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Tobacco smoke is a complex mixture consisting of hundreds of toxic and carcinogenic chemicals, which may cause many diseases once inhaled. Among these toxic substances, radioactive and non-radioactive heavy metals present great health concerns to both active and passive smokers. However, conventional methodologies for characterizing heavy metals in smoke require intensive and time-consuming preparation procedures, and thus prevent their on-line applications. We report here a portable laser-induced breakdown spectroscopy (PLIBS) device for on-line detection of radioactive and non-radioactive heavy metals in tobacco smoke with ultra-high sensitivity. Two local cigarette brands were investigated, and a number of heavy metals were detected. In particular, several radioactive metals show very strong atomic emissions, and a limit of detection down to parts per trillion was obtained by single-shot PLIBS. The linear dependencies of their spectral intensities on the smoke concentrations were revealed, suggesting that the PLIBS is a promising tool for high-throughput and quantitative analysis of heavy metals in tobacco smoke. Tobacco emission dynamics were also investigated, and the results suggest the potential applications of the PLIBS in smoke risk assessment. [ABSTRACT FROM AUTHOR]

Multi-elemental analysis of particulate matters is highly desirable for the identification of their emission sources. However, the traditional techniques for single particle analysis usually require time-consuming sample preparation procedures. We report here a system that combines bright-field microscopy with laser induced breakdown spectroscopy (LIBS), allowing rapid and multi-elemental analysis of single particles. The improved throughput of the system was benefited from the use of ultra-thin polyethylene films for particle immobilization such that their spectra were collected successively. The simple composition of the films avoided their interferences in the particles' LIBS spectra. Moreover, the small thickness of the films allowed their rapid vaporization during laser ablation such that the plasma emissions from the particles were not quenched by their substrates. The performances of the system were demonstrated by studying the heterogeneity in particles' compositions and discriminating dust particles with very similar chemicals, suggesting that it is a promising tool for environmental risk assessment. Image 1 • Use of films for particle immobilization mitigated shockwave effects. • Simple composition of polyethylene film avoided substrate interferences. • Small thickness of the film prevented the quenching of LIBS signals by the film. • Multivariate analysis was used to discriminate particles with very close constituents. • Particle mixtures with various ratios can be well predicted by their spectra. [ABSTRACT FROM AUTHOR]

Self-absorption effect seriously affects the accuracy of the quantitative analysis in laser-induced breakdown spectroscopy (LIBS), confining the further development of the technology. In this study, three laser wavelengths at ultraviolet (355 nm), visible light (532 nm), and infrared (1064 nm) were selected to study the influence of laser wavelength on self-absorption effect in LIBS. The effect of the laser wavelength on the spectral stability was also investigated. The results showed that when the wavelength was 1064 nm compared with the wavelength of 355 nm and 532 nm, the full widths at half maximum (FWHMs) of aluminum (Al) I 396.2 nm were reduced by 39 % and 23 %, the FWHM of potassium (K) I 766.5 nm were reduced by 58 % and 22 %. In addition, the laser wavelength was also closely related to the stability of the spectral intensity. In comparison with the laser wavelengths of 532 nm and 1064 nm, the best spectral repeatability occurred when the laser wavelength was 355 nm. The relative standard deviation (RSD) of the K I 766.5 nm was only 2.5 %. The results indicate that laser wavelength affects the self-absorption effect and spectral stability of LIBS, which means selecting an appropriate laser wavelength can reduce self-absorption and improve stability. [ABSTRACT FROM AUTHOR]