Analysis of cigarette smoke by laser desorption mass spectrometry

Tee-Shaped Sample Introduction Device Coupled with Direct Analysis in Real-Time Mass Spectrometry for Gaseous Analytes

Ambient ionization mass spectrometry (AIMS) is simple to operate for analytes adsorbed on the surface of various shaped probes. However, gaseous substances or liquids that are easy to evaporate, diffuse, and escape in the atmosphere are harder to capture. In this work, a Tee-shaped sample introduction device coupled with direct analysis in real time mass spectrometry (DART-MS) is developed. The Tee-shaped device is placed between the DART ion source and the MS inlet with a heated sample transfer tube. Gaseous samples from either a Tedlar sampling bag or liquids evaporated from a graduated syringe were tested. The Tee-shaped device was used for several volatile organic compounds with a wide range of boiling points, and detection limits of ng/mL to fg/mL were obtained. To test the device for real-life samples, puff-by-puff analysis of a complex gaseous mainstream smoke was performed. Individual puffs can be analyzed rapidly, and there is no cross contamination between consecutive puffs. The dynamic changes of chemical components among different puffs for different types of cigarettes can be observed. This work provides a universal Tee-shaped sampling device to enhance AIMS for the analysis of volatile compounds and gases, which is adapted to different sampling modules applicable for various forms of samples. The device enables direct exploration of chemical components in complex gaseous samples without tedious sample preparation and time-consuming LC or GC separation.

Study of the mainstream cigarette smoke aerosols by Fourier transform ion cyclotron resonance mass spectrometry coupled to laser/desorption and electrospray ionization - Additional insights on the heteroaromatic components

RATIONALE

The chemical composition of the particulate phase of cigarette smoke inhaled by the active smoker is still poorly known in spite of its importance from a health point of view. A non-targeted approach is applied to cigarette smoke particles collected on a quartz filter to obtain an as complete as possible description of this complex mixture.

METHODS

A home-made smoking machine including devices for volatile organic compounds (VOCs) and particle sampling was used. The validation of the cigarette smoking and cigarette smoke collection procedures was conducted by the quantification of some compounds by gas chromatography/mass spectrometry (GC/MS). The particles were investigated by Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) directly after their collection on quartz filters by laser/desorption ionization (LDI) or after extraction with CH2 Cl2 by electrospray ionization (ESI).

RESULTS

The determination of the benzene, toluene, ethylbenzene and xylenes (from 2 to 35 μg/cigarette) and nicotine (0.68 ± 0.05 mg/cigarette) validated the used sampling method. The complementarity of the LDI and ESI sources for the cigarette smoke analysis was established. The ESI analyses evidenced polar compounds and components with a pyridine group and LDI ensured the detection of poly-condensed heteroaromatic species. Finally, this methodology was employed to characterize particles from cigarettes with or without flavoring additives.

CONCLUSIONS

Some insights into the composition of cigarette smoke inhaled by active smokers have been obtained. The ~1750 observed features revealed the huge complexity of cigarette smoke particles and the diversity of the possible associated health issues. Both heteroaromatic and highly oxygenated compounds produced by combustion and pyrolysis have been highlighted.

Ambient desorption/ionization mass spectrometry using a liquid sampling-atmospheric glow discharge (LS-APGD) ionization source

A novel approach to ambient desorption/ionization mass spectrometry (ADI-MS) is described, based on a recently developed liquid sampling-atmospheric pressure glow discharge (LS-APGD) ionization source. The device is essentially unmodified relative to its implementation in elemental mass spectrometry, where the operational space is characterized by low operation power (<10 W) and low solution delivery rates (<50 μL min(-1)). In this implementation, the plasma is produced between a Ni anode and an electrolytic liquid (1 M HNO3) cathode flowing through a glass capillary that is angled towards the sample surface, at a distance of ~2 mm away. Analyte species can be desorbed/ionized from neat solution residues and complex solid samples. The ADI-LS-APGD source is mounted onto the source interface of a Thermo Finnigan LCQ Advantage Max quadrupole ion trap mass spectrometer without modifications to the instrument faceplate or ion optics. Described here is the initial evaluation of the roles of source geometry and working parameters, including electrolytic solution composition and plasma current, on the response of caffeine residues, with preliminary limits of detection based on the relative standard deviation of the spectral background suggested to be on the 10-pg level. Demonstrative spectra are presented for green tea extracts and raw leaves, coffee beans, a dried (raw) tobacco leaf, an analgesic tablet, and paper currency. Versatility is further revealed through the determination of components in common cigarette smoke. In each case, the spectra are characterized by (M + H)(+) species of the expected constituents. The capacity for a single source to perform both in solution and particulate elemental analysis (as shown previously) and ADI of molecular species is unique in the realm of mass spectrometry.

