The influence of pressure and temperature on the solubility of supercritical carbon dioxide to extract insecticidal components from Pelargonium radula leaves: article

Pelargonium radula (P. radula) is one of aromatic plants that contains insecticidal compounds that has the ability to fight against mosquitoes. In spite of citronella oil is a common natural-based mosquito repellent product, researches prove that citronella oil can give negative effects especially towards human skin. Therefore, P. radula has been chosen in this research. Based on previous research, solvent extraction and hydrodistillation extraction techniques are commonly being implemented to extract the insecticidal compounds in medicinal and aromatic plants regardless the side effect of all those traditional methods. These traditional extraction methods require longer extraction time, higher operating temperature and need organic solvent to extract the constituents in the plants that might result in toxic residual at the end of the extraction process. These might lead to chemical alteration and loss of volatile compound within the plant as well as give a negative effect to human and environment. In order to fill in the gap of the traditional extraction techniques, supercritical fluid extraction (SFE) method is being used to extract the compounds in P. radula plant in which the solvent used is environmental friendly and saves times. The extraction was conducted within a range of temperature (40 °C, 45 °C, 50 °C, 55 °C, and 60 °C) and pressure (100 bar, 150 bar, 200 bar, 250 bar, 300 bar, 350 bar, and 400 bar) a constant solvent flowrate 24 ml/min for 80 minutes extraction. The components within the extracted oil was analysed by using Gas Chromatography (GC) and Gas Chromatography-Mass Spectrometry (GC-MS). Once the extracted oil has been obtained, the effect of operating temperature and pressure was determined and being used to evaluate the potential of mosquito repellency. Based on the result obtained, the highest extraction yield with percentage of 1.7474 % as well as the solubility were obtained at the highest operating conditions with temperature and pressure of 60 °C and 400 bar, respectively. Meanwhile, as being analysed by GC and GC-MS, there are eight compounds were found which are geraniol (12.5488 %), citronellol (7.0016 %), 10-epi-y-eudesmol (3.7782 %), dauca-5,8-diene (1.8524 %), menthone (1.2328 %), germacrene D (0.9174 %), geranyl tiglate (1.1658 %), and delta-cadinene (0.3440 %). Finally, the extracted P. radula oil was found to be effective in repelling mosquito as concentration of 5%.