ASE extract

Tao, S. et al.. Use of sequential ASE extraction to evaluate the bioavailabdity of DDT and its metabolites to wheat roots in soils with various organic carbon contents, Sci. Total Environ., 320, 1, 2004. 

FQ. Bramble, S. Frizzell, S.W George, B.A. Peterson, D.D. Ranken, J.J. Stry, and A.R. Sumpter, DuPont Project Identification AMR 3954-96 Proposed Analytical Enforcement Method For the Determination of Pyiithiobac Sodium in Cotton Gin Trash Using ASE Extraction and LC/MS/MS Analysis, Dupont, Wilmington, DE (1997). 

PFE is based on the adjustment of known extraction conditions of traditional solvent extraction to higher temperatures and pressures. The main reasons for enhanced extraction performance at elevated temperature and pressure are (i) solubility and mass transfer effects and (ii) disruption of surface equilibria [487]. In PFE, a certain minimum pressure is required to maintain the extraction solvent in the liquid state at a temperature above the atmospheric boiling point. High pressure elevates the boiling point of the solvent and also enhances penetration of the solvent into the sample matrix. This accelerates the desorption of analytes from the sample surface and their dissolution into the solvent. The final result is improved extraction efficiency along with short extraction time and low solvent requirements. While pressures well above the values required to keep the extraction solvent from boiling should be used, no influence on the ASE extraction efficiency is noticeable by variations from 100 to 300 bar [122]. 

Aromatic amines formed from the reduction of azo colorants in toy products were analysed by means of HPLC-PDA [703], Drews et al. [704] have applied HPLC/ELSD and UV/VIS detection for quantifying SFE and ASE extracts of butyl stearate finish on various commercial yarns. From the calibrated ELSD response the total extract (finish and polyester trimer) is obtained and from the UV/VIS response the trimer only. Representative SFE-ELSD/UV finish analysis data compare satisfactorily to their corresponding SFE gravimetric weight recovery results. GC, HPLC and SEC are also used for characterisation of low-MW compounds (e.g. curing agents, plasticisers, by-products of curing reactions) in epoxy resin adhesives. 

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. 

A study compared ASE and SFE to Soxhlet and sonication in the determination of long-chain trialkylamines (TAMs) in marine sediments and primary sewage sludge [89], The recoveries of these compounds by SFE at 50°C and 30 MPa with CO2 (modified dynamically with methanol or statically with triethylamine) were 10 to 77% higher than those by Soxhlet or soni-cation with dichloromethane methanol (2 1). ASE at 150°C and 17 MPa with the same solvent mixture as Soxhlet showed the highest extraction efficiency among the extraction methods evaluated. SFE exhibited the best precision because no cleanup was needed, whereas Soxhlet, sonication, and ASE extracts required an alumina column cleanup prior to analysis. SFE and ASE used less solvent and reduced the extraction time by a factor of 3 and a factor of 20 compared to sonication and Soxhlet, respectively. 

The ASE technique has also been compared — to a lesser extent, however — with ultrasound-assisted extraction (USE) and found to provide better [49,59,81] or at least similar results [31,85,109] in most cases. The advantages of ASE over USE are similar to those of the former in relation to Soxhlet extraction, i.e. increased throughput, automatability and decreased solvent consumption. While ASE extraction times are also short relative to USE, this is not the most salient advantage as USE times are also fairly short. The reduced consumption of solvents is indeed a major advantage, particularly in cases such as the extraction of organic pollutants from marine particulate matter, where... 

Increased pressure will allow the solvent to remain as a liquid (although it may be above the atmospheric pressure boiling point) and facilitate its transit through the extraction system. Changes in pressure will have little effect on analyte recovery when the applied pressure is well above the minimum required to maintain the solvent in liquid state. Typical ASE extractions work well between 1000 and 2000 psi. 

All other variables being equal, a partitioned equilibrium for the analyte between the sample matrix and the extraction solvent is reached more quickly at higher temperature and pressure because the analyte solubilization kinetics are improved. Therefore, cycle time can be much shorter for ASE extractions relative to room-temperature/pressure-solvent extractions. If certain sample variables such as pore size or structure make rapid equilibrium questionable, it is simple to design a recovery versus extraction time experiment (the results of which are shown in Figure 9) so that variability and lower recovery due to a pre-equilibrium phase separation can be avoided. The desirable extraction duration is a trade-off between the recovery and the time required to achieve it and generally runs from 10 to 17 min. 

ASE (extraction yield 80-102%), weak anion-exchange column, isocratic elution with aqueous NH4NO3, on-line ICP-MS... 

In conclusion, in this work we demonstrate the excellent capabilities of using ASE to extract compounds with antioxidant activity from natural sources as rosemary leaves and the microalga Spirulina platemis. ASE shows several advantages compared with traditional extraction processes such as 1) it is faster (IS min vs 2-24h in traditional extraction procedures) 2) it has less solvent volume consumption (13 ml vs 30>S00 mL/lOg) 3) it is more efficient (less dependant on matrix) and 4) it is automatic and allows sequential extraction of samples. The use of in-vitro assays and CE coupled to both, DAD and ESI-MS allows obtaining information about the biological and chemical properties of the ASE extracts. 

Obbard 2005). After decreasing the extraction temperature to around 100°C, the weight loss could be minimized to 2% which is comparable to that encountered upon soaking PUF in hexane (Braun et al. 1986 Wurl and Obbard 2005). Based on the results obtained, the temperature was fixed at 100°C as the optimum for ASE extraction of POPs. 

Extraction time is the time needed for POPs to desorb and dissolve most efficiently from the sample matrix into extraction solvents. In order to determine the optimum extraction time for satisfactory recovery, ASE was performed at 100°C in 40 mL of solvent mixture for 5, 10, 20, 30, 45 and 60 min, respeetively. Table 2 shows that the recovery reached a maximum between 20 and 30 min. For the time in excess of 30 min, it can be seen that the extraction yield deereased with increasing extraction time, which could be caused by a thermal degradation or the fusion of organic material within the matrix because of the temperatures reaching inside the vessels (Tao et al. 2002 PiiTeiro-Iglesias et al. 2004). It was therefore decided to use 25 min as static extraction time in all subsequent studies. In summary, the optimum ASE extraction conditions were achieved using a 3 1 HEX/ACE combination at 100°C for 25 min. 

Previously, both filters and PUF plugs spiked with standards were extracted and analyzed together. In order to determine whether the above ASE optimized conditions were suitable for filter as well as PUF samples, the ASE extractions were applied by two static cycles to standard-spiked filter/PUF samples, respectively, as described above. All recoveries of POPs by ASE are shown in Table 3. 

Figure I. Optimization of ASE extraction. C] Fipronil I r metabolite B, O metabolite C. n - 3.

Figure 5 Chromatograms of orange flavor accelerated solvent extraction (ASE) extract and standard solution.

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