The National Research Centre for the Working Environment, 2100, Copenhagen, Denmark.
J Am Soc Mass Spectrom. 2013 Jul;24(7):1090-6. doi: 10.1007/s13361-013-0648-3. Epub 2013 May 11.
Limonene and its ozone-initiated reaction products were investigated in situ by low temperature plasma (LTP) ionization quadrupole time-of-flight (QTOF) mass spectrometry. Helium was used as discharge gas and the protruding plasma generated ~850 ppb ozone in front of the glass tube by reaction with the ambient oxygen. Limonene applied to filter paper was placed in front of the LTP afterglow and the MS inlet. Instantly, a wide range of reaction products appeared, ranging from m/z 139 to ca. 1000 in the positive mode and m/z 115 to ca. 600 in the negative mode. Key monomeric oxidation products including levulinic acid, 4-acetyl-1-methylcyclohexene, limonene oxide, 3-isopropenyl-6-oxo-heptanal, and the secondary ozonide of limonene could be identified by collision-induced dissociation. Oligomeric products ranged from the nonoxidized dimer of limonene (C20H30) and up to the hexamer with 10 oxygen atoms (C60H90O10). The use of LTP for in situ ozonolysis and ionization represents a new and versatile approach for the assessment of ozone-initiated terpene chemistry.
采用低温等离子体（LTP）电离四极杆飞行时间（QTOF）质谱法原位研究了柠檬烯及其臭氧引发的反应产物。氦气用作放电气体，通过与环境氧气反应，在玻璃管前产生约 850 ppb 的臭氧。将柠檬烯施加到滤纸后，将其放置在 LTP 余晖和 MS 入口前。瞬间，正模式下从 m/z 139 到约 1000，负模式下从 m/z 115 到约 600 出现了广泛的反应产物。通过碰撞诱导解离，可以鉴定出关键的单体氧化产物，包括乙酰丙酸、4-乙酰-1-甲基环己烯、柠檬烯氧化物、3-异丙烯基-6-氧庚醛和柠檬烯的次级臭氧化物。齐聚物产物范围从未氧化的柠檬烯二聚体（C20H30）到含有 10 个氧原子的六聚体（C60H90O10）。LTP 用于原位臭氧化和电离代表了评估臭氧引发萜烯化学的一种新的多功能方法。
