2.1. Microalgae
The microalgae used for the experiment was kindly provided by Solix BioSystems (Solix BioSystems
Inc., USA). The microalgae strain used for this study was Botryococcus braunii
2.2. Conventional solvent extraction
Protocols used for solvent extraction were based on those reported by Bligh and Dyer [25]. The
solvent used was a mixture of 2:1 chloroform and methanol. Dried algae samples of approximately 5g mass were mixed with 100mL of solvent and soaked overnight. Solids were removed by filtration and the solvent extract was mixed with ~ 50 mL 0.9% NaCl in a separator funnel and allowed to stand overnight.After separation of the organic phase from brine, the solvent was removed by rotary evaporator. Four replicates of each solvent system were evaluated and the results averaged. Lipid percentage was determined by comparing the extracted algal oil mass to initial dried sample mass.
2.3. Supercritical fluid extraction
Carbon dioxide was supplied with a purity of 99.995% from Linde Gases LTDA. Supercritical carbon
dioxide extractions were performed at the temperature range 50 – 85ºC and pressures range of
200 – 250 bar. These extraction conditions were chosen taking into account previous work reported for the extraction of lipids from other microalgae [26-28].
2.4. Fatty acid analysis
Lipid extracts were transmethylated with methanol-acethyl chloride, as described by Lepage and Roy[29], in the presence of an appropriate amount of heptadecanoic acid as an internal standard. The methylester were then analyzed on a 7890 Agilent gas chromatograph (GC), equipped with a flame ionization detector. Separation was carried out on 0.32 mm x 30 m fused silica capillary column (0.32 μm filmthickness) Sulpelcowax 10 (Supelco, Bellafonte PA, USA) with helium as carrier gas at a flow rate of 3.5 ml/min. The column temperature was programmed at an initial temperature of 200ºC for 8 min, then increased at 4ºC/min to 240ºC and held there for 8 min. Injector and detector temperatures were 250 and 280ºC, respectively and split ratio was 1:50. FAMEs were identified and their response factors calculated by comparing peak areas of known quantities of authentic standards (Supelco) to the internal standard,heptadecanoic acid. Averages of duplicate injections were reported.
2.1. MicroalgaeThe microalgae used for the experiment was kindly provided by Solix BioSystems (Solix BioSystemsInc., USA). The microalgae strain used for this study was Botryococcus braunii2.2. Conventional solvent extractionProtocols used for solvent extraction were based on those reported by Bligh and Dyer [25]. Thesolvent used was a mixture of 2:1 chloroform and methanol. Dried algae samples of approximately 5g mass were mixed with 100mL of solvent and soaked overnight. Solids were removed by filtration and the solvent extract was mixed with ~ 50 mL 0.9% NaCl in a separator funnel and allowed to stand overnight.After separation of the organic phase from brine, the solvent was removed by rotary evaporator. Four replicates of each solvent system were evaluated and the results averaged. Lipid percentage was determined by comparing the extracted algal oil mass to initial dried sample mass.2.3. Supercritical fluid extractionCarbon dioxide was supplied with a purity of 99.995% from Linde Gases LTDA. Supercritical carbondioxide extractions were performed at the temperature range 50 – 85ºC and pressures range of 200 – 250 bar. These extraction conditions were chosen taking into account previous work reported for the extraction of lipids from other microalgae [26-28].2.4. Fatty acid analysisLipid extracts were transmethylated with methanol-acethyl chloride, as described by Lepage and Roy[29], in the presence of an appropriate amount of heptadecanoic acid as an internal standard. The methylester were then analyzed on a 7890 Agilent gas chromatograph (GC), equipped with a flame ionization detector. Separation was carried out on 0.32 mm x 30 m fused silica capillary column (0.32 μm filmthickness) Sulpelcowax 10 (Supelco, Bellafonte PA, USA) with helium as carrier gas at a flow rate of 3.5 ml/min. The column temperature was programmed at an initial temperature of 200ºC for 8 min, then increased at 4ºC/min to 240ºC and held there for 8 min. Injector and detector temperatures were 250 and 280ºC, respectively and split ratio was 1:50. FAMEs were identified and their response factors calculated by comparing peak areas of known quantities of authentic standards (Supelco) to the internal standard,heptadecanoic acid. Averages of duplicate injections were reported.
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