Mukarakate Calvin, Scheer Adam M, Robichaud David J, Jarvis Mark W, David Donald E, Ellison G Barney, Nimlos Mark R, Davis Mark F
National Bioenergy Center, National Renewable Energy Laboratory, Golden, Colorado 80401, USA.
Rev Sci Instrum. 2011 Mar;82(3):033104. doi: 10.1063/1.3563704.
We have designed and developed a laser ablation∕pulsed sample introduction∕mass spectrometry platform that integrates pyrolysis (py) and∕or laser ablation (LA) with resonance-enhanced multiphoton ionization (REMPI) reflectron time-of-flight mass spectrometry (TOFMS). Using this apparatus, we measured lignin volatilization products of untreated biomass materials. Biomass vapors are produced by either a custom-built hot stage pyrolysis reactor or laser ablation using the third harmonic of an Nd:YAG laser (355 nm). The resulting vapors are entrained in a free jet expansion of He, then skimmed and introduced into an ionization region. One color resonance-enhanced multiphoton ionization (1+1 REMPI) is used, resulting in highly selective detection of lignin subunits from complex vapors of biomass materials. The spectra obtained by py-REMPI-TOFMS and LA-REMPI-TOFMS display high selectivity and decreased fragmentation compared to spectra recorded by an electron impact ionization molecular beam mass spectrometer (EI-MBMS). The laser ablation method demonstrates the ability to selectively isolate and volatilize specific tissues within the same plant material and then detect lignin-based products from the vapors with enhanced sensitivity. The identification of select products observed in the LA-REMPI-TOFMS experiment is confirmed by comparing their REMPI wavelength scans with that of known standards.
我们设计并开发了一种激光烧蚀∕脉冲进样∕质谱平台，该平台将热解（py）和∕或激光烧蚀（LA）与共振增强多光子电离（REMPI）反射式飞行时间质谱（TOFMS）相结合。使用该仪器，我们测量了未处理生物质材料的木质素挥发产物。生物质蒸气通过定制的热台热解反应器或使用Nd:YAG激光的三倍频（355 nm）进行激光烧蚀产生。产生的蒸气被夹带在氦气的自由射流膨胀中，然后被截取并引入电离区域。采用单共振增强多光子电离（1+1 REMPI），从而能够从生物质材料的复杂蒸气中高度选择性地检测木质素亚基。与电子轰击电离分子束质谱仪（EI-MBMS）记录的光谱相比，热解-REMPI-TOFMS和激光烧蚀-REMPI-TOFMS获得的光谱显示出高选择性和减少的碎片化。激光烧蚀方法证明了能够在同一植物材料中选择性地分离和挥发特定组织，然后以更高的灵敏度从蒸气中检测基于木质素的产物。通过将LA-REMPI-TOFMS实验中观察到的选定产物的REMPI波长扫描与已知标准品的扫描进行比较，证实了这些产物的鉴定。
