Chen, B., Nie, L., and Yao, S. 2004. Solvent effects on focused microwave assisted extraction of polyphenolic acids from Eucommia ulmodies. Phytochemical Analysis, I5(5) 306-312. 

General trends are focused on reduced-solvent extractions or adsorption-based methods — enviromnentaUy friendly solvents for both solid and liquid samples. In recent decades, advanced techniques like supercritical fluid extraction (SFE), ° pressurized liquid extraction (PLE)," microwave-assisted extraction (MAE), ultrasound-assisted extraction, countercurrent continued extraction (www.niroinc.com), solid... 

Weichbrodt et reported on the use of focused open-vessel microwave-assisted extraction (EOV-MAE) for the determination of organochlorine pesticides in high-moisture samples such as fish. The results were comparable to those with closed-vessel microwave-assisted extraction (CV-MAE) and ASE. The main advantage of FOV-MAE is that the use of Hydromatrix is unnecessary as the solvent mixture of ethyl acetate and cyclohexane allows the removal of water from the sample matrix via azeotropic distillation. 

Weichbrodt M, Vetter W, Scholz E, Luckas B, Reinhardt K (1999) Determination of Organochlorine Levels in Antarctic Skua and Penguin Eggs by Application of Combined Focused Open-Vessel Microwave Assisted Extraction, Gel-Permeation Chromatography, Adsorption Chromatography, and GC/ECD. Inter J Environ Anal Chem 73 309... 

Microwave-assisted extractions (MAE) can be performed in open (focused MAE) or closed (pressurized MAE) flasks. This technique is commonly used for extractions from complex and difficult sample matrices, replacing time- and solvent-intensive Soxhlet extractions or hydrodistillations.46 MAE is also widely applied to environmental samples, for example, for extracting polycyclic aromatic hydrocarbons (PAH) from soil, methylmercury from sediments, and trace metals and pesticide residues from plant material47 48 The use of microwave treatment instead of hydrodistillation offers a solvent-free separation technique essential oils are heated and dry-distilled 46... 

This chapter covers techniques for the extraction of semivolatile organics from solid matrices. The focus is on commonly used and commercially available techniques, which include Soxhlet extraction, automated Soxhlet extraction, ultrasonic extraction, supercritical fluid extraction (SFE), accelerated solvent extraction (ASE), and microwave-assisted extraction (MAE). The underlying principles, instrumentation, operational procedures, and selected applications of these techniques are described. In a given application, probably all the methods mentioned above will work, so it often boils down to identifying the most suitable one. Consequently, an effort is made to compare these methodologies. 

Three factors, namely (1) irradiation power as a percentage, (2) irradiation time in seconds and (3) number of cycles, are used to study the focused microwave assisted Soxhlet extraction of olive oil seeds, the response measuring the percentage recovery, which is to be optimised. A central composite design is set up to perform the experiments. The results are as follows, using coded values of the variables ... 

Mermet, J.M. Focused-microwave-assisted reactions atmospheric-pressure acid digestion, on-line pretreatment and acid digestion, volatile species production, and extraction. In Kingston, H.M., Haswell, S.J. (eds.) Microwave-Enhanced Chemistry. Fundamentals, Sample Preparation, and Applications. ACS, Washington, DC (1997)... 

Fig. 5.8. (A) General scheme of a dynamic focused microwave-assisted extractor. (B) Experimental set-up used to integrate microwave-assisted extraction with the subsequent steps of the analytical process. (1) Leaching step CT controller, MO microwave oven, S sample, R condenser, WR water reservoir, TCPP two-channel piston pump, ER extract reservoir, SV switching valve. (2) Clean-up/preconcentration step M methanol, A air, B buffer, PP peristaltic pump, F filter, EL elution loop, MC mini-column, R retention direction, E elution direction, 1V1-1V3 injection valves, W waste. (3) Individual separation-detection step HPIV high-pressure injection valve, AC analytical column, DAD diode array detector, SR solvent reservoirs.

Most studies about the microwave-assisted extraction of PAHs from solid samples have been conducted using closed-vessel systems [12,214,226,236,239-246] and only a few with open-vessel focused microwave devices [57,247-252]. Because open-vessel systems operate at atmospheric pressure, the extraction vessel can be used as a reactor in order to perform on-line purification pretreatments of the total extracts (reagents can be readily added to the medium) [53] or directly introduce the extract into the determination instrument, as in the focused microwave-assisted extractor with on-line fluorescent monitoring of Fig. 5.10, which provides a matrix-independent approach to the extraction of PAHs [61]. 

Focused Microwave assisted Soxhlet Extraction (FMASE) Water is used as the extractant in the application of focused microwaves to enhance the extraction. (9)... 

Luque-Garcia, Focused microwave-assisted Soxhlet extraction, J.L and Luque-Castro, M.D., Anal. Chem., 2001, 73, 5903. 

The focus in Chapters 7 and 8 is on the specific sample preparation approaches available for the extraction of organic compounds from environmental matrices, principally soil and water. Chapter 7 is concerned with the role of Soxhlet, ultrasonic and shake-flask extraction on the removal of organic compounds from solid (soil) matrices. These techniques are contrasted with newer developments in sample preparation for organic compound extraction, namely supercritical fluid extraction, microwave-assisted extraction and pressurized fluid extraction. Chapter 8 is arranged in a similar manner. Initially, details are provided on the use of solvent extraction for organic compounds removal from aqueous samples. This is followed by descriptions of the newer approaches, namely solid-phase extraction and solid-phase microextraction. 

This overview is focused on the on-line coupling of pressurized liquid extraction (PLE), microwave-assisted extraction (MAE), supercritical fluid extraction (SEE) and sonication-assisted extraction (SAE) with liquid and gas chromatography for the analysis of solid agricultural and food samples. In addition, head-space techniques and direct thermal extraction are discussed. 

The improvements in Soxhlet extractions are high-pressure Soxhlet extraction (HPS), automated Soxhlet extraction (Soxhlet HT and Buchi B811) and focused microwave-assisted Soxhlet extraction (Soxwave and FMASE) as shown by Luque de Castro MD and Garcia-Ayuso in 1998. The solvents used for extraction are polar species (dimethyl formamide,... 

New developments in Soxhlet extraction have been applied to the analysis of PAHs in soils and sediments. " Focused Microwave-Assisted Soxhlet Extraction (FMASE) uses focused microwave irradiation to achieve agitation in the sample. The application of microwaves drastically reduces extraction time ( 1 h) and solvent use. Recoveries of PAHs were reported to be 11 to 101 % in the extraction step and no filtering was necessary prior to analysis. 

LLE liquid-liquid extraction SPE solid-phase extraction SPM solid-phase microextraction MAE microwave-assisted extraction SEE supercritical fluid extraction FMASE focused microwave-assisted Soxhlet extraction PSDB polystyrene-divinylbenzene NVPDB A-vinylpyrrolidane-divinylbenzene SPE solid-phase extraction LLE liquid-liquid extraction GPC gel permeation chromatography OPA f -phthalaldehyde reagent TAD thermally assisted desorption FI flow injection... 

Garcia-Ayuso, L. E., Sanchez, M., Fernandez de Alba, A., and Luque de Castro, M. D., Focused microwave-assisted Soxhlet an advantageous tool for sample extraction. Anal. Chem., 70, 2426-2431, 1998. 

Prados-Rosales, R. C., Herrera, M. C., Luque-Garcia, J. L., and Luque de Castro, M. D., Study of the feasibility of focused microwave-assisted Soxhlet extraction of A-methylcarbamates from soil, J. Chromatogr. A, 953, 133-140, 2002. 

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