Jia Chunxiao

UPLC-MS n 法分析烟叶中蔗糖四酯类化合物

建立了烟叶样品中蔗糖四酯类化合物的超高效液相色谱-多级质谱（UPLC-MSn）分析方法。采用超声辅助萃取技术，用甲醇萃取烟叶样品中的蔗糖四酯，采用正交试验对超声萃取条件进行优化；萃取液经分离除杂后，在选择反应监测（SRM）模式下进行UPLC-MSn定性和定量分析，通过与标准品对照及对目标物的多级质谱数据进行分析，定性鉴定样品中的5组蔗糖四酯；并采用内标标准曲线法同时定量测定5组蔗糖四酯化合物的质量分数。结果表明：① 优化后的最佳萃取条件为料液比1：30[质量（g）：体积（mL）]，超声功率120 W，萃取时间40 min；② 定量分析方法的回收率在80.67%~89.35%之间，相对标准偏差均小于5%；相关系数r均大于或等于0.999 0；方法的检出限（LOD）和定量限（LOQ）分别为14.71~38.42、49.02~128.05 μg/kg。该方法前处理简单，定量分析灵敏度和准确度均较高，适合烟叶中蔗糖四酯类化合物的定量分析。

Determination of odor activity values (OAVs) of selected volatile organic acids in mainstream cigarette smoke

In this study, the effect of volatile organic acids on the expression of cigarette smoke sensory characteristics was investigated by evaluating the odor activity values (OAVs) of selected organic acids. The OAVs of the organic acids were calculated by the ratio of the organic acid contents in the mainstream cigarette smoke determined by GC-MS and their threshold values using the sensory evaluation method of functional thresholds for tobacco flavors. The results showed that the functional thresholds of 14 volatile organic acids were in the narrow range of 1.93×10 -9 and 4.61×10 -8 μg/cig. The total content of 14 volatile organic acids in mainstream smoke was 56.98 μg/cig, and acetic acid was the highest (33.54 μg/cig) and accounted for 58.86% of the total content. Isovaleric acid and valeric acid were 5.17 and 4.06 μg/cig (9.07% and 7.12% of the total content), respectively. According to the OAV, acetic acid (with an acid aroma note) could play a major role in the expression of cigarette aroma characteristics. Isovaleric acid, valeric acid and 4-methylvaleric acid (with a cheesy and fruity aroma note) and decanoic acid (with a fatty wax aroma note) were also important for expressing cigarette smokes aroma characteristics.

Analysis of Pyrolysate of 1-L-Phenylalanine-1-deoxy-D-fructose

The thermal mass loss and pyrolysis temperatures of 1-L-phenylalanine-1-deoxy-D-fructose(PDF) were tested by thermogravimetry-differential thermal analyzer(TG-DTA).The pyrolysis behavior of PDF was identified by on-line pyrolysis and gas chromatography/mass spectrometry(Py-GC/MS) at 350,450,550,650,750 and 850 ℃,respectively.The results showed that the primary pyrolysis temperature of PDF was 145.91 ℃,and the secondary one was 170.70 ℃.The thermal mass loss of PDF reached about 80% at 500 ℃.The major pyrolytic products of PDF were aromatic hydrocarbons and heterocyclic compounds.The number of pyrolytic products of PDF increased with the rise of temperature,especially aromatic hydrocarbons.