Supercritical Fluid Extraction and Characterisation of Essential Oil from Moringa Oleifera Leaves

This work was aimed to extract and characterise the essential oils presented in the leaves of Moringa Oleifera using supercritical fluid extraction (SFE) and compare the results against those using the conventional Soxhlet extraction method. The oils extracted were analysed using GC-MS. The compounds were identified according to their retention indices and mass spectra (EI, 70eV). The effects of pressure (30MPa, 40MPa, 50MPa), temperature (40°C, 60°C, 80°C) and extraction time (60min, 90min and 120min) on the oil yield were investigated using a three-level orthogonal array design. The experimental results showed that while the oil yield increased with any of the three parameters, temperature had the most significant effect. The highest yield of 6.34% was obtained under the condition of pressure 50Mpa, temperature 60°C and an extraction time of 120min. The Soxhlet extraction was performed at 78°C for 8 hours using hexane as the solvent. A total of 43 components were identified in the Soxhlet extracted oil while only 12 components were detected in the SFE oil. Some lighter components that were in the Soxhlet extract were not detected in the SFE samples. This was because the volatile components in the SFE extracted oil escaped along with CO2 while for Soxhlet extraction; all the components were trapped in the solvent. However, the composition of the oil extracted by SFE under examined conditions is mostly similar and the major components were 1, 2-Benzenedicarboxylic acid, mono (2-ethylhexyl) ester, nonacosane, heptacosane, β-Amyrin etc.