Characterization of toxic substances present in smoking tobacco using different spectroscopic techniques

Laser-induced breakdown spectroscopy (LIBS), a laser-based atomic spectroscopic technique, has been used to investigate the presence of toxic/heavy elements/compounds in various smoking tobacco samples. Based on the analysis of the LIBS spectra, the presence of toxic elements like Cr, Sb, Sr, Ni, and Ba, including organic elements C, H, N, O and other common elements like Fe, Mg, Na, and K, has been confirmed in the tobacco samples. Electronic bands of diatomic molecules such as CN and C2 are also observed in the LIBS spectra of the samples, which may be due to the presence of nicotine, chlorophyll, anthocyanin, etc., organic compounds. Calibration-free LIBS (CF-LIBS), a mathematical method, is used to determine the concentration of constituents using the intensity of the spectral lines of the species in the tobacco samples. Atomic absorption spectroscopy (AAS) technique is also used to determine the concentration of elements. The result obtained by AAS validates the result obtained using the CF-LIBS method. The presence of the organic compounds/molecules in the tobacco samples has been investigated using photoacoustic spectroscopy (PAS). Based on the analysis of the PAS spectrum, various organic compounds/molecules like nicotine, chlorophyll, pheophytin, β-carotenoid, anthocyanin, pheophytin, chlorophyllide, and bacteriochlorophy II are identified in the tobacco samples. UV-Visible absorption spectroscopy of these samples is used to compare the results obtained by PAS. Principal component analysis, a multivariate method, is applied to LIBS data to classify the various smoking tobacco samples based on their constituents. Our results show that ten smoking tobacco samples of different brands are forming three different clusters based on the similarity of their constituents.