Isolation and GC Analysis of Fatty Acids: Study Case of Stinging Nettle Leaves

Urtica dioica L. is perennial plant with remarkable medical properties and has been widely used in folk medicine and as a food. Fatty acids presented in its leaves were extracted applying three different techniques: classic, automated Soxhlet, and supercritical fluid extraction (SFE). SFE was performed at three different pressures (100, 200, and 300 bar) and two different temperatures (40 and 60°C). Obtained extract was analyzed using GC-FID analytical technique in order to obtain fatty acid profile samples. The highest yield was obtained in the case of automated Soxhlet extraction (218.907 mg/g), while the lowest was observed in the case of classic extraction (15.031 mg/g). Soxhlet approach pro- vided the highest yield of saturated fatty acids (173.348 mg/g), while supercritical fluid extraction gave better results in the case of unsaturated fatty acids (60.062 mg/g). Deeper analysis of SFE extracts revealed relationship between extraction parameters (tempera-ture and pressure) and yields of fatty acids where lower pressure ensured higher yield of unsaturated while higher pressure gave higher yield of saturated acids. On the other hand, increasing in temperature at isobaric conditions negatively influenced the yield of fatty acids except in the case of 300 bar where yield was higher at 60°C.