Supercritical carbon dioxide extraction analysis

Supercritical carbon dioxide effectively extracts the nonpolar compounds from aU soil types. The extraction of more polar compounds, such as chlo-rophenols and some pesticides requires that a polar compound, such as a short-chain alcohol is added to the carbon dioxide. Supercritical carbon dioxide extraction is used by environmental analysis laboratories as a more efficient, occupationally more acceptable method for analyzing contaminated soils (Laitinen et al., 1994). 

Reverchon E, Senatore F. Supercritical carbon dioxide extraction of chamomile essential oil and its analysis by gas chromatography-mass spectrometry. J Agric Food Chem 1994 42 154-158. 

Reverchon, E., and F. Senatore. 1994. Supercritical Carbon Dioxide Extraction of Chamomile Essential Oil and Its Analysis by Gas Chromatography-Mass Spectrometry. Journal of Agricultural and Food Chemistry 42 (1) 154-158. 

Hops can be extracted with a wide range of solvents. Most popular today are the liquid or supercritical carbon dioxide extracts and the ethanol extracts. LC analysis of... 

The dense fluid that exists above the critical temperature and pressure of a substance is called a supercritical fluid. It may be so dense that, although it is formally a gas, it is as dense as a liquid phase and can act as a solvent for liquids and solids. Supercritical carbon dioxide, for instance, can dissolve organic compounds. It is used to remove caffeine from coffee beans, to separate drugs from biological fluids for later analysis, and to extract perfumes from flowers and phytochemicals from herbs. The use of supercritical carbon dioxide avoids contamination with potentially harmful solvents and allows rapid extraction on account of the high mobility of the molecules through the fluid. Supercritical hydrocarbons are used to dissolve coal and separate it from ash, and they have been proposed for extracting oil from oil-rich tar sands. 

Topal, U. et al.. Extraction of lycopene from tomato skin with supercritical carbon dioxide effect of operating conditions and solubility analysis, J. Agric. Food Chem., 54, 5604, 2006. 

A 1-g sieved, air-dry soil sample is placed in an extraction cell with methanol as a modifier. The sample is extracted at a C02 flow rate of 1.5 mT/min with supercritical carbon dioxide for 15 minutes and analytes trapped in an octadecyl siloxane microextraction disk for subsequent analysis (adapted and condensed from Reference 9). 

Extraction of fat by supercritical carbon dioxide was investigated as an important option for minimizing the expanded use of frequently flammable and carcinogenic solvents in food analysis. Unfortunately, the presence of moisture in foods has an adverse effect on the quantitative extraction of fat by supercritical fluid extraction (SEE). Hence, samples have to be lyophilized first. The total fat content of freeze-dried meat and oilseed samples was found to be comparable to values derived from Soxhlet-extracted samples (26). Besides, only small amounts of residual lipids could be recovered by an additional extraction of the SFE-extracted matrix by the Bligh and Dyer solvent extraction procedure. As far as the minor constituents are concerned, it was found that the extraction recovery ranged from 99% for PC to 88% for PA. Hence, Snyder et al. concluded that SFE can be used as a rapid, automated method to obtain total fat, including total phospholipids, from foods (26). 

Phylloquinone has been extracted from powdered infant formula using supercritical carbon dioxide at 8000 psi and 60°C for 15 min (65). The extracted material was readily recovered by depressurization of the carbon dioxide across an adsorbent trap and then washed from the trap with a small volume of dichloromethane/acetone (1 + 1) to give a sample suitable for direct HPLC analysis. Trial experiments gave recoveries of 92% of phylloquinone from a Chro-mosorb W matrix. A similar technique was applied to the extraction of retinyl palmitate from cereal products (90). 

Karasek, P, J. Pol, J. Planeta, et al. 2002. Partition coefficients of environmentally important phenols in a supercritical carbon dioxide-water system from concurrent extraction without analysis of the compressible phase. Anal. Chem. 74 4294-4297. 

Analysis of clove bud oil extracted with liquid and supercritical carbon dioxide showed significant qualitative and quantitative compositional differences compared to oil obtained by the conventional hydrodistillation process. The parameters such... 

Supercritical fluid extraction (SFE) is a suitable process for many separation problems. The regeneration of the supercritical fluid is as important as the extraction step itself Therefore this paper presents a method to do this in a more isobaric way than the customary pressure reduction regeneration. For the example of soil remediation we have investigated the activated carbon regeneration of supercritical carbon dioxide loaded with the low-volatile polycyclic aromatic hydrocarbon (PAH) pyrene. Characteristics of supercritical fluid extraction for soil remediation are elevated temperatures and pressures up to 370 K and 300 bar. For this reason adsorption isotherms of pyrene on activated carbon up to these conditions are measured first. Subsequently this method is used to regenerate carbon dioxide in a closed solvent cycle plant with a 4 1 extractor. An economic analysis using these results indicate that the soil remediation costs will decrease for about 20 - 30 % by means of an activated carbon adsorber. 

