Sonication extraction results

It is not uncommon that extraction techniques are unfairly compared. Appropriate interlaboratory studies are few. Soxhlet and sonication extraction (EPA methods 3540 and 3550, respectively) were compared in an interlaboratory study (129 participants) for PCBs in soil. Results from laboratories using Soxhlet extraction were significantly more accurate than those obtained using sonication, especially at higher concentrations, but with equal precision [196]. This is rationalised by the observation that the Soxhlet procedure presents the sample with fresh solvent so that the extraction solvent is never saturated, unlike the sonication procedure. Sonication is very sensitive to the solvent polarity, nonpolar solvents producing considerably less accurate results than polar solvents. It is not as sensitive to clean-up procedures as... 

The organoarsenical particulates are extracted ultrasonically from the filters for 30 minutes in 25 mL of an aqueous carbonate/ bicarbonate/borate buffer (Eluent 1, Table I). After sonication the resulting extracts are ready for analysis and no further sample preparation is necessary. 

It was mentioned above that the carboxyl carbon is lost in the conversion of anthranilic acid to indole. Consequently, two additional carbon atoms must be supplied to complete the pyrrole ring of the indole. The observation that various ribose derivatives could be the source of these two carbons provided the clue that led to the elucidation of the mechanism of indole synthesis in the tryptophan biosynthetic pathway (232). Yanofsky determined that sonic extracts of a tryptophan auxotroph of E. cdi (that also grew on anthranilic acid or indole) could utilize ribose, ribose 5-phosphate, and 5-phosphoribosylpyrophosphate to form indole from anthranilic acid. With the two former compounds, ATP was essential for the reaction, with the latter compound it was not. This result made it appear evident that 5-phosphoribosylpyrophosphate was the more immediate reactant in the condensation with anthranilic acid. 

The enzymatic synthesis of the actinomycin chromophore also has been described (Weissbach and Katz, 1961 Katz and Weissbach 1962 Salzman, Weissbach and Katz, unpublished results). An enzyme, designated phenoxa-zinone synthetase, was obtained from sonic extracts of S. antihioticus and was shown to catalyze the oxidative condensation of o-aminophenols to the corresponding phenoxazinone. When 3-hydroxy-4-methylanthranilic acid (4MHAA) was used as substrate, actinocin was synthesized. The enzyme has been purified approximately 25- to 30-fold from sonic or French pressure cell extracts of the organism by means of standard protein fractionation procedures (ammonium... 

Wang and Zhang also investigated the effects on the xylan extracted from corn cobs enhanced by ultrasound at various lab-scale conditions. Results showed that the optimization conditions of xylan extraction should be carried out using (i) 1.8 M NaOH, (ii) corn cobs to NaOH solution ratio of 1 25 (w/w), (iii) sonication at 200 W ultrasound power for 30 min at 5 min intervals, and (iv) 60 °C (Wang Zhang, 2006). 

In general, the physical structure of the tissue must be broken down mechanically followed by an extraction procedure, before the sample can be analyzed. Homogenization using blenders, probe homogenizers, cell disrupters, sonicators, or pestle grinders is particularly useful for muscle, liver, and kidney samples. Regardless of the method used for tissue disruption, the pulse, volume of extraction solvent added, and temperature should be validated and standardized in order to ensure reproducible analytical results. During cell disruption, care should be taken to avoid heat build-up in the sample, because the analyte may be heat labile. 

Van Emon et al. ° developed an immunoassay for paraquat and applied this assay to beef tissue and milk samples. Milk was diluted with a Tween 20-sodium phosphate buffer (pH 7.4), fortified with paraquat, and analyzed directly. Fortified paraquat was detected in milk at less than 1 pgkg , a concentration which is considerably below the tolerance level of 10 pg kg Ground beef was extracted with 6 N HCl and sonication. Radiolabeled paraquat was extracted from ground beef with recoveries of 60-70% under these conditions. The correlation coefficient of ELISA and LSC results for the ground beef sample was excellent, with = 0.99, although the slope was 0.86, indicating a significant but reproducible difference between the assays. 

In order to increase the overall extraction efficiency during SFE sonication has been applied [352]. Ultrasound creates intense sinusoidal variations in density and pressure, which improve solute mass transfer. Development of an SFE method is a time-consuming process. For new methods, analysts should refer the results to a traditional sample preparation method such as Soxhlet or LLE. 

Producing data that cannot be compared directly with other total petroleum hydrocarbons data or guidelines because one data set is the result of a Soxhlet extraction method and the other reflects a sonication or other alternative extraction method. 

Fusion protein pull-down assays involve the overexpression of bait and/or fusion proteins in bacteria. Often, the expressed fusion proteins are localized in occlusion bodies and not readily soluble under nondenaturing conditions. The expressed proteins can be extracted using urea, sonication, sodium dodecyl sulfate (SDS), or a combination of all the three. The net result is the denaturation of the recombinant protein and it may need to be refolded if the interaction domain is conformationally dependent. A major advantage of the pull-down assay is that high concentrations of proteins can be easily generated thus favoring protein association for a reversible equilibrium between two proteins. 

Extraction of samples. Plant tissues were lyophilized after harvest and ground to a homogeneous powder in a Wiley mill (no. 20 mesh). Samples (0.500 g) of lyophilized whole leaf were extracted in 125 mL roundbottom flasks by steeping in 25 mL of chloroform for 30 min. The extract was filtered and the filtrate set aside. The extraction flask and filtered solids were rinsed with an additional 15 mL of fresh chloroform. The filtrate from the rinse was then combined with the original filtrate and the resulting solution was evaporated to dryness with a rotary evaporator. The dry solids were redissolved in a mixture of 20.0 mL methanol and 5.0 mL acetone using sonication to assist in dissolving of all solid material. 

Both marine sediment and soil samples were investigated by the developed assay. These were first either Soxhlet extracted or sonicated to isolate the PCB fraction. An aliquot of the resulting extract was then taken and the associated solvent allowed to evaporate before examination by the new assay. Detection limits for the Aroclor 1248, 1242 and 1254 mixtures were reported to be 0.4, 0.3 and 0.5 ngml-1, respectively. 

Results obtained from the analysis of marine sediment and soil samples, extracted by the sonication-assisted method... 

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