Lignin only accounts for about 6% of total mass in tobacco stem, but it influences the harmful substances in the side stream smoke of cigarette in a significant way. Traditional researches focus only on the determination of lignin content. In the present work, we investigate four typical imidazolium-based ionic liquids for efficient extraction of lignin under mild conditions and 1-ethyl-3-methylimidazolium diethylphosphate ([Emim][DEP]) shows the best results. The pretreatment of stem using water at 80 • C for 30 min can not only remove most of the sugars but also loose the microfibers. The extractive rate of lignin reaches 85.38% at 150 • C for 4 h and the purity of lignin is 90.21%.

RationaleThe aim of this work is to use a new design of online sampling photoionization mass spectrometer to analyze chemical ingredients in inhaled and exhaled cigarette smoke directly without separation.MethodsBased on vacuum ultraviolet photoionization time‐of‐flight mass spectrometry (VUV‐PI‐TOFMS) and a sampling system, a newly developed rapid online sampling design approach was used for the upper respiratory tract retention study of gaseous mainstream cigarette smoke components during smoking. The cigarette smoke inhaled or exhaled by seven subjects who displayed three different smoking patterns was directly sampled into a vacuum chamber, photoionized, and analyzed using TOFMS.ResultsFourteen species, comprising aldehydes, ketones, phenol, methanethiol, nitrogen‐containing heterocyclic compounds and unsaturated hydrocarbons, were identified in the cigarette smoke obtained from Virginia‐type cigarettes. The upper respiratory tract results for these compounds were similar for smokers with the three different smoking patterns: aldehyde and ketone constituents had a high retention level of more than 60%; phenol, methanethiol, and nitrogen‐containing heterocyclic compounds were retained at between 30% and 70%; and the retention of unsaturated hydrocarbons was about 20%–60%. The retention trend of the same smoke components in Virginia‐type cigarettes by subjects from the three smoking patterns (A, B, and C) was consistent, and the retentions all increased with increased smoking age (A < B < C).ConclusionsThis is the first report of a new online sampling design approach to the study of cigarette smoke components in inhaled and exhaled breath, to evaluate components retained in the upper respiratory tract by subjects with different smoking patterns. This method has good repeatability, and the results indicated that this is a very promising tool for the study of the retention of cigarette smoke constituents.

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