Accelerated solvent extraction ASE

Static pressurized hot solvent extraction (SPHSE), which shall henceforward be referred to as accelerated solvent extraction (ASE) for the reasons stated above, is the less flexible PHSE mode in terms of alteration or coupling to other techniques but is so far the more widely used — in fact, it accounts for over 65% of the PHSE publications reported since 1994. This is mainly the result of the sole commercially available extractor (the Dionex 200 model) implementing the static mode alone and also of the large number of studies conducted by different or even the same authors on the same analytes in the same matrices, which have therefore contributed little or nothing new in this area [58-63]. 

For example, from 1995 to 2000, more than 15 published studies on ASE involved the extraction of PAHs from soil or sediments in a virtually identical manner. 

This section discusses the principal aspects of the ASE technique, which include the steps of the extraction process, the devices used, their amenability to coupling to other operations and the most salient applications reported so far (with special emphasis on those that have introduced some innovation). In the final sub-section, ASE is compared with alternative leaching techniques. 

---

On the other hand, quantitative extraction requires complete and exhaustive extraction and no material can be lost. To assure complete extraction when a food is analyzed for the first time in a laboratory, it is useful to carry out two or three extractions, pool the solvents, and keep separate the next extracts to verify the presence of carotenoids. Usually four to six extractions are enough to remove the carotenoids completely from a sample. The extraction can be carried out in a blender, vortex, or with a mortar and pestle. Accelerated solvent extraction (ASE), an important extraction technique in residue analysis, currently attracts interest due to its short duration, low level of solvent use, and high extraction yield. The average recoveries for all carotenoids with the exception of norbixin ranged from 88.7 to 103.3% using manual extraction and from 91.0 to 99.6% by ASE (70 bar and temperature of 40°C) both extractions were carried out with a mixture of MeOH, EtOAc, and petroleum ether (1 1 1). ... 

In the past decade, new sample extraction techniques have been introduced to meet stricter criteria in the areas of food and agriculture, for example, enviromnentally friendly, non-toxic, fast, automated, robust, and cost-efficient techniques. Accelerated solvent extraction (ASE) and pressurized liquid extraction (PEE) are two methods developed for the extraction of chemicals of interest " and provide high yields and efficiency from a wide range of botanical, - animal, and biological samples. ASE and PLE combine solvents at elevated temperatures (40 to 200°C)... 

Accelerated solvent extraction (ASE) is a technique which attempts to merge the beneficial solvation properties of SFE with traditional organic solvents. Specifically, the sample is placed in an extraction vessel which can withstand high pressures while being maintained at a constant temperature. Extraction is carried out by pumping the extraction solvent through the samples for a limited time. As an example of the use of ASE, Richter and Covino extracted PCBs from a 10-g fish tissue sample with hexane... 

The need to understand the fate of pesticides in the environment has necessitated the development of analytical methods for the determination of residues in environmental media. Adoption of methods utilizing instrumentation such as gas chro-matography/mass spectrometry (GC/MS), liquid chromatography/mass spectrometry (LC/MS), liquid chromatography/tandem mass spectrometry (LC/MS/MS), or enzyme-linked immunosorbent assay (ELISA) has allowed the detection of minute amounts of pesticides and their degradation products in environmental samples. Sample preparation techniques such as solid-phase extraction (SPE), accelerated solvent extraction (ASE), or solid-phase microextraction (SPME) have also been important in the development of more reliable and sensitive analytical methods. 

B. Richter, J. EzzeU, and D. Felix, Single Laboratory Method Validation Report Extraction of Organo-phosphorus Agrochemicals, Chlorinated Herbicides and Polychlorinated Biphenyls Using Accelerated Solvent Extraction (ASE) with Analytical Validation by GC/NPD and GC/ECD, Document 101124, Dionex Sunnyvale, CA (1994). 

