Capillary supercritical fluid extract

ON-LINE COUPLING OF SUPERCRITICAL FLUID EXTRACTION WITH CAPILLARY ELECTRODRIVEN SEPARATION TECHNIQUES (SFE-CESTs)... 

H. Daimon and Y. Hirata, Direct coupling of capillary supercritical fluid chromatography with superaitical fluid extraction using modified carbon dioxide , J. High Resolut. Chromatogr. 17 809-813 (1994). 

Kuitunen ML, Hartonen K, Riekkoa ML. 1991. Analysis of chemical warfare agents in soil samples by off-line supercritical fluid extraction and capillary gas chromatography. Journal of Microcolumn Separation 3(6) 505-512. 

CZE = capillary zone electrophoresis EC = electrochemical detector GC = gas chromatography HCD = Hall conductivity detector HPLC = high performance liquid chromatography IDMS = isotope dilution mass spectrometry MS = mass spectrometry RSD = relative standard deviation SEE = supercritical fluid extraction SPE = solid phase extraction UV = ultraviolet absorbance detection... 

Artemisinin 9a has been extracted from Artemisia annua L. by supercritical fluid extraction and analyzed by supercritical fluid chromatography (SFC) using a capillary column coupled with a flame ionization detector <1997JCFI(A)353>. The SFC method has also been used for the determination of artemisinin in whole blood <1995JCH(B)183>. 

Figure 28-14a shows how a supercritical fluid extraction can be carried out. Pressurized fluid is pumped through a heated extraction vessel. Fluid can be left in contact with the sample for some time or it can be pumped through continuously. At the outlet of the extraction vessel, the fluid flows through a capillary tube to release pressure. Exiting C02 evaporates, leaving extracted analyte in the collection vessel. Alternatively, the C02 can be bubbled through a solvent in the collection vessel to leave a solution of analyte. 

X. Lou, H.-G. Janssen and C. A. Cramers, Investigation of parameters affecting the online combination of supercritical fluid extraction with capillary gas chromatography , J. Chromatogr. 750 215-226 (1996). 

F. M. Lanfas and M. A. Ruggiero, On-line coupling of supercritical fluid extraction to capillary column electrodriven separation techniques , J. Microcolumn Sep. 12 61-67 (2000). 

The method of analysis involves extraction of 1 L of aqueous sample (liquid-liquid extraction) or 25 g of soil (sonication or Soxhlett extraction or supercritical fluid extraction) or an appropriate amount of the sample with methylene chloride. The extract is dried, concentrated to a volume of 1 mL, and injected into a capillary GC column for separation and detection by FID. For quantitation, the area or height response of all peaks eluting between C-10 and C-28 are summed and compared against the chromatographic response of the same peaks in a 2 Fuel or Diesel Oil standard. A 10-component n-alkanes mixture containing even numbered alkanes ranging between 10 and 28 C atoms has been recommended as an alternative calibration standard. These alkanes occur in all types of diesel oils, and each compound constitutes approximately a 1% total mass of diesel fuel, i.e., 1 g of diesel fuel contains about 10 mg each of any of the above alkanes. Therefore, when using the latter as a calibration standard, the result must be multiplied appropriately by 100. 

The techniques used were based on solvent extraction (e.g. with pentane), complexation (e.g. with diethyldithiocarbamate, EDTA), derivatisation (e.g. hydride generation, propylation or ethylation), and capillary GC separation followed by a range of detection techniques (e.g. QFAAS, ICPMS, MIP-AES, MS) DPASV has also been successfully used. In the frame of this project, two new techniques were also developed and successfully applied, namely supercritical fluid extraction followed by CGC/MS and isotope dilution ICPMS after ethylation and CGC separation. A full description of the techniques is given elsewhere (Quevauviller, 1998b). 

Alexandrou N, Miao Z, Colquhoun M, et al. 1992. Supercritical fluid extraction and cleanup with capillary GC-ion trap mass spectrometry for determination of polychlorinated dibenzo-p-dioxins and dibenzofurans in environemental samples. J Chromatogr Sci 30(9) 335-382. 

Heaton et al. have reported the supercritical fluid chromatography of taxicin I and taxicin II extracted by supercritical fluid extraction of Taxu baccata, the English yew tree [41]. They compared capillary- and packed- column SFC and concluded that packed-column SFC was better than capil4 lary-column SFC for quantitative analysis of these compounds. Capillary SFC was done on either a biphenyl or carbowax column with unmodified carbon dioxide as the mobile phase. The packed-column SFC was performed on a nitrile column with a mobile phase consisting of a methanol gradient with carbon dioxide. 

Figure 7.17 Capillary supercritical fluid chromatograms of ginseng extract. (1) Methyltestosterone (internal standard), (2) panaxadiol, (3) panaxatriol. [Reprinted from Ref. 28, Biomedical Chrom. (1992) with kind permission of John Wiley and Sons, Ltd., UK.]...

P. Edder, W. Haerdi, I. Veuthey, and C. Staub, Quantitative capillary supercritical fluid chromatography and supercritical fluid extraction of basic drugs of abuse, Chimia, 46 141 (1992). 

While it is wonderful to be able to inject neat samples directly, sample preparation can often improve selectivity and sensitivity. If the resolution is poor, the salt content of the sample too high, or the capillary fouls, consider a sample cleanup. This can include liquid-liquid extraction, solid-phase extraction, supercritical fluid extraction, protein precipitation, or dialysis, depending on the solutes and application [38]. The final sample diluent should be a solution that is CE-Mendly. That usually means low ionic strength compared to the BGE. 

Supercritical fluid extraction coupled to SFC has been used for the extraction, separation and identification of PAHs from coal. The supercritical extract was expanded with the aid of a frit restrictor accommodated in the sample cavity of a cooled micro-injector, the analytes being deposited by condensation while CO, was sent to waste through a vent valve. Subsequently, the loop contents were connected on-line to the mobile phase of the capillary chromatograph. The extracted analytes were detected by off-line FTIR spectroscopy following collection on a KBr disc and evaporation of the solvent [104]. 

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