shows the complete 1H NMR spectrum of the tobacco liqueur.
The figure depicts the intense signals of the sugars in the
mid-field region, less intense signals of higher alcohols and comparatively
small signals of aromatic compounds in the high-field
region. As the principal goal was to control for the health-relevant
compound nicotine, also measured was a nicotine standard solution
of 100 mg/l under the same experimental conditions. In the
spectrum of the standard solution, nicotine had resonances at d
8.60 ppm (td), d 8.00 ppm (q), d 7.57 ppm (m), d 3.36 ppm (s), d
2.93 ppm (m), d 2.48 ppm (s) and d 2.15 ppm (d). However, none
of them were found in the 1H NMR spectrum of the tobacco liqueur.
Since the reason for this could potentially have been a matrix
or solvent suppression effect, the 1H NMR spectra of the
tobacco liqueur was measured with several standard additions of
nicotine. All nicotine resonances were visible in this case. Furthermore,
to calculate the LOD/LOQ values of nicotine for this particular
matrix, it was decided to use the multiplet at d 8.60 ppm for
integration, because this lead to the largest sensitivity and the signal
was not interfered by the matrix itself (as it was observed in
the mid-field and high-field regions)