Comparison of methods for extraction of tobacco alkaloids

Ultrasound and microwave techniques were used to extract tobacco alkaloids, and response surface methodology was used to optimize extraction conditions. Ultrasonic technique factors were temperature, 30-85 degrees C; time, 3-45 min; solvent volume, 8-80 mL. Microwave extraction factors were pressure, 15-75 psi; time, 3-40 min; power, 30-90% of the maximum magnetron power of 650 W. Soxhlet and solvent AOAC-modified extraction methods were also applied after some improvements. Nicotine, nornicotine, anabasine, and anatabine were quantified by gas chromatography. A steam distillation International Standards Organization method for total alkaloid evaluation was used as reference. The results obtained by the different methods were compared using a least squares deviation test. The ultrasonic and the proposed modified-AOAC extraction method were the more convenient with regard to practicability and precision. The relative deviations (n = 5) were as follows: For the ultrasonic method in low-level alkaloid tobaccos, 0.7% nicotine and 1.4-14% minor alkaloids; in high-level alkaloid tobaccos, 2.4% nicotine and 4.5-5.1% minor alkaloids. For the modified AOAC method in low-level alkaloid tobaccos, 0.9% nicotine and 2.4-11.6% minor alkaloids; and in high-level alkaloid tobaccos, 1.7% nicotine and 2.0-2.4% minor alkaloids.