Fourier-transform infrared determination of nicotine in tobacco samples by transmittance measurements after leaching with CHCl 3

Abstract

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 CHCl 3 from tobacco samples, wetted with an aqueous solution of NH 3 (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.