| 1. |
- Abrahamsson, Victor, et al.
(författare)
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Determination of carotenoids in microalgae using supercritical fluid extraction and chromatography.
- 2012
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Ingår i: Journal of chromatography. A. - : Elsevier BV. - 1873-3778 .- 0021-9673. ; 1250, s. 63-68
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Tidskriftsartikel (refereegranskat)abstract
- A method was developed based on supercritical fluid chromatography for quantitative determination of carotenoids in extracts of Scenedesmus sp. By utilizing the low backpressure in supercritical fluid chromatography, a C18 column and a 2-ethyl pyridine column were coupled in series. It was concluded that even minor changes in temperature had a substantial effect on selectivity. A standard mixture of 8 carotenoids and microalgae extracts obtained through supercritical fluid extraction with and without 10% ethanol as a co-solvent were successfully separated. All of the carotenoids were separated within 10min, while the total analysis time was 20min. The method was validated and the carotenoids of microalgae extracts were quantified. Furthermore, the method should be seen as a more rapid and environmentally sustainable alternative to traditional high-performance liquid chromatography methods utilizing organic solvents.
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| 2. |
- Abrahamsson, Victor, et al.
(författare)
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Supercritical fluid extraction of lipids from linseed with on-line evaporative light scattering detection.
- 2015
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Ingår i: Analytica Chimica Acta. - : Elsevier BV. - 1873-4324 .- 0003-2670. ; 853, s. 320-327
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Tidskriftsartikel (refereegranskat)abstract
- Supercritical fluid extraction (SFE) is a green alternative method of extraction for neutral lipids in seeds compared to conventional methods utilizing organic solvents. In this work, a novel method where SFE is hyphenated with an evaporative light scattering detector is presented. The method was subsequently applied to determine lipid content in crushed linseed. The new method enables rapid quantification of extracted lipids as well as be ability to continuously monitor the extraction rate in real-time, thus being able to determine the time point of completed extraction. Both the detector and the method was validated. The results show that any of several tested oils can be used to calibrate the detection method for the determination of lipids extraction from linseed. The overall method repeatability and intermediate precision was 2.6% relative standard deviations. The extracted amount was significantly less than that obtained using the standard method of Soxhlet with petroleum ether, 26.0±0.4% (95% CI, n=9) compared to 32.3±1.3% (95% CI, n=3) of extracted amounts. It was found that channeling effects were present, and by either performing sequential repeated extractions with decompression in-between or by using a relatively large vessel a more complete extraction could be obtained. Interestingly, a substantially higher extracted amount (approximately 50%) was obtained compared to both a single extraction by SFE and the Soxhlet method. Therefore, it is recommended that an additional extraction including a rapid decompression in-between should be included in the validation of a method using supercritical fluid extraction, in order to either rule out channeling effects or to acquire a full recovery.
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| 3. |
- Andersson, J. M., et al.
(författare)
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Pressurised hot water extraction with on-line particle formation by supercritical fluid technology
- 2012
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Ingår i: Food Chemistry. - : Elsevier BV. - 1873-7072 .- 0308-8146. ; 134:4, s. 1724-1731
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Tidskriftsartikel (refereegranskat)abstract
- In this work, an on-line process for pressurised hot water extraction (PHWE) of antioxidants from plants as well as drying of the extract in one step by particle formation based on the use of supercritical carbon dioxide (SC-CO2) has been developed. This process has been called WEPO (R), water extraction and particle formation on-line. With this process, dried extracts from onion with the same composition of quercetin derivatives as non-dried extracts have been obtained as a fine powder with spherical particles from 250 nm to 4 mu m in diameter. The major compounds present in the extract were quercetin-3,4'-diglucoside, quercetin-4'-glucoside and quercetin. An auxiliary inert gas (hot N-2) was used to enhance the drying process. Parameters such as temperature (120 degrees C), SC-CO2 and N-2 pressures (80 and 12.5 bar, respectively) and flow rate of SC-CO2 (10 ml/min), have been settled by trial-and-error in order to achieve a fine and constant spray formation. Water content, size and morphology, antioxidant capacity and quercetin content of the particles were studied to evaluate the efficiency of the WEPO process. Results were compared with the ones from extracts obtained by continuous flow PHWE followed by freeze-drying. Results showed that both processes gave similar results in terms of antioxidant capacity, concentration of quercetin derivatives and water content, while only WEPO was able to produce defined spherical particles smaller than 4 mu m. (C) 2012 Elsevier Ltd. All rights reserved.
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| 4. |
- Andersson, Martin, et al.
