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OPEN ACCESS PLUS
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Contents
8(4): Pp. 412 - 426
Jan B. Wooten
[Open Access Plus] |
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Cigarette smoke free radicals have been the subject of many years of investigation. Recently, individual acyl and carbamoyl radicals in fresh whole cigarette smoke were isolated, identified, and quantified by HPLC-mass spectrometry for the first time. These carbon-centered radicals do not conform to the established “steady-state model” for radical formation in gas-phase cigarette smoke. In separate studies, NO2 in fresh whole mainstream smoke has been measured on a puff-to-puff basis by highly precise and rapid tunable infrared diode laser spectroscopy (TILDAS). Only the first puff contained a significant amount of NO2 and its overall yield was substantially lower than previously reported. Nevertheless, when the smoke was passed through a Cambridge filter pad, NO2 appeared in the filtered gas-phase smoke during every puff, suggesting that NO2 forms directly on the pad. For fresh smoke, these results also challenge the applicability of the steady-state mechanism, which postulates that NO2 in the smoke itself is an essential intermediate for gas-phase radical formation. In this review, the historical investigations of cigarette smoke radicals are re-examined and the implications of the new spectroscopic and radical trapping data are discussed. Possible alternative mechanisms for radical formation in cigarette smoke are proposed. When combined with data from previous corroborating reports, these recent results raise serious issues about the use of the Cambridge pad, which is conventionally used to separate gas smoke constituents from whole smoke, but may introduce more artifacts of measurement for certain reactive smoke constituents than previously appreciated.
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8(4): Pp. 349 - 359
C. Liu, K. G. McAdam and T. A. Perfetti
[Open Access Plus] |
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This short review summarises some fundamental aspects of cigarette combustion and smoke formation, including how cigarettes burn, how cigarette smoke is formed and the complex and reactive nature of its composition. Particular emphasis has been placed on important factors which have to be controlled when generating, trapping and analyzing cigarette smoke. Examples are provided which demonstrate the sensitivity of cigarette smoke composition to the way it is produced and measured, a subject of particular importance for redox sensitive species such as free radicals and multiple valency-state metals. Recent regulatory interest in smoke constituent yields is summarized, as well as risk assessment approaches which have sought to identify the smoke constituents which make the greatest contribution to smoking related diseases. Limitations of these approaches are discussed, and a number of other aspects of cigarette smoke that have been suggested to contribute to the incidence of smoking related diseases are highlighted.
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4(4): Pp. 317 - 329
Ralf Schirrmacher, Carmen Wangler and Esther Schirrmacher
[Open Access Plus] |
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In this short review we describe recent methods and novel trends for the introduction of fluorine-18 into molecules which in turn are intended to serve as imaging agents for the in vivo imaging modality positron emission tomography (PET). These 18F-labeling schemes are based on enzymatic fluorination, the use of ionic liquids, protic solvents acting as catalysts, application of “click chemistry”, thiol-reactive labeling agents for peptide and protein labeling and the most recent introduction of “non-classical” radiochemistry based on organo-phosphorous, organo-boron and organo-silicon radiochemistry. The latter approach for the first time introduced an 18F-chemistry characterized by high selectivity and unique efficiency making complicated work-up procedures obsolete.
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