As an alternative to traditional solvent extraction methods, the extraction by supercritical (SC) fluids has been used in tocol analysis. This is an environmentally friendly technique as little or no solvents are used. Extraction parameters, e.g. temperature and fluid density, are easily optimized and managed, and as the extraction is fast it is thus suitable for routine work with many samples. SC carbon dioxide has been used to extract tocols from barley (Fratianni et al, 2002), dried bay leaves (Gomez-Coronado et al, 2004), and garden cress seeds (Diwakar et al, 2010). Extractions were carried out in single or multiple steps and with different fluid densities controlled by extraction pressures. Tocol yields from barley were 5% and 14% less than by Soxhlet and chloroform-methanol extractions (Fratianni et al, 2002), yields from garden cress seeds were 26% less than by Soxhlet extraction (Diwakar et al, 2010), and a- and y-tocopherol yields from dried bay leaves were 22% and 40% less than by acetone extraction (Gomez-Coronado et al, 2004). Despite lower recoveries of tocols, the SC carbon dioxide extraction methods were considered comparable to the classical extraction methods (Fratianni et al, 2002). 

A detailed description of the experimental apparatus and procedure used for the aqueous study are given elsewhere (Roop and Akgerman, Ind. Eng. Chem. R., in review) Static equilibrium extractions were carried out in a high pressure equilibrium cell (300 mL Autoclave). After the vessel is initially charged with 150 mL of water containing 6.8 wt.% phenol and supercritical carbon dioxide (and a small amount of entrainer, if desired), the contents were mixed for one hour followed by a two hour period for phase separation. Samples from both the aqueous phase and the supercritical phase were taken for analysis and the distribution coefficient for phenol calculated. 

Bristow SC, Shekunov BY, York P. Solubility analysis of drug compounds in supercritical carbon dioxide using static and dynamic extraction systems. Ind Eng Chem Res 2001 40 1732-1739. 

By 1985 the SCF community had developed and accumulated substantial combined knowledge in fundamental behavior, application, and production. But when this paper was published, it resulted in some discussion and confusion within the community. It was our opinion at that time that the sodium salt of p-nitrophenyl phosphoric acid could not dissolve in supercritical carbon dioxide, and this opinion was later confirmed in tests on the solubility of the sodium salt of p-nitrophenyl phosphoric acid. Krukonis and Hammond carried out tests to measure the solubility of the salt in dry carbon dioxide and to investigate if there could be some cosolvent effect of water in water-saturated carbon dioxide. They found that the solubility was virtually nil, i.e., the salt could not be detected by UV analysis of the extracts in the collection vessel, and there was no visible extract. On the basis of the insolubility of the salt in dry or wet carbon dioxide from the solubility tests, the authors... 

Analysis of process development data - The following illustrates how PDU data can be used to develop a commercial SCFCO2 plant s process design. This data is provided by Marc Sims on pyrethrins, a natural insecticide extracted with subcritical and supercritical carbon dioxide from pyrethrum flowers (a species of chrysanthemum). 

Supercritical fluid extraction (SEE) using supercritical carbon dioxide (SC-CO2) has been successfully used for isolation of volatile nitrosamines from different matrices such as tobacco and food products. This technique presents several advantages with respect to other extraction methods (e.g., mineral oil distillation or low-temperature vacuum distillation) currently used. Thus, SEE minimizes sample handling, provides fairly clean extracts, expedites sample preparation, and reduces the use of environmentally toxic solvents. Good results have also been obtained with the use of SPE in the analysis of food matrices combining extraction with Extrelut sorbent and purification with Florisil. This method is applicable for the analysis of a range of the most widely encountered volatile N-nitrosamines, including the poorly volatile NDBA, NDBzA, and N-nitroso-N-methylaniline in various food products. Active carbon is suitable for this preconcentration step due its low cost, versatility, and easy application. 

Bilia AR, Bergonzi MC, Mazzi G, and Vincieri FF (2002) Analysis of plant complex matrices by use of nuclear magnetic resonance spectroscopy supercritical carbon dioxide arnica extract Journal of Pharmaceutical and Biomedical Analysis 30 321-330. 

---