Flow injection Fourier transform infrared determination of nicotine in tobacco

Abstract

A fully automated procedure is proposed for the Fourier transform infrared (FTIR) determination of nicotine in tobacco. The method is based on the on-line extraction of nicotine with CHCl₃. Samples, weighed inside empty extraction cartridges, were humidified with NH₃ and the cartridges were installed in a flow manifold in which they were extracted with 2 ml CHCl₃ for 2 min, then 400 µl of the extract were introduced into a micro-flow cell using a carrier of CHCl₃ and the IR spectrum was registered continuously. The absorbance, in the wavenumber range 1334–1300 cm^–1, was measured, obtaining a peak as a function of time. The area of this peak was interpolated on a calibration line established from standard solutions of nicotine in chloroform treated in the same way as samples. The method provided a limit of detection of 0.1 mg ml^–1 nicotine, an RSD lower than 2% and a sampling frequency of the whole procedure of 6 h^–1. Results obtained for natural samples of cut tobacco and cigar compared well with those obtained by a batch FTIR procedure, involving an off-line extraction with a total time of 16 min. However, for yellow tobacco cigarette, an on-line extraction time of 10 min was required to obtain a good recovery of nicotine.