Department of Chemistry, Louisiana State University, Baton Rouge, LA, USA.
J Am Soc Mass Spectrom. 2013 Jul;24(7):1108-15. doi: 10.1007/s13361-013-0631-z. Epub 2013 Apr 30.
Particles were ablated from laser desorption and inlet ionization matrix thin films with a UV laser in reflection and transmission geometries. Particle size distributions were measured with a combined scanning mobility particle sizer (SMPS) and aerodynamic particle sizer (APS) system that measured particles in the size range from 10 nm to 20 μm. The matrixes investigated were 2,5-dihydroxybenzoic acid (DHB), α-cyano-4-hydroxycinnamic acid (CHCA), sinapic acid (SA), 2,5-dihydroxy-acetophenone (DHAP), and 2-nitrophloroglucinol (NPG). Nanoparticles with average diameters between 20 and 120 nm were observed in both transmission and reflection geometry. The particle mass distribution was significantly different in reflection and transmission geometry. In reflection geometry, approximately equal mass was distributed between particles in the 20 to 450 nm range of diameters and particles in the 450 nm to 1.5 μm diameter range. In transmission mode, the particle mass distribution was dominated by large particles in the 2 to 20 μm diameter range. Ablation of inlet ionization matrices DHAP and NPG produced particles that were 3 to 4 times smaller compared with the other matrices. The results are consistent with ion formation by nanoparticle melting and breakup or melting and breakup of the large particles through contact with heated inlet surfaces. ᅟ
采用紫外激光在反射和透射两种几何条件下从激光解吸和离子导入基质薄膜中去除颗粒。采用组合式扫描迁移率颗粒粒径分析仪（SMPS）和空气动力学粒径分析仪（APS）系统测量粒径分布，测量范围为 10nm 至 20μm。研究的基质有 2,5-二羟基苯甲酸（DHB）、α-氰基-4-羟基肉桂酸（CHCA）、芥子酸（SA）、2,5-二羟基苯乙酮（DHAP）和 2-硝基-对苯二酚（NPG）。在透射和反射两种几何条件下均观察到平均直径在 20nm 至 120nm 之间的纳米颗粒。在反射和透射几何条件下，粒径在 20 至 450nm 范围内的颗粒和粒径在 450nm 至 1.5μm 范围内的颗粒的质量分布差异显著。在透射模式下，粒径在 2 至 20μm 范围内的大颗粒主导了颗粒的质量分布。与其他基质相比，离子导入基质 DHAP 和 NPG 的去除颗粒小 3 至 4 倍。结果与纳米颗粒熔化和破裂形成离子或大颗粒通过与加热的入口表面接触而熔化和破裂的情况一致。