(författare)
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Dynamic pH determination at high pressure of aqueous additive mixtures in contact with dense CO2
- 2018
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Ingår i: Journal of Supercritical Fluids. - : Elsevier BV. - 0896-8446 .- 1872-8162. ; 136, s. 95-101
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Tidskriftsartikel (refereegranskat)abstract
- A system consisting of a high-pressure tolerant microfluidic glass chip, high-speed absorbance imaging, and image processing has been developed to study rapid dynamic events like pH change in a multiphase flow. The system gives both kinetic and quantitative equilibrated information. By tracking the interactions of aqueous additive mixtures and liquid CO2, at 80 bar and 24 °C, under flow, measurement at a given P, T condition is done in 0.25 s. The acidification rate to steady state was found to be mass transport limited, occurring in less than 1 s. For 30 mM of the additives ammonium acetate and ammonium formate, equilibrium pH of 4.5 and 4.1, respectively, was seen. These additives are of key importance in common mobile phases used in SFC.
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| 5. |
- Cui, Jingwen, et al.
(författare)
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Extraction with Water-in-Carbon Dioxide Microemulsions : A Case Study on Steviol Glycosides
- 2019
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Ingår i: Journal of Surfactants and Detergents. - : Wiley. - 1097-3958 .- 1558-9293. ; 22:6, s. 1505-1514
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Tidskriftsartikel (refereegranskat)abstract
- This work explores the use of water-in-supercritical carbon dioxide (scCO2) microemulsions for the extraction of polar metabolites from plants. Stevia rebaudiana Bertoni leaves and polyethylene glycol trimethylnonyl ether (TMN) surfactants were selected for a case study. A CO2-water-TMN 10 mixture at 35 °C and 30.0 MPa extracted 7 mg target analyte/g dry leaves. The extraction was proven to occur due to a water-surfactant liquid solution rather than a water-in-CO2 microemulsion. Using a modified extraction setup, the microemulsion was created prior to extraction. TMN 6 was able to dissolve enough water in CO2 to extract steviol glycosides, in detectable but very small amounts.
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| 6. |
- Ejenstam, Lina, et al.
(författare)
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The effect of superhydrophobic wetting state on corrosion protection : The AKD example
- 2013
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Ingår i: Journal of Colloid and Interface Science. - : Elsevier BV. - 0021-9797 .- 1095-7103. ; 412, s. 56-64
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Tidskriftsartikel (refereegranskat)abstract
- Corrosion is of considerable concern whenever metal is used as construction material. In this study we address whether superhydrophobic coatings could be used as part of an environmentally friendly corrosion-protective system, and specific focus is put on how the wetting regime of a superhydrophobic coating affects corrosion inhibition. Superhydrophobic alkyl ketene dimer (AKD) wax coatings were produced, using different methods resulting in hierarchical structures, where the coatings exhibit the same surface chemistry but different wetting regimes. Contact angle measurements, ESEM, confocal Raman microscopy, open circuit potential and electrochemical impedance spectroscopy were used to evaluate the surfaces. Remarkably high impedance values of 1010Ωcm2 (at 10-2Hz) were reached for the sample showing superhydrophobic lotus-like wetting. Simultaneous open circuit potential measurements suggest that the circuit is broken, most likely due to the formation of a thin air layer at the coating-water interface that inhibits ion transport from the electrolyte to the metal substrate. The remaining samples, showing superhydrophobic wetting in the rose state and hydrophobic Wenzel-like wetting, showed less promising corrosion-protective properties. Due to the absence of air films on these surfaces the coatings were penetrated by the electrolyte, which allowed the corrosion reaction to proceed.
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| 7. |
- Gil-Ramirez, Alicia, et al.
(författare)
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Data on saponins, xylan and cellulose yield obtained from quinoa stalks after pressurized hot water extraction
- 2018
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Ingår i: Data in Brief. - : Elsevier BV. - 2352-3409. ; 20, s. 289-292
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Tidskriftsartikel (refereegranskat)abstract
- The data we present below are linked to our research paper “Integrated process for sequential extraction of saponins, xylan and cellulose from quinoa stalks (Chenopodium quinoa Willd.)” (Gil-Ramírez et al., 2018) [1]. The objective is to provide supplementary information in order to facilitate the comprehension of the central composite experimental design (rotatable 22) used in the integrated process of extractions. Two factors, temperature and time of extraction are considered in the design. The responses are the yield of saponin, xylan and cellulose. First, the desirable linear regression obtained by the observed vs. predicted yields plot for each variable response confirm the validation of the model (Fig. 1). Second, the data presented here through Standardized Pareto Charts (Fig. 2), provides information about the effect of the time and temperature, as well as their interactions, in the yield of saponins, xylan and cellulose obtained in an integrated sequential extraction.
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| 8. |
- Gil-Ramirez, Alicia, et al.
