Accelerated solvent extractor

Dionex Accelerated Solvent Extractor (ASE200) with 11- and 22-mL extractor cells... 

Wennrich et al. [167] investigated the capabilities of coupling accelerated solvent extraction with water as the extraction solvent and solid-phase microextraction to determine chlorophenols in polluted soils. Subcritical water extraction was performed using a commercially available accelerated solvent extractor. This system solves the problem of the analytes partitioning back to the soil matrix, which can occur in straightforward subcritical water extraction because in the Wennrich et al. method [167] the aqueous phase and the soil are separated under the extraction conditions. 

The ground plant samples are weighed (typically 7 to 20 g, depending on plant part) and extracted in a semi-automated process utilizing a Dionex ASE300 accelerated solvent extractor system. The samples are placed in stainless steel cells and sealed. Approximately 33 to 66 mL of 95% EtOH are added and the cells are placed under 1500 PSI, preheated for 5 min to 40°C and held at this temperature... 

ASE 200, Accelerated Solvent Extractor Operator s Manual, Dionex Corp., Document No. 031149, Revision 03, Sunnyvale, CA (1997). 

Begin this method with the Soxhlet extraction of approximately 1 to 10 g of soil or sediment with 90% methanol/10% distilled water. The methanol will effectively wet the soil and sediments and remove the majority of the organochlorine pesticides. Alternatively, the soils and sediments may be extracted with heated solvent under pressure using the accelerated solvent extractor by Dionex (see Chapter 9 on the extraction of food and natural materials for details of analysis). After the extraction is complete, dilute the methanol extract with distilled water to a final concentration of 10% methanol. Process the extract through a C-18 cartridge as described in Section 7.10.1. In this case, the C-18 sorbent with greater hydrophobicity is used because of the 10% methanol present in the sample. Elute the cartridge with ethyl acetate and analyze by GC/MS. 

Extractant 90% methanol/10% distilled water, extract twice with 20 mL each time with Soxhlet, heated vial, or accelerated solvent extractor. Dilute to 360 mL total with distilled water and then process by SPE. 

Deethylatrazine, deisopropylatrazine, and didealkylatrazine. 90% methanol/10% distilled water, extract twice with 20 mL each time with Soxhlet, heated vial, or accelerated solvent extractor. Evaporate the majority of the methanol off sample under nitrogen, then process aqueous extract (- 4 mL) by SPE. 1 g of SDB, precondition with 2 mL each of methanol, ethyl acetate, methanol, and distilled water. 

Figure 9.2. Photograph of an accelerated solvent extractor (ASE). (Copyright and courtesy of Dionex Corporation, Sunnyvale, California.)...

Carbon dioxide is pumped from the bottom of the liquid tank and compressed, heated, and then the samples are extracted (Fig. 9.3). The analytes are trapped in an organic solvent as the carbon dioxide is vented from the extractor. Supercritical fluid extraction (SFE) involves some experimentation with the proper pressure to achieve the extraction of the analyte of interest. Several vendors sell the automated supercritical fluid extractors. Both the accelerated solvent extractor and the supercritical fluid extraction are expensive methods, in the price range of 50,000 each. Several general reviews of SFE include Gere and Derrico (1994), Smith (1995), and a general sample preparation review by Majors (1995). 

In this study, an ASE 200 Accelerated Solvent Extractor, Dionex Corp. (Sunnyvale, CA, USA) was used. The extraction cells (Dionex) were of stainless steel with a volume of 11 ml and capped with PEEK seals and stainless steel frits. 

Sediments were added with anhydrous sodium sulphate and extracted on an accelerated solvent extractor with 66,109... 

More efficient devices are commercially available. One of these is the Accelerated Solvent Extractor sold by DIONEX, " where the extraction takes place in a closed vessel in which temperatures of 100°C and pressures up to 2000 psi are reached even with low boiling solvents. 

Filter samples were extracted with a hexane acetone solvent (3 2) mixture using an accelerated solvent extractor. The aqueous and organic solvent phases obtained were separated and the aqueous phase was extracted three times with n-hexane. Cleanup was performed as for the water samples. 

Filters were extracted using an accelerated solvent extractor with n-hexane/acetone (3 2) mixture. Water was added to the extracts and treated as for the XAD extracts. 

FIGURE 15.11 Schematic diagram of the accelerated solvent extractor (courtesy of Dionex Corp.)... 

ASE 200 Accelerated Solvent Extractor Operators Manual, Document 031149, Rev. 01, Dionex Corp. 1995. 

PFE procedures for the soil were carried out in an Accelerated Solvent Extractor (ASE, Dionex Corporation, Salt Lake City, Utah). The extraction method was optimized by varying extraction temperature and number of extraction cycles. The extraction solvent was acetonitrilermethanol (1 1, v v) and the pressure was kept constant at 1500 psi, which in previous studies pressure did not show a big influence on the extraction efficiency (13), The soil used for optimization was of the Helemano series (14), spiked in the laboratory by the organic solvent slurry method (15) at approximately 3 pg/g for each of the analytes. After extraction, the sanq)les were filtered through sodium sulfate and 0.2 pm nylon filter and concentrated with a gentle flow of nitrogen gas before GC-MS analysis. 

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