Microprobe sampling--photo ionization-time-of-flight mass spectrometry for in situ chemical analysis of pyrolysis and combustion gases: examination of the thermo-chemical processes within a burning cigarette

A microprobe sampling device (μ-probe) has been developed for in situ on-line photo ionization mass spectrometric analysis of volatile chemical species formed within objects consisting of organic matter during thermal processing. With this approach the chemical signature occurring during heating, pyrolysis, combustion, roasting and charring of organic material within burning objects such as burning fuel particles (e.g., biomass or coal pieces), lit cigarettes or thermally processed food products (e.g., roasting of coffee beans) can be investigated. Due to its dynamic changes between combustion and pyrolysis phases the cigarette smoking process is particularly interesting and has been chosen as first application. For this investigation the tip of the μ-probe is inserted directly into the tobacco rod and volatile organic compounds from inside the burning cigarette are extracted and real-time analyzed as the glowing front (or coal) approaches and passes the μ-probe sampling position. The combination of micro-sampling with photo ionization time-of-flight mass spectrometry (PI-TOFMS) allows on-line intrapuff-resolved analysis of species formation inside a burning cigarette. Monitoring volatile smoke compounds during cigarette puffing and smoldering cycles in this way provides unparalleled insights into formation mechanisms and their time-dependent change. Using this technique the changes from pyrolysis conditions to combustion conditions inside the coal of a cigarette could be observed directly. A comparative analysis of species formation within a burning Kentucky 2R4F reference cigarette with μ-probe analysis reveals different patterns and behaviors for nicotine, and a range of semi-volatile aromatic and aliphatic species.

Laser-induced Fourier transform ion cyclotron resonance mass spectrometry of organic and inorganic compounds: methodologies and applications

The combination of a laser with a Fourier transform ion cyclotron resonance mass spectrometer (FTICRMS) enables a variety of MS experiments to be conducted. The laser can be used either as an intense photonic source for the photoionization of neutral species introduced in a variety of ways into the FTICR cell, or it can be made to directly interact with a solid, generating gas-phase ions. Depending on the experimental conditions used, various laser-matter interactions can occur. When high laser energy (also referred to as power density or irradiance) is used, laser ablation (LA) processes lead to the release of species into the gas phase, a significant fraction of which are ionic. The number of ions decreases with the irradiance. For low irradiance values, the so-called laser desorption (LD) regime applies, where the expelled species are mainly neutrals. LA-FTICRMS and LD-FTICRMS can be used to study a wide range of materials, including mineral, organic, hybrid and biological compounds (although matrix-assisted laser desorption ionization, MALDI, which is not reviewed in this paper, is more commonly applied to biological compounds). This paper will review a selection of methodological developments and applications in the field of laser ionization FTICRMS, LD-FTICRMS, and LA-FTICRMS for the analysis of organics and inorganics in complex mixtures, emphasizing insoluble materials. Specifically, silicate- and carbon-based complex materials as well as organic compounds will be examined due to their relevance to natural environmental and anthropogenic matrices.

Determination of nicotine in mainstream smoke on the single puff level by liquid-phase microextraction coupled to matrix-assisted laser desorption/ionization Fourier transform mass spectrometry

A method coupling liquid-phase microextraction with matrix-assisted laser desorption/ionization Fourier transform mass spectrometry (LPME/MALDI-FTMS) was developed to measure the content of nicotine in mainstream smoke at the single puff level. Glycerol was utilized as a matrix additive in the sample preparation to improve the homogeneity of analyte distribution in a sample spot. Good repeatability of the MALDI-MS signal (RSD <9%) was achieved by the method. Selective LPME facilitated the separation and purification of basic components from cigarette smoke. The LPME device was coupled to a smoking machine, and each puff of one cigarette could be gathered by this modified machine. The amount of nicotine in the mainstream smoke was measured at the single puff level by LPME/MALDI-FTMS. The method was simple and selective and was sufficiently sensitive to detect nicotine in each puff of one cigarette. The method thus offered an alternative approach to the study of the formation mechanism of cigarette smoke constituents.