(författare)
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Efficient methodology for the extraction and analysis of lipids from porcine pulmonary artery by supercritical fluid chromatography coupled to mass spectrometry
- 2019
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Ingår i: Journal of Chromatography A. - : Elsevier BV. - 0021-9673. ; 1592, s. 173-182
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Tidskriftsartikel (refereegranskat)abstract
- Pulmonary artery grafts are needed as cardiovascular bioprosthetics. For successful tissue recellularization after transplantation, lipids have to be removed from the donor artery. Developing a selective process to remove lipids without damaging the extracellular matrix greatly depends on knowing the amount and type of lipid compounds in the specific tissue. Here we present an efficient methodology for the study of lipids present in porcine pulmonary arteries. The performance of six extraction methods to recover lipids from artery was evaluated. For this purpose, a supercritical fluid chromatography method coupled to quadrupole time-of-flight mass spectrometry detection (UHPSFC/QTOF-MS) was adapted. The method enabled separation of lipids of a wide range of polarity according to lipid class in less than 7 min. One dichloromethane-based extraction method was shown to be the most efficient one for the recovery of lipids from pulmonary artery. However, one MTBE-based extraction method was able to show the highest fatty acid extraction yields (to the expense of longer extraction times). Lipids were relative quantified according to class, and the major species within each class were identified. Triacylglycerols and glycerophospholipids were the most abundant classes, followed by sphingomyelins, monoacylglycerols and fatty acyls. The matrix effect exerted no interference on the analytical method, except for some few combinations of extraction method and lipid class. These results are of relevance for lipidomic studies from solid tissue, in particular for studies on pulmonary and cardiovascular diseases. Finally, our work sets the basis for the further development of a selective processes to remove lipids from pulmonary artery without damaging the tissue prior to transplantation.
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| 9. |
- Gil-Ramírez, Alicia, et al.
(författare)
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Pressurized carbon dioxide as a potential tool for decellularization of pulmonary arteries for transplant purposes
- 2020
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- Vascular bio-scaffolds produced from decellularized tissue offer a promising material for treatment of several types of cardiovascular diseases. These materials have the potential to maintain the functional properties of the extracellular matrix (ECM), and allow for growth and remodeling in vivo. The most commonly used methods for decellularization are based on chemicals and enzymes combinations, which often damage the ECM and cause cytotoxic effects in vivo. Mild methods involving pressurized CO2-ethanol (EtOH)-based fluids, in a supercritical or near supercritical state, have been studied for decellularization of cardiovascular tissue, but results are controversial. Moreover, data are lacking on the amount and type of lipids remaining in the tissue. Here we show that pressurized CO2-EtOH-H2O fluids (average molar composition, ΧCO2 0.91) yielded close to complete removal of lipids from porcine pulmonary arteries, including a notably decrease of pro-inflammatory fatty acids. Pressurized CO2-limonene fluids (ΧCO2 0.88) and neat supercritical CO2 (scCO2) achieved the removal of 90% of triacylglycerides. Moreover, treatment of tissue with pressurized CO2-limonene followed by enzyme treatment, resulted in efficient DNA removal. The structure of elastic fibers was preserved after pressurized treatment, regardless solvent composition. In conclusion, pressurized CO2-ethanol fluids offer an efficient tool for delipidation in bio-scaffold production, while pressurized CO2-limonene fluids facilitate subsequent enzymatic removal of DNA.
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| 10. |
- Gil-Ramírez, Alicia, et al.
(författare)
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Purification of Natural Products by Selective Precipitation Using Supercritical/Gas Antisolvent Techniques (SAS/GAS)
- 2021
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Ingår i: Separation and Purification Reviews. - : Informa UK Limited. - 1542-2119 .- 1542-2127. ; 50:1, s. 32-52
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Forskningsöversikt (refereegranskat)abstract
- Supercritical fluids offer considerable advantages for the isolation of natural products. Supercritical fluids can be used as antisolvents to precipitate selectively target compounds from a mixture and to remove impurities by the Supercritical Antisolvent technique (SAS). The present decade has experienced a considerable increase in the number of publications that apply this technique to natural extracts, especially for the isolation of polyphenols and carotenoids from plants and microalgae. However, the lack of a clear terminology and purpose adds confusion to the topic. The proposed review aims at defining a research field that consists in applying SAS to natural extracts for the purification of target compounds. To do so, we trace back the origin of the field, discuss the different terminology used to refer to such processes, and suggest appropriate terms for the process and for reported results. This work explores the scope of the topic by compiling all works published to date from a scattered literature, using all possible process terminologies for the search. The information given aims to highlight the most promising applications explored so far and possibly inspire further research.
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