GC-AED studies of nicotine fate in a burning cigarette

An atomic emission detector (AED) for a gas chromatograph (GC) can be used to selectively detect compounds labeled with stable isotopes, such as D, C-13, and N-15. This capability can be used to determine precursor-fate relationships within complex matrices, using stable isotopes rather than radiolabeled isotopes. Employing stable isotopes removes the safety consideration associated with radiolabeling studies. Two previous reports have employed GC-AED in fate studies for C-13-labeled precursors. The goal of this study was to evaluate the utility of GC-AED for precursor-fate determinations in tobacco science; In this work, GC-AED was used to determine the fate of nicotine-d(4) in a burning cigarette. GC-MSD was then: employed to identify the compounds that the AED indicated contained D. Spectral confirmation of the presence of D was performed on each chromatographic peak of interest with both AED and MSD to ensure that the identification of the products was correct Nicotine and nicotine-de standards were used to evaluate the effect of coelution of unlabeled compounds with the labeled compounds on the AED response for D. It was shown that the AED response for D at lambda = 308 nm decreases with increased concentration of unlabeled compound. Detection at lambda = 656 nm, however, is unaffected by the presence of the unlabeled compound. Compound-independent calibration is also possible at this wavelength. GC-AED studies with nicotine-d(4) core injected into cigarettes demonstrated that most of the nicotine (79%) is distilled; unchanged, into the mainstream (MS) and sidestream (SS) smoke. The degradation products that do occur include 3-substituted pyridines and nicotine-oxidation products. These are found only in the SS smoke.