Countercurrent packed column supercritical CO2 extraction of olive oil. Mass transfer evaluation

Approaches for application of sub and supercritical fluid extraction for quantification of orbifloxacin from plasma and milk: application to disposition kinetics

Since its extensive development in the early 1980s, SFE has attracted considerable attention as a sample-preparation procedure. However, other different sample preparation procedures, including precipitation, liquid- and/or solid-phase extraction in biological fluids, also remain in use. In this investigation, SFE was introduced to isolate and identify orbifloxacin from plasma and milk. Four parameters, including the temperature and the pressure of supercritical fluid, modifier ratios, and dynamic extraction time, were evaluated and optimized to obtain the best yield of the analyte from the biological fluids. Determinations of the orbifloxacin (OBFX) in the extracts were carried out using HPLC-FLD. The optimum conditions of the extraction process that yielded the maximum analyte extraction efficiencies were 150 degrees C vs. 60 degrees C, 250 kg cm(-2), 30% vs. 35% methanol, and 40 min vs. 20 min, for plasma and milk, respectively. The linearity of the calibration curves as well as the instrument LODs/LOQs were evaluated. Good linearity (at least r(2) > or = 0.999) of the calibration curves was obtained over the range from 0.2 to 0.01 microg mL(-1). The method showed a good recovery rate (74.2-127.73%) and precision (RSDs: 1.64-20%). The instrumental LOD and LOQ values were 0.004 microg mL(-1) vs. 0.01 microg mL(-1) or 0.006 microg mL(-1) vs. 0.02 microg mL(-1), for plasma and milk, respectively. The method was successfully applied to estimate the pharmacokinetic variables of orbifloxacin in lactating does. To the best of our knowledge, this is the first time that SFE has been applied to isolate an antimicrobial agent from biological fluids. This method is promising for clinical applications and for pharmacokinetic studies of various pharmaceuticals in biological fluids.

Supercritical carbon dioxide extraction of astaxanthin from Haematococcus pluvialis with vegetable oils as co-solvent

Soybean oil and olive oil were investigated as continuous co-solvents for supercritical carbon dioxide (SC-CO(2)) extraction of astaxanthin from Haematococcus pluvialis. Without co-solvents, only 25.40+/-0.79% efficiency was achieved with SC-CO(2) extraction at 70 degrees C and 40 MPa at a continuous flow rate of 3 mL min(-1) for 5h. In the presence of soybean oil or olive oil as a co-solvent, the extraction efficiency was enhanced, with the most appropriate level of soybean oil in the solvent mixture being 10% by volume. At this concentration and the above extraction conditions, the highest extraction efficiency of 36.36+/-0.79% was obtained for soybean oil, a 30% increase in extraction efficiency compared with SC-CO(2) extraction without soybean oil, whereas the 10% olive oil increased the extraction efficiency further to 51.03+/-1.08%, which was comparable to that obtained using ethanol as co-solvent.

Use of compressed fluids for sample preparation: Food applications

This review attempts to provide an updated overview (including works published till June 2006) on the latest applications of compressed fluids as sample preparation techniques for food analysis. After a general review of the principles of supercritical fluid extraction (SFE) and pressurized liquid extraction (PLE; also called accelerated solvent extraction, ASE or subcritical water extraction, SWE, when water is employed as extraction solvent), the principal applications of such techniques in the mentioned fields of food and natural products are described, discussing their main advantages and drawbacks.

Identification of beta-sitosterol, stigmasterol and ergosterin in A. roxburghii using supercritical fluid extraction followed by liquid chromatography/atmospheric pressure chemical ionization ion trap mass spectrometry

beta-Sitosterol and stigmasterol are the most common phytosterols in traditional Chinese medicine. They have been proved to have many important bioactivities. To the best of our knowledge, this is the first report that beta-sitosterol, stigmasterol and ergosterol coexisting in A. roxburghii herbs can be simultaneously extracted by a supercritical fluid extraction (SFE) procedure; then a simple high-performance liquid chromatography/atmospheric pressure chemical ionization ion trap mass spectrometry (HPLC/APCI/MS) method was developed for simultaneous identification and determination of these three compounds. The ion trap MS/MS detector was equipped with an atmospheric pressure chemical ionization source operating in the positive ion mode, APCI(+). The linear responses were obtained in the concentration range of 0.50-150 microg/mL (r = 0.9999) for ergosterol, 5-400 microg/mL (r = 0.9999) for stigmasterol, and 10-2000 microg/mL (r = 0.9998) for beta-sitosterol. An orthogonal L(9) (3(3)) test design was employed for optimization of the SFE process. Under the optimized conditions, i.e. pressure of 25 mPa, temperature of 45 degrees C and ethanol as modifier, the concentrations of sterols in the extract were found to be 2.89% (g/g) for beta-sitosterol, 3.56% (g/g) for stigmasterol and 2.96% (g/g) for ergosterin. The SFE method was also compared with a previously developed Soxhlet extraction. The SFE method produced higher yields of sterols than that of the Soxhlet extraction. The proposed method has been successfully used for identification and quantitation of beta-sitosterol, stigmasterol and ergosterin in a real A. roxburghii sample.