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Notes Bull. Korean Chem. Soc. 2014, Vol. 35, No. 10 3109 ODS2 (4.6 × 150 mm, 5 μm particle size) column. An aliquot of 10 μL was injected into the HPLC system. The mobile phase was a mixture of 30% of methanol and 70% of water. The flow rate was 0.8 mL/min, and UV detector operating at 424 nm. A typical HPLC chromatogram is shown in Figure 3. Results and Discussion SFE conditions for the optimization of the extraction of curcumins from a curry powder were evaluated. The amounts of extracted curcumins were quantitatively measured by HPLC analysis described in the earlier section. Effect of Pressure on Extraction Efficiency. It is important to find the optimum SFE operating conditions which would result in the most efficient extraction of curcumins from a curry powder. In particular, the pressure and temperature of supercritical fluid, which are the most important parameters to be optimized, for the efficient SFE experiment. Extraction efficiency of curcumins was investigated as a function of extraction pressure (Table 1). Extraction pressures of 200, 225, 250 and 275 atm were chosen. The pressure of the supercritical fluid plays an important role in the SFE of curcumins from a curry powder. An increase in pressure causes an increase in the fluid density, and thus it results in the increase in the solvating power of the supercritical fluid. As shown in Table 1, the extraction efficiency increases with increasing pressure of extracting fluid until the pressure reaches 250 atm. At higher pressure than 250 atm, the extraction efficiency decreases because extraction of curcumins can be competed with extraction of other compounds in the sample matrix. Therefore, the optimized pressure was chosen as 250 atm for Table 1. Supercritical fluid extraction of curcumins using various pressures the extraction of curcumins from a curry powder. Effect of Temperature on Extraction Efficiency. To find the optimum extraction temperature, the temperature of the extraction vessel was varied from 40 oC to 70 oC, under the pressure of 250 atm (Table 2). As shown in Table 2, the best extraction efficiency was obtained at the temperature of 60 oC. From 40 oC to 60 oC. increased temperature resulted in increased extraction efficiency of curcumins. At higher temperature, curcumins become more volatile and can be easily separated from the matrix. However, at the fairly high temperature (70 oC), the extraction efficiency of curcumins was decreased due to the decreased density of supercritical fluid. Effect of Modifier on Extraction Efficiency. The effect of modifier on the extraction efficiency of curcumins is shown in in Table 3. The modifier used in this study was ethanol which is known as the most effective modifier for the SFE of curcumins.8 As can be seen in Table 3, the poor extraction result (4.53 mg/g) with neat supercritical CO2 was obtained. This result is probably caused by the fact that curcumins consisit of polar fuctional groups, i.e. phenol and ketone. The use of modifier can have a profound effect on increasing the solubility levels of polar solutes in super- critical fluids. When the flow rate of modifier was increased from 0.1 mL/min to 0.3 mL/min, the extraction yield of curcumins increased from 14.29 mg/g to 31.07 mg/g. But at higher flow rate of modifier (0.4 mL/min), the extraction yield of curcumins was decreased. The decreased extraction of curcumins with 0.4 mL/min flow rate of modifier may be attributed to some solute-modifier interactions that can weaken the solute-supercritical CO2 interactions. Similar results were obtained for other samples and matrices using Table 3. Supercritical fluid extraction of curcumins using different flow rates of ethanol as a modifier Pressure, atm 275 250 225 200 The amount of extracted total curcumins (mg/g) 4.15 ± 0.4 4.53 ± 0.3 3.68 ± 0.3 2.55 ± 0.3 Flow rate of modifier none 0.1 mL/min 0.2 mL/min 0.3 mL/min 0.4 mL/min The amount of extracted total curcumins (mg/g) 4.53 ± 0.3 14.29 ± 0.5 21.58 ± 0.5 31.07 ± 0.6 21.78 ± 0.6 Experimental condition: 120 min extraction at 40 °C, CO2 flow 3.0 mL/ min. RSDs based on triplicate extractions under each condition. Table 2. Supercritical fluid extraction of curcumins using various temperatures Experimental condition: 120 min extraction at 60 °C and 250 atm, CO2 flow 3.0 mL/min. RSDs based on triplicate extractions under each condition. Table 4. Supercritical fluid extraction of curcumins using various extraction times Temperature, °C 70 60 50 40 The amount of extracted total curcumins (mg/g) 7.26 ± 0.4 8.04 ± 0.5 4.68 ± 0.4 4.53 ± 0.3 Extraction time, min 90 120 150 The amount of extracted total curcumins (mg/g) 26.45 ± 0.5 31.07 ± 0.6 31.14 ± 0.6 Experimental condition: 120 min extraction at 250 atm, CO2 flow 3.0 mL/min. RSDs based on triplicate extractions under each condition. Experimental condition: Supercritical fluid extraction with a ethanol modified CO2 fluid (3.0 mL/min CO2 + 0.3 mL/min ethanol) at 60 oC and 250 atm. RSDs based on triplicate extractions under each condition.PDF Image | Rapid and Efficient Extraction of Curcumins SCO2
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