Comparison of extraction

Anand, R. et al.. Comparison of extraction techniques for extraction of bioactive molecules from Hypericum perforatum L. plant, J. Chromatogr. Sci., 43, 530, 2005. 

Table 3.22 Comparison of extraction methods for polyamide samples...

Validation of extraction procedures is frequently lacking. A good assessment of quality assurance implies that the extraction recoveries are verified, e.g. by spiking of standard addition. A major drawback is that the spike is not always bound the same way as the compounds of interest. For the development of good extraction methods, materials with an incurred analyte (i.e. bound to the matrix in the same way as the unknown), which is preferably labelled (radioactive labelling would allow verification of the recovery), would be necessary. Such materials not being available, the extraction method used should be validated by other independent methods, e.g. by verification against known samples and by use of a recovery SPC chart. A mere comparison of extraction methods is no validation. 

Table 3.48 Comparison of extraction performance of polymer/additive systems...

Comparison of Extraction Yields Between Different Digesters... 

Figure 11.10 Comparison of extracted ion pyrograms of fragment ion m/z 217 of two samples collected from the paint surfaces of Universal Judgement and Stories of Holy Fathers (Monumental Cemetery of Pisa, Italy, painted by Buffalmacco, fourteenth century) with nitro cellulose, starch and arabic gum. 1, Unidentified compound 2, 1,2,3,5 tetrakis (O TMS) xylo furanose 3, tri (O TMS) levoglucosane 4, isomer of 1,2,3,5 tetrakis (O TMS) xylofuranose. Pyrogram obtained with a resistively heated filament at 60CPC in the presence of HMDS [30]...

Army. 1985a. Comparison of extraction techniques and solvents for explosive residues in soil. Order no. A1-5-R0001-XX-A1-48. Aberdeen Proving Ground, MD U.S. Army Toxic and Hazardous Materials Agency. Document no. AD A2205888. 

Jenkins TF, Grant CL. 1987. Comparison of extraction techniques for munitions residues in soil. 

The present authors studied the extraction of aromatic amines into ILs. As is seen from experimental data for [C4CiIm][PFg] (Figure 9.2), aniline, napthylamine, and o-toluidine are efficiently extracted from the alkaline aqueous solution. Thus, as in the case of phenols, neutral (molecular) forms of solutes were extracted. Another example of the same behavior is given by many polyfunctional compounds, for example, 8-hydroxyquinoline (Figure 9.3 presents a comparison of extraction pH-profile with the distribution diagram for ionic forms of the solute). 

A comparison of extraction methods for primary aromatic amines including 1,4-phenylenediamine, 2,4-diaminotoluene, benzidine, 4,4 -methylenebis (2-chloroanilme), 3,3 -dimethylbenzidine, and 3,3 -dichlorobenzidine from solid matrices was conducted. Supercritical fluid extraction (SEE) was evaluated and compared with the classical method, sonication extraction (Oost-dyk et al., 1993). 

Fawkes J, Albro PW, Walters DB, et al. 1982. Comparison of extraction methods for determination of polybrominated biphenyl residues in animal tissue. Anal Chem 54 1866-1871. 

Figure 2. Comparison of extractable organic (CH2CI2) levels in uncleaned and cleaned XAD-2 resin.

Baublis, A., Spomer, A., and Berber-Jimenez, M.D. 1994. Anthocyanin pigments Comparison of extract stability. J. Food Sci. 59 1219-1221, 1233. 

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. 

A limitation to the use of modifiers in SFC has been the detector compatibility of the specific modifier. For example, most modifiers (i.e. methanol) provide a flame ionization detector response preventing use at a large concentration. In SFE, however, this limitation does not exist since modifiers can be used in a mixed mode with CCb and the sample. Figure 1 (taken from reference 25) shows an example of the use or modifiers in SFE. Here the comparison of extraction efficiencies obtained using CO and CO2 modified with methanol is shown. The matrices extracted in these SFE experiments were an XAD-2 sorbent resin and soils. The target analytes were dibenzo[a,i]-carbazole, diuron, 2,3,7,8-tetrachorodibenzo-p-dioxin (TCDD) and linear alkylbenzenesulfonate (LAS) detergent. For each of these respective analytes the extraction efficiency increased dramatically with the use of C02/methanol modifier compared to pure CO2 only as the extracting fluid. This was even the case for the ionic compounds namely, the linear alkylbenzenesulfonates (LAS), which were quantitatively recovered. 

Kuchroo, C. N. and Fox, P. F. (1982a). Soluble nitrogen in Cheddar cheese Comparison of extraction procedures. Milchwissenschaft 37, 331-335. 

Spjuth, L., Liljenzin, J-O., Hudson, MJ. et al. 2000. Comparison of extraction behaviour and basicity of some substituted malonamides. Solvent Extr. Ion Exch. 18 (1) 1-23. 

From the studies published, it appears that it may be possible to improve the radio-lytic stability of an extractant system. Of course, it is difficult to obtain a universal proposal, and the various experimental conditions selected to perform the radiation experiments (nature of the diluents, acidity, and the presence of other solutes either in the aqueous or organic phase) have made the comparison of extractants stability difficult. Nevertheless, systematic tendencies have been summarized in the following section, related to the modification of the extractant alone or related to the composition of the solvent (organic phase). 

Study of polar extraction solvents comparison of extraction solvents... 

Hayes, M. H. B., R. S. Swift, R. E. Wardle, and J. K. Brown. 1975. Humic materials from organic soil A comparison of extractants and properties of extracts. Geoderma 13 231-245. 

Kim, B.-H., Lee, S.-J., Kim, H.-S., Chang, Y.-S., 2004a. Determination of polychlorinated dibenzo-p-dioxins and dibenzofurans and comparison of extraction methods for edible freshwater fish and frogs in South Korea by using a high-resolution GC/MS. Food Additives and Contaminants 21, 700-710. 

Comparison of Extractive Processes in HF Contactors and Pertraction through ELM... 

J. R. Dean, Comparison of extraction methods, in Extraction Methods for Environmental Analysis, Wiley, Chichester, West Sussex, England, 1998,... 

S. Mounicou, J. Szpunar, R. Lobinski, D. Andrey, C. J. Blake, Bioavailability of cadmium and lead in cocoa comparison of extraction procedures prior to size-exclusion fast-Bow liquid chromatography with inductively coupled plasma mass spectrometric detection (SEC-ICP-MS), J. Anal. Atom. Spectrom., 17 (2002), 880D886. 

F. Yang, R. E. Sturgeon, S. McSheehy, Z. Mester, Comparison of extraction methods for quantitation of methionine and selenomethionine in yeast by species specific isotope dilution gas chromatography-mass spectrometry, J. Chromatogr. A, 1055 (2004), 177-184. 

J. A. Brisbin, J. A. Caruso, Comparison of extraction procedures for the determination of arsenic and other elements in lobster tissue by inductively coupled plasma mass spectrometry, Analyst, 127 (2002), 921D929. 

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