Soxhlet extractions comparison

The obtained gels were purified by Soxhlet extraction with chloroform to remove the unreacted polyoxazoline. Table 6 summarizes the results of the preparation of polymer hybrids together with their water adsorptions. In comparison with the silica gel without polyoxazoline segments, the modified silica with 50% polyoxazoline was found to show higher water adsorption. 

Shen, J. and Shao, X., Comparison of accelerated solvent extraction, Soxhlet extraction, and ultrasonic-assisted extraction for analysis of terpenoids and sterols in tobacco. Ana/. Bioanal. Chem., 383, 1003, 2005. 

Soxhlet extraction is well established, and generally exhaustively extracts all additives. The selection of extraction solvent can make large differences to the extraction time. The generally long extraction times followed by concentration steps may determine losses of volatile or thermally labile components. Because this form of extraction is one of the oldest and still widely used in industry, it is the standard to which many of the newer extraction technologies (which are likely to determine future applications) are referred. However, it should be realised that extraction mechanisms may be different, and thus comparisons are sometimes irrelevant. 

V. Lopez-Avila, Sonication and Soxhlet Extraction in Environmental Analysis Methods Comparison. EPA Report 600/X-93/010, US Environmental Protection Agency Environmental Monitoring Systems Laboratory, Las Vegas, NV (February 1993). 

PCBs in biological samples are usually extracted by a Soxhlet column and with a nonpolar solvent such as hexane. The sample is first mixed with sodium sulfate to remove moisture. The extraction of PCBs from sediments was tested with sonication, with two sonications interspersed at a 24-h quiescent interval, with steam distillation, or with Soxhlet extraction (Dunnivant and Elzerman 1988). Comparison of the recoveries of various PCB mixtures from dry and wet sediments by the four techniques and the extraction efficiency of four solvents showed that the best overall recoveries were obtained by Soxhlet extraction and the two sonication procedures. In comparisons of solvent systems of acetone, acetonitrile, acetone-hexane (1+1), and water-acetone-isooctane (5+1.5+1), recoveries of lower chlorinated congeners (dichloro- to tetrachloro-) were usually higher with acetonitrile and recoveries of higher chlorinated congeners (tetrachloro- to heptachloro-) extracted with acetone were superior (Dunnivant and Elzerman 1988). The completeness of extraction from a sample matrix does not seem to discriminate against specific isomers however, discrimination in the cleanup and fractionation process may occur and must be tested (Duinker et al. 1988b). 

Table 2.2 shows a comparison of various extraction methods for solid samples [17]. It appears that one can take anywhere from 0.1 to 24h for the extraction process. Microwave-assisted sample preparation requires minimal time however, if cost is a consideration, Soxhlet extraction is least costly but requires the longest sample preparation time. 

Snyder JL, Grab RL, McNally ME, et al. 1992. Comparison of supercritical fluid extraction with classical sonication and soxhlet extractions for selected pesticides. Anal Chem 64 1940-1946. 

S.B. Hawthorne, C.B. Grabanski, E. Martin and D.J. Miller, Comparison of Soxhlet extraction, pressurized liquid extraction, supercritical fluid extraction and subcritical water extraction for environmental solids recovery, selectivity and effects on sample matrix. J. Chromatogr.A 892 (2000) 421 133. 

Figure 3 shows a comparison between the two methods. The ultrasonically cleaned resin has 10 more contaminant peaks than the Soxhlet-extracted resin. However, the ultrasonic procedure achieves almost the same results as Soxhlet extraction in one-fourth the elapsed time. 

Figure 3. Capillary GC profile comparison of resin cleanup procedures by ultrasonic bath and Soxhlet extraction. Y-axis 1E2 — 0.005 ng/L to 1 E4 = 0.5 ng/L. The resin was extracted with methanol, acetonitrile, and methylene chloride. Fifty milliliters of resin was placed in a column and eluted with 2 bed volumes (50 mL) of methylene chloride. The third bed volume was concentrated to 1 mL, and 2.5 pL was injected into the GC. This sample represents a sample elution quality assurance control blank.

Environmental applications of SFE appear to be the most widespread in the literature. A typical example is the comparison of extraction efficiency for 2,3,7,8 -tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) from sediment samples using supercritical fluid extraction and five individual mobile phases with Soxhlet extraction was made (101). The mobile phases, carbon dioxide, nitrous oxide, pure and modified with 2% methanol as well as sulfur hexafluoride were examined. Pure nitrous oxide, modified carbon dioxide and modified nitrous oxide systems gave the recoveries in the acceptable range of 80 to 100%. Carbon dioxide and sulfur hexafluoride showed recoveries of less than 50% under identical conditions. Classical Soxhlet recoveries by comparison illustrated the poorest precision with average extraction efficiencies of less than 65%. Mobile phase choice, still as yet a major question in the science of supercritical fluid extraction, seems to be dependent upon several factors polarity of the solute of interest, stearic interactions, as well as those between the matrix and the mobile phase. Physical parameters of the solute of interest, as suggested by King, must also be considered. Presently, the science behind the extraction of analytes of interest from complex matrices is not completely understood. 

