C5 - - 基三醇难题:异烯衍生的C5 - - H10 - - O3反应性吸收产品的结构特征和量化
Molly Frauenheim1, John Offenberg2, Zhenfa Zhang1
1Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States 27599.
概括
鉴定和量化了C5-基三醇,这些三醇对于估计异烯衍生的环氧 (IEPOX) 对PM2.5的贡献很重要. 有些不是人工制造品,而是IEPOX异构的结果,影响空气质量和气候.
科学领域:
- 大气化学 大气化学
- 有机地化学 有机地化学
- 分析化学 分析化学
背景情况:
- C5-基三醇 (2-甲基四醇) 是估计异烯衍生的环氧 (IEPOX) 对细颗粒物 (PM2.5) 的贡献的关键标记物.
- 二十年来,C5-基三醇的精确分子结构,PM2.5质量贡献和起源一直不确定,有可能成为分析工艺品.
- 了解这些化合物对于准确评估异烯氧化产品对空气质量和气候的影响至关重要.
研究的目的:
- 合成和表征潜在的C5-基三醇候选物,特别是3-甲基四二,4-二醇和3-甲基-1,2,4-三醇.
- 为了研究这些合成化合物的行为,使用气体染色学/电子冲击质谱学 (GC/EI-MS) 和水友相互作用液体染色学与电喷射电离相结合,与高分辨率四极点飞行时间质谱学 (HILIC/ESI-HR-QTOFMS) 接口.
- 确定C5-基三醇的实际大气来源,区分分析工件和IEPOX异构化产品.
主要方法:
- 合成C5H10O3反应性吸收产品候选物:3-甲基四二,4-二醇和3-甲基-1,2,4-三.
- 使用气体染色学/电子冲击质谱学 (GC/EI-MS) 与三甲基化进行分析.
- 使用非破坏性水友互动液体色谱学结合电喷离子化与高分辨率四极飞行时间质谱学 (HILIC/ESI-HR-QTOFMS) 接口的分析.
主要成果:
- 在实验室生成的IEPOX二级有机气溶 (SOA) 和大气SOA中确认了合成的C5-基三醇的存在.
- 使用GC/EI-MS在大气SOA中的量化3-甲基-1,2,4-和3-甲基四二-2,4-二醇.
- 估计~10%的测量3-甲基-1,2,4-三醇和~50%的3-甲基四二-2,4-二醇不是分析工件,而是源于粒子阶段的酸驱动IEPOX异构化.
- 在冲击物中检测到大量物质,表明C5-基三醇是半挥发性的.
- 据初步估计,这些化合物的总贡献为每年8.7万亿卡路里.
结论:
- 解决了C5-基三醇分子结构和起源的不确定性,证实它们部分来自IEPOX异构化.
- 证明了C5-基三醇的半挥发性,影响了它们在大气中的分布.
- 强调需要对这些化合物的气体与粒子分离,产量和大气氧化化学的未来研究,以充分了解它们对空气质量和气候的影响.
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