The main drawback of this technique is solvent and time-consuming. In the last decade, there have been efforts to develop extraction techniques that allow efficient extraction and reduced solvent volumes in shorter times, incorporating high levels of automation, such as pressurized liquid extraction (PLE) [commonly known as accelerated solvent extraction (ASE)]. 

Accelerated solvent extraction (ASE), capillary chromatography sample preparation, 4 609, 610 Accelerated temperature, humidity, and bias (THB) tests, 10 9 Accelerated weathering tests, 19 584 Acceleration, exponents of dimensions in absolute, gravitational, and engineering systems, <5 584t Accelerators, 9 554-555 10 411, 713 22 61 23 861-862 for cement, 5 485... 

More elaborate sample preparation is often needed for complex sample matrices, e.g., lotions and creams. Many newer SP technologies such as solid-phase extraction (SPE), supercritical fluid extraction (SFE), pressurized fluid extraction, accelerated solvent extraction (ASE), and robotics are frequently utilized (see Ref. [2]). Dosage forms such as suppositories, lotions, or creams containing a preponderance of hydrophobic matrices might require more elaborate SP and sample cleanup, such as SPE or liquid-liquid extraction. 

A variety of sample handling techniques is available, which can be divided into four types Soxhlet extraction, steam distillation, soni-cation and accelerated solvent extraction (ASE) [3]. 

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). 

J. Ezzelle, Accelerated solvent extraction (ASE) of pesticide residues in food roducts. GIT Lab. J. 1 (2000) 17-18. 

Extraction of semivolatile analytes collected using modified Method 5 (Method 0010) sampling train Accelerated solvent extraction (ASE) (3545A in update IVB) Ultrasonic extraction... 

In order to accelerate sample preparation, new extraction methodologies such as accelerated solvent extraction (ASE) and MAE, based on the use of elevated temperature and pressure to heat the mixture sample-solvent, have been recently developed and applied for PAH extraction from meat [695] and vegetables [696-698]. Garda Falcon et al. [699] used microwave treatment with hexane to accelerate PAH extraction from freeze-dried foods. The fat extracted in this way underwent microwave assisted saponification with ethanolic KOH. Hernandez-Borges et al. [700] combined microwave-assisted hydrolysis and extraction to isolate organic pollutants from mussels, while... 

Giergielewicz-Mozajska, H., L. Dqbrowski, and J. Namiesnik. 2001. Accelerated solvent extraction (ASE) in the analysis of environmental solid samples—some aspects of theory and practice. Crit. Rev. Anal. Chem. 31 149-165. 

As analytical capabilities improve, multiple procedures are linked together in series to effect analyses. Procedures combined in this manner are called hyphenated techniques. Ferrer and Furlong [124] combined multiple techniques—accelerated solvent extraction (ASE) followed by online SPE coupled to ion trap HPLC/MS/MS—to determine benzalkonium chlorides in sediment samples. Online SPE, especially coupled to HPLC, is being used more routinely. This approach allowed online cleanup of the ASE extract prior to introduction to the analytical column. 

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. 

Accelerated solvent extraction (ASE) is also known as pressurized fluid extraction (PFE) or pressurized liquid extraction (PLE). It uses conventional solvents at elevated temperatures (100 to 180°C) and pressures (1500 to 2000 psi) to enhance the extraction of organic analytes from solids. ASE was introduced by Dionex Corp. (Sunnyvale, CA) in 1995. It evolved as a consequence of many years of research on SFE [45], SFE is matrix dependent and often requires the addition of organic modifiers. ASE was developed to overcome these limitations. It was expected that conventional solvents would be less efficient than supercritical fluids, which have higher diffusion coefficients and lower viscosity. However, the results turned out to be quite the opposite. In many cases, extraction was faster and more complete with organic solvents at elevated temperature and pressure than with SFE. Extensive research has been done on the extraction of a variety of samples with ASE. ASE was approved by EPA as a standard method in 1996. 

---