Puff-Resolved Analysis and Selected Quantification of Chemicals in the Gas Phase of E-Cigarettes, Heat-Not-Burn Devices, and Conventional Cigarettes Using Single-Photon Ionization Time-of-Flight Mass Spectrometry (SPI-TOFMS): A Comparative Study.

INTRODUCTION: A wide array of alternative nicotine delivery devices (ANDD) has been developed and they are often described as less harmful than combustible cigarettes. This work compares the chemical emissions of three ANDD in comparison to cigarette smoke. All the tested ANDD are characterized by not involving combustion of tobacco. AIMS AND METHODS: Single-photon ionization time-of-flight mass spectrometry (SPI-TOFMS) is coupled to a linear smoking machine, which allows a comprehensive, online analysis of the gaseous phase of the ANDD aerosol and the conventional cigarette (CC) smoke. The following devices were investigated in this study: a tobacco cigarette with a glowing piece of coal as a heating source, an electric device for heating tobacco, and a first-generation electronic cigarette. Data obtained from a standard 2R4F research cigarette are taken as a reference. RESULTS: The puff-by-puff profile of all products was recorded. The ANDD show a substantial reduction or complete absence of known harmful and potentially harmful substances compared with the CC. In addition, tar substances (i.e. semivolatile and low volatile aromatic and phenolic compounds) are formed to a much lower extent. Nicotine, however, is supplied in comparable amounts except for the investigated electronic cigarette. CONCLUSIONS: The data show that consumers switching from CC to ANDD are exposed to lower concentrations of harmful and potentially harmful substances. However, toxicological and epidemiological studies must deliver conclusive results if these reduced exposures are beneficial for users. IMPLICATIONS: The comparison of puff-resolved profiles of emissions from different tobacco products, traditional and alternative, may help users switch to lower emission products. Puff-resolved comparison overcomes technical changes, use modes between products and may help in their regulation.

Cyclo-pnicta-triazanes: biradicaloids or zwitterions?

Bulky triazenides were utilized in the reaction with pnictogen(III) chlorides (ECl3, E = P, As, Sb, and Bi) yielding triaza-pnicta-butene analogues of the type R-N═N-N(R)-ECl2 (R = Ter = 2,6-bis(2,4,6-trimethylphenyl)phenyl). Subsequent reduction of these dichloro-species afforded unprecedented four-membered group 15 heterocycles [E(µ-NTer)2N] bearing one dicoordinate pnictogen and nitrogen atom. These N3E rings represent species at the borderline between singlet biradicaloids and zwitterions with diminished reactivity compared to known singlet biradicaloids. The N3P compound could be identified, while N3As and N3Sb species as well as the precursor compounds were fully characterized.

Cm(III) retention by calcium silicate hydrate (C-S-H) gel and secondary alteration phases in carbonate solutions with high ionic strength: A site-selective TRLFS study.

We studied the Cm(III) retention by calcium silicate hydrate (C-S-H), portlandite (Ca(OH)2) and their alteration products calcite, vaterite, and aragonite in high ionic strength carbonate-containing solutions representing specific formation waters. For this, we synthesized C-S-H gels with calcium to silicon (C/S) ratios of 1.0 and 2.0 in the absence and presence of Cm(III), resulting in Cm(III)-free and Cm(III) doped C-S-H gel, respectively. For phase identification purposes we applied X-ray diffraction (XRD) while for the identification of the Cm(III)/C-S-H binding mode we applied site-selective time-resolved laser-induced luminescence spectroscopy (TRLFS). The stability of Cm(III) doped phases under repository-relevant conditions was evaluated by studying the time-dependent release of Cm(III) from the Cm(III) doped C-S-H gel into leaching solutions containing 0.02 M NaHCO3 or 2.5 M NaCl/0.02 M NaHCO3 over 60 d. Speciation changes of Cm(III) due to leaching were followed with TRLFS while C-S-H structure alterations and secondary phase formation were monitored with XRD. From the results it could be concluded that Cm(III) is not mobilized by aqueous carbonate but either remains incorporated in the C-S-H structure and portlandite or becomes partially re-immobilized into secondary CaCO3 phases. The presence of NaCl led to an accelerated conversion of metastable secondary CaCO3 phases into calcite.

Stability of U(VI) doped calcium silicate hydrate gel in repository-relevant brines studied by leaching experiments and spectroscopy.

The stability of calcium silicate hydrate (C-S-H) gel doped with uranium to form calcium uranium silicate hydrate (C-U-S-H) gel was investigated in 2.5 M NaCl, 2.5 M NaCl/0.02 M Na2SO4, 2.5 M NaCl/0.02 M NaHCO3 or 0.02 M NaHCO3 solutions relevant to the geological disposal of radioactive waste. The C-U-S-H gel samples were synthesized by direct U(VI) incorporation and characterized with time-resolved laser-induced luminescence spectroscopy (TRLFS), infrared (IR) spectroscopy, powder X-ray diffraction (XRD), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). Time-dependent pH changes as well as the Ca, Si and U release from C-U-S-H gels into the brines, determined by inductively coupled plasma mass spectrometry (ICP-MS), were monitored for three calcium-to-silicon (C/S) ratios (0.99, 1.55 and 2.02) over 32 d. Subsequently, changes of the U(VI) speciation and C-S-H mineralogy caused by leaching were investigated with TRLFS, IR spectroscopy and XRD. Results indicated that composition and pH value of the leaching solution, the presence of portlandite as well as formation and solubility of calcite as secondary phase determine the U(VI) retention by C-S-H gel under high saline and alkaline conditions. At high ionic strengths, the Ca release from C-S-H and secondary phases like calcite is increased. Under hyperalkaline conditions only small amounts of U(VI) were released during leaching. A decrease of the pH due to the additional presence of carbonate was linked with an increased U(VI) release from C-S-H gel leading to the formation of aqueous calcium uranyl carbonate in the supernatant solution.