Soxhlet extraction microwave-assisted

Extraction of solid samples Homogenization extractions Sonication extractions Microwave assisted extractions Soxhlet extractions Accelerated solvent extractions Supercritical fluid extractions Extraction of liquid samples Liquid-liquid extractions Solid phase extractions (SPE)... 

Fast Soxhlet extractions 71 3.4.5 Microwave-assisted extractions. 104... 

S, Soxhlet S , Soxtec R, reflux SF, shake-flask US, ultrasonics SFE, supercritical fluid extraction MAE, microwave-assisted extraction PFE, pressurised fluid extraction (ASE , ESE ) D/P, dissolution/precipitation. 

Zuloaga O, Etxebarria N, Fernandez LA, Madariaga J. Comparison of accelerated solvent extraction with microwave-assisted extraction and Soxhlet for the extraction of chlorinated biphenyls in soil samples. Trends Anal. Chem. 1998 17 642-647. 

Heise and Litz [26] investigated the extraction behaviour of surfactants (LAS, NPEO and cationics) from sand comparing Soxhlet extraction, accelerated solvent extraction (ASE) and microwave-assisted extraction. Fractionation of the three surfactant types anionic, non-ionic and cationic, was accomplished by column chromatography with aluminium oxide. Soxhlet extraction and ASE of spiked sand with methanol—stored during 7 days prior to extraction—gave similar recoveries for both LAS and NPEO with values between 88 and 116%. Less efficient extraction was achieved by microwave extraction (79% for NPEO). 

Supercritical fluid extraction (SFE), microwave-assisted extraction (MAE) and Soxhlet extraction under various experimental conditions were applied for spiked poly(vinyl) chloride samples. Extracted dyes were separated in an ODS column (250 X 4.6 mm i.d. particle size 5 jum) using methanol as the mobile phase. Dyes are well separated by this method as demonstrated in Fig. 3.59. The optimal parameters of the extraction methods are compiled in Table 3.23. Recoveries depended on both the type of extraction method and the chemical structure of the dye. It was found that the highest recovery can be obtained by MAE and the extraction efficacy was the lowest for Solvent red 24 [129],... 

Microwave-assisted extraction (MAE) is a recent extraction technique, which combines microwave and traditional solvent extraction. The MAE approach have many advantages, such as shorter time, less solvent, higher extraction rate and better products with lower cost. Soxhlet... 

Lopez-Avila et al. [107] showed that microwave-assisted extraction of pesticides and polycyclic aromatic hydrocarbons from soil is a viable alternative to Soxhlet extraction and needs a smaller sample volume and extraction time [108,109]. These techniques have also been compared in the case of chlorophenols. Lopez-Avila et al. compared microwave-assisted extraction with electron capture gas chromatography to ELISA for the determination of polychlorinated biphenyls in soils. Both techniques are applicable to field screening and monitoring applications. Microwave-assisted extraction [111, 112] and solid-phase microextraction [113] have been applied to the extraction of pesticides from soil. It was observed by these and other workers [114] that the selectivity of microwave-assisted extraction is highly dependent on the soil composition. 

Various other extraction techniques have been used to recover hydrocarbons from soil including microwave-assisted extraction [19] and supercritical fluid extraction coupled with on-line infrared spectroscopy detection [20,21], The on-line SFA infrared procedure produced results similar to those obtained by Soxhlet extraction. 

Solid-phase microextraction [320-322], microwave-assisted extraction [321, 323], accelerated solvent extraction and Soxhlet extraction have been discussed [324,325]. 

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. 

Although the traditional Soxhlet and solvent extraction techniques are widely accepted, they have inherent limitations and problems. Thus, Soxhlet extraction requires 12-24 h in most cases and uses high volumes of organic solvents (hundreds of millilitres). In contrast to conventional methods, microwave-assisted extraction can reduce the extraction time to less than 30 min and solvent consumption to under 50 ml [12]. Moreover, the recoveries obtained with microwave-assisted extraction are comparable with those provided by alternative extraction methods [7]. 

The increasing risks to human health posed by the widespread use of pesticides in our environment is well established [212,213]. Thus, the determination of pesticides in water, plants, soil, sediments, foodstuff, etc., is of major concern today [214,215]. Microwave-assisted extraction provides an efficient, reproducible alternative to classical methods based on Soxhlet extraction or sonication for the extraction of pesticides from environmental samples. 

Microwave-assisted extraction (MAE) has become a major choice for the extraction of PCBs from solid matrices. In fact, this technique has been used to extract PCBs from a wide range of samples including soil, sediments and animal tissues [254-257], as well as certified reference materials (CRMs) [258]. Normally, the extractant used is the same as that employed with PAHs, viz. a 1 1 hexane-acetone mixture [246] however, organized media [256] have also provided results similar to those obtained with conventional methodologies such as Soxhlet extraction [259]. For example, the results for a range of Aroclors (1254, 1260, 1016 and 1248) were quite consistent with their certified values. The microwave-assisted extraction of PCB Aroclors 1248, 1254 and 1260 followed... 

Traditional methods of extraction, such as Soxhlet, have been replaced by modern techniques as supercritical fluid extraction (SFE), microwave-assisted extraction (MAE), ultrasonic extraction, and accelerated solvent extraction (ASE) during recent years. The application of specific methods to these kinds of samples has permitted the development of a great number of other extraction methods. In the following list, a brief description is given ... 

A study was carried out for LEE by the Soxhlet method and microwave-assisted extraction for the determination of the priority phenols in soil samples. Recoveries varied from 67 to 97% with RSD between 8 and 14% for LEE, and >70% for the MAP, except for nitrophenols that underwent degradation when the latter method was applied. LOD was from 20 ngg for 2,4-dimethylphenol to 100 ngg for pentachlorophenol. The best detection method for EC was atmospheric pressnre chemical ionization MS (APCI-MS). The most abnndant ions obtained by this detection method were [M — H] for the lowly chlorinated phenols and [M — H — HCl] for tri-, tetra- and pentachlorophenols . 

Figure 7.13 Results obtained for the atmospheric microwave-assisted extraction of various polycyclic aromatic hydrocarbons from contaminated soil, and comparison with those obtained from Soxhlet extraction , Soxhlet , aMAE 1, naphthalene 2, acenaphthylene 3, acenaphthene 4, fluorene 5, phenanthene 6, anthracene 7, fluoranthene 8, pyrene 9, benz[a]anthracene 10, chrysene 11, benzo[fr, ]fluoranthene 12, benzo[a]pyrene 13, indeno[l,2,3-cd]pyrene 14, benzo[gfe ]pyrene [1] (cf. DQ 7.10).

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. 

Soxhlet extraction remains the most popular means of extracting CPs from solid samples [11,18, 19, 23, 25, 28]. This classical technique is robust, easy to use, and inexpensive and has been applied successfully to the analysis of other organohalo-genated compounds. Drawbacks to the technique are lengthy extraction times (typically greater than 6 h) and the use of large volumes of solvents. Newer techniques like pressurized fluid extraction (PLE, or accelerated solvent extraction (ASE)) and microwave assisted extraction (MAE) have been shown to mitigate these two factors. 

Patera J, Santos EJ, Galceran MT (2004) Microwave-assisted extraction versus Soxhlet extraction for the analysis of short-chain chlorinated alkanes in sediments. J Chromatogr A 1046 19-26... 

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