Department of Chemistry, Kyungpook National University, Daegu, 702-701, Republic of Korea.
J Am Soc Mass Spectrom. 2013 Oct;24(10):1489-92. doi: 10.1007/s13361-013-0713-y. Epub 2013 Aug 18.
A proton source employing a nanostructured gold surface for use in (+)-mode laser desorption ionization mass spectrometry (LDI-MS) was evaluated. Analysis of perdeuterated polyaromatic hydrocarbon compound dissolved in regular toluene, perdeuterated toluene, and deuterated methanol all showed that protonated ions were generated irregardless of solvent system. Therefore, it was concluded that residual water on the surface of the LDI plate was the major source of protons. The fact that residual water remaining after vacuum drying was the source of protons suggests that protons may be the limiting reagent in the LDI process and that overall ionization efficiency can be improved by incorporating an additional proton source. When extra proton sources, such as thiolate compounds and/or citric acid, were added to a nanostructured gold surface, the protonated signal abundance increased. These data show that protons are one of the limiting components in (+)-mode LDI MS analyses employing nanostructured gold surfaces. Therefore, it has been suggested that additional efforts are required to identify compounds that can act as proton donors without generating peaks that interfere with mass spectral interpretation.
采用纳米结构化金表面的质子源在正模式激光解吸电离质谱（LDI-MS）中的应用进行了评估。分析溶解在常规甲苯、氘代甲苯和氘代甲醇中的全氘代多环芳烃化合物表明，无论溶剂体系如何，都生成了质子化离子。因此，可以得出结论，LDI 板表面的残留水是质子的主要来源。真空干燥后残留的水是质子的来源这一事实表明，质子可能是 LDI 过程中的限制试剂，通过引入额外的质子源可以提高整体的离子化效率。当向纳米结构化金表面添加额外的质子源，如硫醇化合物和/或柠檬酸时，质子化信号丰度增加。这些数据表明，质子是采用纳米结构化金表面的正模式 LDI-MS 分析中的限制因素之一。因此，有人建议需要进一步努力确定可以作为质子供体而不产生干扰质谱解释的峰的化合物。
