Soxhlet extraction, modification

Commonly used methods for the determination of petroleum hydrocarbons in soil are modifications of the EPA method 418.1, which uses sonication or Soxhlet extraction to separate the hydrocarbons from the soil prior to either infrared spectroscopy [ 1 ] or gas chromatography with flame ionisation detection [2,3]. 

Successful complexation of the exchanged transition metals by the tetradentate ligand salen was indicated by the typical yellow/brownish colour of the prepared inclusion compounds. X-ray powder diffraction and scanning electron microscopy reveal that the crystallinity of the zeolite host is virtually retained during the modification steps. Furthermore, no crystals of the salen ligand or of metal-salen complexes are visible on the external surface of the zeolite crystallites after careful piuification via soxhlet extraction with acetone. Analysis of the used solvent by UVATS-spectroscopy revealed that only salen but no metal-salen complexes were removed from the zeolite during extraction. This indicates that the complexes are truly entrapped in the intracrystalline voids of the zeolite. It has been demonstrated [7] that the presence of salen and PdSalen in zeolite Y can be probed by IR-spectroscopy in... 

The procedure used was a modification of that described previously by Bocchi et. al., 2 j) e to the poor solubility of Na-r-PGA in dimethylsulf-oxide (DMSO), the free acid form (H-T PGA) was dissolved in DMSO and to this solution was added a five molar excess of either n-ethyl or n-propyl bromide. The reaction was allowed to continue for 48 h at room temperature after which the product was precipitated into a 6% sodium chloride aqueous solution. The precipitate was further purified by soxhlet extraction with acetone, ether, and then dried in vacuo. 

Determination of Surface Oil. A Soxhlet continuous extraction apparatus was used for removing the surface oil from the encapsulated samples. The procedures used were similar to those described previously by Anandaraman and Reineccius (16). Modifications included a reduced extraction time of 4i hours and the selection of 2-octanone as the internal standard. 

Samples were analyzed for free 3,3 -DCB using a modification of the technique described by Az, Dewald and Schnaitmann. Soxhlet toluene extractions were carried out under mild conditions to minimize pigment degradation and possible cleavage ofimide/amide DCB adducts during the course of the extraction. The samples were analyzed for 3,3 -DCB with CIS reverse phase HPLC using UV detection. Analysis results are presented in Table 2. The calculated limit of detection for the method was approximately 0.2 ppm. 

A modification of this process is extraction of the oil by placing the wet filter paper and contents in a Soxhlet thimble, extracting as usual with ether for two or three hours, then transferring the extract to a separator and washing with water as directed above. Considerably less ether is used and complete extraction is more certain. 

A modification of a procedure for the extraction of SF and SW developed by Aust (1974) was used. Approximately 10-15 dried mats of a single strain were blended with absolute ethanol and ground into a slurry. The slurry was placed into two large cellulose thimbles and extracted with the ethanolic filtrate for 24 hr in a Soxhlet extractor. The ethanol was removed from the filtrate in vacuo and the residue was... 

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