Table VIII. Recovery of Waxes from Polystyrene Comparison of SFE vs. Soxhlet Extraction...

A comparison has been made between SFE and Soxhlet extraction methods in regards to recovery of analyte, speed of extraction, and relative cost per extraction (15). Such comparative studies are dependent, as is our study, not only upon the extraction conditions used but upon the type and cost of the equipment. The investigation described in this paper compares SFE with standard Soxhlet methods in terms of extraction time, analyte recovery, method simplification, environmental hazards, portability, and cost per extraction using a commercially available SFE system. 

As an extraction technique, SFE proved to give comparable recoveries to those of Soxhlet extraction. In all cases, SFE dramatically shortened extraction times and minimized most environmental hazards, solvent concentration steps, and waste disposal costs. A summary of this comparison is included as Table XII and is a projected cost comparison of SFE to Soxhlet extraction, based on our experiences with the SFE system used in these studies (Isco SFE System 1200). The projected cost per extraction was determined to be 15.85(SFE) vs. 22.60(Soxhlet). 

Polychlorodibenzo p-dioxins and benzofurans Comparison of Soxhlet extraction using (a) toluene and (b) methylene dichloride-acetone [90,103]... 

Organochlorine insecticides co2 - Comparison with Soxhlet extraction [170]... 

Organochlorine, organophosphorus insecticides C02-3% methanol Comparison with classical sonication and Soxhlet extraction [165,167]... 

Chlordane co2 Comparison of supercritical fluid extraction, accelerated solvent extraction and Soxhlet extraction [275, 277-280]... 

In order to improve oxidative stability, supercritical C02 fluid extraction could be used for flaxseed oil extraction (Bozan and Temelli, 2002). This method demonstrated higher ALA content compared to soxhlet extraction. In contrast, tocopherol content was lower (Table XI). Temperature and pressure profiles did not alter the fatty add profile and exhibited similar results at 50 and 70°C and pressures of 35 and 55Mpa. Stability of oil was not reported, and since limited knowledge is available further research is required with regards to shelf life and comparisons to cold-pressing operation. 

Comparison of simple methanol extraction, Soxhlet extraction, pressurized liquid extraction (PLE), and supercritical fluid extraction (SFE) shows (Clausen et al., 2003) that DEHP can be extracted relatively easily from dust and that the effectiveness does not differ significantly between the different extraction methods (see Figure 2.4). Selection of the optimal method depends on several circumstances, for example number of extraction cycles, instrument accessibility and the analysis method. However, PLE using cyclohexane/acetone was chosen as the preferred extraction method in the field study. 

Ryno, M., L. Rantanen, E. Papaioannou, A.G. Konstandopoulos, T. Koskentalo, and K. Savela. 2006. Comparison of pressurized fluid extraction, Soxhlet extraction and sonication for the determination of polycyclic aromatic hydrocarbons in urban air and diesel exhaust particulate matter. J. Environ. Monit. 8 488 193. 

Like Soxhlet, sonication is also recognized as an established conventional method, although it is not as widely used. Limited research has focused on sonication per se or its comparison with Soxhlet. Qu et al. [13] developed a method using sonication with methanol for the extraction of linear alkylbenzene sulfonate (LAS) in plant tissues (rice stems and leaves). Both efficiency and accuracy were found to be high. The mean recovery was 89% (84 to 93% for LAS concentration of 1 to 100 mg/kg), and the relative standard deviation (RSD) was 3% for six replicate analyses. Its advantages over Soxhlet extraction were speed (1 hour), less solvent consumption, and smaller sample requirement (2 to 3 g). 

A chronological approach is good for evaluation of past work (e.g. the development of the concept of aromaticity), whereas a step-by-step comparison might be best for certain exam questions (e.g. Discuss the differences between solid phase and Soxhlet extraction in the analysis of pesticides ). There is little choice about structure for practical and project reports (see Chapter 52). 

COMPARISON OF THE EXTRACTION EFFICIENCIES OF ASE AND SOXHLET EXTRACTION IN SOILS FROM SOUTHERN RUSSIA (CONCENTRATIONS ARE GIVEN IN ng/g DRY MASS)... 

COMPARISON OF SOXHLET EXTRACTION FOR 24 H WITH ASE (I BATCH CYCLE) OF AGED CONTAMINATED SOIL USING DICHLOROMETHANE AS EXTRACTANT... 

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