Ultrasound-assisted extraction followed by dispersive liquid-liquid microextraction before gas chromatography-mass spectrometry for the simultaneous determination of flavouring compounds in tobacco additives

A new ultrasound-assisted extraction (UAE) followed by dispersive liquid-liquid microextraction (DLLME) method has been developed for the simultaneous determination of flavoring compounds, including safrole, coumarin, 6-methylcoumarin, 7-metheoxycoumarin, estragole, methyleugenol, pulegone and thujone, in tobacco additives. In this method, the targets were extracted from tobacco additive sample using ethanol by UAE. Then, 0.5 mL of the extract were used for the DLLME. In the DLLME, the target analytes in the extraction solvent were rapidly extracted into a small volume of chloroform and analyzed by chromatography-mass spectrometry (GC-MS). The parameters affecting the DLLME, including type and volume of extraction and disperser solvents, salt effect and extraction time, were investigated and optimized. Under the optimum conditions, the enrichment factors (EFs) ranged from 140 to 208. The linear relationship was obtained in the range of 0.4-928 ng mL(-1), which showed satisfactory linearity with correlation coefficients (r(2)) over 0.9989 for all the analytes. The limits of detection (LOD) were between 0.04 and 0.24 ng mL(-1) and the average recoveries were between 89.9 and 99.7% with relative standard deviations (RSDs) ranging from 2.5 to 6.7% in all cases. The method was successfully applied to the preconcentration and determination of these target compounds in tobacco additives.