Ultrasound-assisted extraction and dispersive liquid–liquid microextraction coupled with gas chromatography-mass spectrometry for the sensitive determination of essential oil components in lavender

In this research, a novel method based on ultrasound-assisted extraction and dispersive liquid–liquid microextraction (UAE-DLLME) coupled with gas chromatography-mass spectrometry (GC-MS) has been successfully developed for the determination of essential oil constituents in lavender. The effective parameters of UAE-DLLME, including the type of extraction solvent, type and volume of preconcentration solvent, type and volume of disperser solvent, extraction temperature, and extraction time, were studied and optimized in detail. The optimal analytical conditions were as follows: 2 mL 50% ethanol as the extraction solvent, 150 μL methanol as the disperser solvent, 40 μL CCl4 as the preconcentration solvent, an extraction time of 20 min and an extraction temperature of 50 °C. Under the optimum conditions, a total of 13 samples of three varieties of lavender were analyzed and 64 compounds were identified. The precision of UAE-DLLME-GC-MS was evaluated and the relative standard deviation (RSD) was below 9% (n = 5). Good linearity with correlation coefficients of >0.9982 was obtained; limits of detection ranging from 1.75 to 7.50 ng indicated high sensitivity. Principal component analysis (PCA) was used to distinguish different varieties of lavender. This is the first application of UAE-DLLME for the analysis of essential oil constituents in lavender. The results showed that UAE-DLLME-GC-MS is a fast, sensitive, simple and small sample consumption method for the determination of essential oils in plant materials.