Fourier-transform infrared determination of nicotine in tobacco samples by transmittance measurements after leaching with CHCl3

A new procedure is proposed for the FT-IR spectrometric determination of nicotine in tobacco. The method is based on the extraction of nicotine in CHCl3 from tobacco samples, wetted with an aqueous solution of NH3 (0.1 M), and the measurement of absorbance in the stopped-flow mode at 1316 cm(-1), using a spectral baseline correction established from 1334 to 1300 cm(-1). The procedure developed does not requires a complex sample preparation, and provides a limit of detection of 0.045 mg ml(-1) nicotine, a sampling frequency of 3.3 h(-1) and a coefficient of variation of 0.3% for five independent measurements of a tobacco sample with a nicotine content of 1.5% w/w. The accuracy of this procedure was evaluated by recovery experiments on spiked natural samples, having obtained recovery percentages from 93 +/- 8 to 100 +/- 2 for amounts of 6-30 mg nicotine added. Additionally, an average value of 2.15 +/- 0.07% w/w was obtained for a powdered tobacco sample, analyzed by a reference procedure and by an external laboratory with a concentration of 2.02 +/- 0.05% w/w. The method was applied to the determination of nicotine, in different packed cigarettes of the Spanish market, having found a normal nicotine content from 1.1 to 1.9% w/w. (C) 1998 Elsevier Science B.V. All rights reserved.