Vortex-assisted extraction in tandem with dispersive liquid–liquid microextraction followed by GC-MS for determination of Achillea wilhelmsii essential oil
A simple, fast and efficient combined extraction/preconcentration method composed of vortex-assisted extraction (VAE) and dispersive liquid–liquid microextraction (DLLME) coupled with gas chromatography-mass spectrometry (GC-MS) was developed for determination of essential oil constituents of the plant Achillea wilhelmsii. Methanol and chloroform were used as the extraction and preconcentration solvents, respectively. The effective parameters of the extraction process were optimized by the one-at-a-time method. The optimal conditions were determined as 25 μL of chloroform, 7.5% (w/v) of salt concentration, and 2 min of extraction time. The linear dynamic range (LDR) for the oil components was within 0.01–100 and 0.1–100 mg L−1 characterized by determination coefficients (R2) between 0.9990 and 0.9998. The limits of detection (LODs) were from 3.0 to 30.0 μg L−1. The relative standard deviations (RSDs, n = 5) were 2.3–4.7%. The enhancement factors (EFs) ranged from 80 to 91. The extraction yield of the essential oil by hydrodistillation was 1.02% (w/w). The main components of the Achillea wilhelmsii essential oil were determined as: borneol (21.23%), cis-chrysanthenyl acetate (20.92%), camphor (9.24%), trans-chrysanthenyl acetate (8.63%) and 1,8-cineole (7.16%). The antimicrobial activity of the essential oil against 10 different species of bacteria with two most commonly used methods of the disc diffusion method (DDM) and the broth dilution method (BDM) was investigated. The essential oil showed inhibitory activity against Escherichia coli, Bacillus cereus, and Staphylococcus aureus with the highest activity for Escherichia coli.