Ultrasonic extraction comparison with Soxhlet

Comparison of Soxhlet, ultrasonic, SFE, and PLE for high and low PAH contaminated soils showed that the best results were achieved using PLE with acetone - toluene 1 1 but PLE or ultrasonic extraction with just acetone was adequate when performing subsequent HPLC analysis. Another comparisons of sample preparation of sewage sludge showed no real differences in the recoveries of PAHs by Soxhlet, SFE, USE, PLE, or MAE when each method was optimized. ... 

Ultrasonic extraction of the pesticides atrazine, propham, chlorpropham, diflubenzuron, alpha-cypermethrin, and tetramethrin from soil was optimized in terms of the solvent (acetone), duration of sonication, and number of extraction steps. Comparisons with shake-flask and Soxhlet extractions made using reversed-phase (RP) TLC on C-18 plates showed advantages in extraction efficiencies, simplicity of use, and low-solvent consumption for ultrasonic extraction. ... 

The main comparisons between extraction methods have been made between the Soxhlet, ultrasonication, and supercritical fluid extraction [377, 398,456,461,462]. This has primarily been prompted by the need to evaluate critically the relative merits of SFE as an alternative to the more established methods. Richards and Campbell [456] made a comparison between SFE, Soxhlet, and sonication methods for the determination of some priority pollutants in soil. The SFE apparatus was the same, relatively standard system as described by Campbell et al. [457] with the addition of a C02 cryogenic trap to... 

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.

Most papers dealing with phenolic acid HPLC analysis in herbs describe only simple liquid extraction without the hydrolysis step. Acetone, methanol, or alcoholic-water or acetone-water mixtures are applied. Very rarely, pure water is used as the extraction solvent. " It was found that the extraction recoveries for water extracts are often lower in comparison to alcoholic-water mixtures, especially when the simultaneous separation of polar and less polar phenolic acids has been performed. Sometimes, the control of pH can improve the recovery. If necessary, n-hexane, chloroform, diethyl ether, benzene-acetone, petroleum ether, or other less polar solvents are recommended for removing interfering compounds. The extraction is usually performed by refluxing the samples for a specific time in a Soxhlet apparatus, with simple mechanical or magnetic stirring of the sample with the extraction solvent, or by plant sample maceration. The application of an ultrasonic bath for the liquid extraction has also become popular in recent years. The hydrolysis steps have also been recommended for medicinal species preparation, especially when other phenolic compounds are also analyzed simultaneously with phenolic acids in herbs. 

In 1991, the SFE of a novel corticosteroid, tipredane, from rodent diet was reported (78). The authors investigated the extraction of the tipredane with and without the presence of ethanol as modifier, obtaining the best results with a 10 1 C02 thanol mixture. A comparison of the optimized SFE conditions with more conventional extraction procedures such as Soxhlet and ultrasonic agitation was performed. The average recovery obtained with SFE was 85% as compared with 92% obtained by ultrasound agitation and 94% by Soxhlet. The main advantage of SFE was the shorter extraction time needed and no preconcentration step required prior to FIPLC analysis. 

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