Supercritical fluid extraction comparisons

Figure 21.8 Supercritical fluid extraction. Comparison of the solvation strength of the COj with respect to the usual solvents (HUdehrand scale) as a function of the temperature and pressure. The polarity of carhon dioxide in the supercritical state is comparable with that of hexane (for 100 atm and 35 °C). SPE is a method for which automation becomes a justified investment when the sample throughput is large. Above, sample extractor by supercritical fluids (Model SFE-703 reproduced courtesy of Dionex).

Table II. Supercritical Fluid Extraction Comparison of Hazardous Waste Samples...

COMPARISON OF ESSENTIAL OIL COMPOSITION OF SALVIA MIRZAYANII OBTAINED BY SUPERCRITICAL FLUID EXTRACTION AND HYDRODISTILLATION METHODS... 

Shen, S. et al.. Comparison of solid-phase microextraction, supercritical fluid extraction, steam distillation, and solvent extraction techniques for analysis of volatile consituents in Fructus amomi, J. AOAC Int., 88, 418, 2005. 

Bergeron, C. et al.. Comparison of the chemical composition of extracts from Scutellaria lateriflora using accelerated solvent extraction and supercritical fluid extraction versus standard hot water or 70% ethanol extraction, J. Agric. Food Chem., 53, 3076, 2005. 

Teng, W.Y., Chen, C.C., and Chung, R.S., HPLC comparison of supercritical fluid extraction and solvent extraction of coumarins from the peel of Citrus maxima fmit, Phytochem. Anal, 16, 459, 2005. 

Hinman et al. [492] have compared SFE and ASE in the extraction of antioxidants from LDPE. Comparable extraction yields were obtained with both techniques. However, sample clean-up was necessary after ASE , while with SFE the extract could be analysed directly without any post-extraction clean-up. Supercritical fluid extraction of 15 polymer additives (AOs, UVAs, process lubricants, flame retardants and antistatic agents) from eight PS formulations was compared to dissolu-tion/precipitation extractions [557], Additive recoveries were comparable. Numerous additional comparisons can be found under the specific headings of the extraction techniques (Sections 3.3 and 3.4). 

Yang Yu, Hawthorne B, Miller DJ. 1995. Comparison of sorbent and solvent trapping after supercritical fluid extraction of volatile petroleum hydrocarbons from soil. J Chromatogr A 699 265-276. 

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. 

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... 

Oostdyk TS, Grob RL, Snyder JL, et al. 1995. Supercritical fluid extraction of primary aromatic amines from characterized soil samples comparison with sonication extraction. J Environ Sci Health A30(4) 783-816. 

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). 

Figure 20.6—Supercritical fluid extraction. A comparison of the solvation strength of CO2 with classical solvents (Hildebrand scale) as a function of temperature and pressure is shown.

R Marsili, D Callahan. Comparison of a liquid solvent extraction technique and supercritical fluid extraction for the determination of a- and /8-carotene in vegetables. J Chromatogr Sci 31 422-428, 1993. 

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. 

Figure 8. Comparison of the solubilities of hyoscyamine (A) and scopolamine (B) hydrochloride using methanol basified with diethylamine (10% v/v) with those of pure methanol at 60 C, 34.0 MP [39]. Reprinted from J. Chromalogr. A, 863, Y. H. Choi et al., Strategies for supercritical fluid extraction of hyoscyamine and scopolamine salts using basified modifiers, 47-55,1999, with permission from Elsevier Science.

D. L. Allen, K. S. Scott and J. S. Oliver, Comparison of sohd-phase extraction and supercritical fluid extraction for the analysis of morphine in whole blood , J. Anal. Toxicol. 23 216-218 (1999). 

This article treats the benefits, possibilities and drawbacks of supercritical fluid chromatography (SFC) and supercritical fluid extraction (SFE) coupled to nuclear magnetic resonance spectroscopy. After a general overview and consideration of the motivation for such techniques, the design of high-pressure flow probes, as well as the principle experimental set-ups, are described. By means of several applications and comparison to HPLC-NMR, the utility of these hyphenated techniques is demonstrated. 

Combination of static subcritical water extraction and solid-phase microextraction Comparison of CHC1F2, N2O and CO2 extractants. CHC1 F2 gave highest recovery, methanol-modified CO2 gave 90% recovery Combination of supercritical fluid extraction with off-line Fourier transform infrared spectroscopy... 

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

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. 

Alzaga, R., G. Durand, D. Barcelo, and J.M. Bayona (1994). Comparison of supercritical fluid extraction and liquid-liquid extraction for isolation of selected pesticides stored in freeze-dried water samples. Chromatographia, 38(7-8) 502-508. 

Eskilsson, C.S., K. Hartonen, L. Mathiasson, et al. 2003. Pressurized hot water extraction of insecticides from process dust—comparison with supercritical fluid extraction. J. Sep. Sci. 27 59-64. 

X. Chaudot, A. Tambute and M. Caude, Comparison of supercritical fluid extraction with solvent sonication for chemical warfare agent determination in alkyd painted plates, J. High Resolut. Chromatogr., 21, 457-463 (1998). 

For purposes of comparison, some supercritical fluid extraction processes have been calculated in which the extract is separated at the subcritical pressure p = 60 bar (Process 4). Such a process corresponds to that in Fig. 1 with the difference that a pump is employed to increase the pressure from state 1 to state 2, since the CO2 is cooled down to 17°C after separation, i.e. is present in the liquid state before the pressure is increased. Even for the most favourable variant with K = 0.062 DM/kg hop extract, the operating costs for this process are significantly higher than for processes employing supercritical separation. They can be reduced significantly by heat recovery with a heat pump as published by Sievers and Eggers 3. ... 

Figure 2. Comparison of energy costs K in DM/kg hop extract for supercritical fluid extraction of hops with C02 according to Processes 1 to 3.

Bielska, L., Smidova, K., Hofman, J. Supercritical fluid extraction of persistent organic pollutants from natural and artificial soil and comparison with hioaccumulation in earthworms. Environ. Pollut. 176, 48-54 (2013)... 

Solid-phase extraction (SPE) is nearly always required prior to the supercritical fluid extraction of PAHs from liquid samples alternatively, samples can be spiked to a solid material such as diatomaceous earth. A comparison of SPE, SFE, SPE-SFE and liquid-liquid extraction (LEE) for the removal of PAHs from drinking water revealed the SPE-SFE combination to provide the best results and LLE the poorest [188]. 

Supercritical fluid extraction (SFE), usually with carbon dioxide and, often, with a modifier, has become of increasing interest in the last few years because of its selectivity, preconcentration effect, efficiency, simplicity, rapidity, cleanness, and safety, mainly concerning the extraction of organic compounds prior to separation and detection by chromatographic techniques. It has several advantages over classical solvent extractions, in comparison with recent extraction techniques. Approaches to obtain quantitative extractions, including fluid choice, extraction flow rate, modifiers, pressure, and temperature, are presented, as well as the potential for SFE to extract polynuclear aromatic hydrocarbons (PAHs) from soils, sediments, and biota. Improvements and new environmental applications are also reported. 

Tena, M.T., Valcarel, M., Hidalgo, PJ. and Ubera, J.L. 1997. Supercritical fluid extraction of natural antioxidants from rosemary comparison with liquid solvent sonication. Analytical Chem. 69 521-526. 

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