Wu Qinghao, Zare Richard N
Chemistry, Stanford University, Stanford, CA, 94305, USA.
J Mass Spectrom. 2015 Jan;50(1):160-4. doi: 10.1002/jms.3509.
A two-step laser desorption lamp ionization source coupled to an ion trap mass spectrometer (LDLI-ITMS) has been constructed and characterized. The pulsed infrared (IR) output of an Nd:YAG laser (1064 nm) is directed to a target inside a chamber evacuated to ~15 Pa causing desorption of molecules from the target's surface. The desorbed molecules are ionized by a vacuum ultraviolet (VUV) lamp (filled with xenon, major wavelength at 148 nm). The resulting ions are stored and detected in a three-dimensional quadrupole ion trap modified from a Finnigan Mat LCQ mass spectrometer operated at a pressure of ≥ 0.004 Pa. The limit of detection for desorbed coronene molecules is 1.5 pmol, which is about two orders of magnitude more sensitive than laser desorption laser ionization mass spectrometry using a fluorine excimer laser (157 nm) as the ionization source. The mass spectrum of four standard aromatic compounds (pyrene, coronene, rubrene and 1,4,8,11,15,18,22,25-octabutoxy-29H,31H-phthalocyanine (OPC)) shows that parent ions dominate. By increasing the infrared laser power, this instrument is capable of detecting inorganic compounds.
一种与离子阱质谱仪联用的两步激光解吸灯电离源（LDLI-ITMS）已被构建并表征。Nd:YAG激光（1064 nm）的脉冲红外（IR）输出被导向一个抽真空至约15 Pa的腔室内的靶材，导致分子从靶材表面解吸。解吸的分子被真空紫外（VUV）灯（填充氙气，主要波长为148 nm）电离。产生的离子被存储并在一个从Finnigan Mat LCQ质谱仪改装而来的三维四极离子阱中进行检测，该离子阱在≥0.004 Pa的压力下运行。解吸的蔻分子的检测限为1.5 pmol，这比使用氟准分子激光（157 nm）作为电离源的激光解吸激光电离质谱法灵敏约两个数量级。四种标准芳香族化合物（芘、蔻、红荧烯和1,4,8,11,15,18,22,25-八丁氧基-29H,31H-酞菁（OPC））的质谱表明母离子占主导。通过增加红外激光功率，该仪器能够检测无机化合物。
