Influence of extraction methodologies on the analysis of five major volatile aromatic compounds of citronella grass (Cymbopogon nardus) and lemongrass (Cymbopogon citratus) grown in Thailand.

摘要

Extraction of major volatile aromatic compounds (VACs) from citronella grass and lemongrass by classical microhydrodistillation (MHD) and modern accelerated solvent extraction (ASE) was compared. 16 VACs were identified by GC/MS. GC-flame ionization detection was used for the quantification of 5 VACs (citronellal, citronellol, geraniol, citral and eugenol) to compare the extraction efficiency of the 2 methods. Linear range, LOD and LOQ were calculated for the 5 VACs. Intraday and interday precisions for the analysis of VACs were determined for each sample. Extraction recoveries, as calculated by a spiking experiment with known standards of VACs by ASE and MHD, were 64.9-91.2% and 74.3-95.2%, respectively. Extraction efficiency of the VACs was compared for 3 solvents with varying polarities (hexane, dichloromethane and methanol), 7 different temp. (ranging from 40 to 160 degrees C, with a gradual increment of 20 degrees C), 5 time periods (from 1 to 10 min), and 3 cycles (1, 2 and 3 repeated extractions). Optimum extraction yields of VACs were obtained when extractions were carried out for 7 min with dichloromethane and 2 extraction cycles at 120 degrees C. Results showed that the ASE technique is more efficient than MHD, because it results in improved yields and significant reductions in extraction time with automated extraction capabilities.