CLUSTER ION PRIMARY BEAM SOURCE FOR LIQUID SIMS

分析极小的生物化合物样品需要 质谱分析的灵敏度不断提高。 尤其如此 高质量样品和MS/MS分析。的最大损失 FAB和LSIMS的灵敏度发生在 将液体基质中的样品分子转换为蒸汽状态下的样品离子。 例如，牛胰岛素到离子的转化效率是 估计在1/300，000和1/3，000，000之间。 转换较大的 样品分子相对于蒸汽、离子而非蒸汽中性物的百分比 需要在液体基质表面上沉积更大的能量。 使用 原子簇离子，而不是通常的铯或氙原子， 初级束提供了一种增加表面能量沉积的方法 从而提高样品离子转换效率。 集群的发展 提出了一种基于液态金属离子源的离子枪， 产生用于LSIMS的具有高强度的锡簇，最高可达Sn 7+。 该枪将能够改装到大多数现有的质谱仪 据估计， 灵敏度超过现有的FAB或LSIMS枪。

The analysis of extremely small samples of biological compounds requires ever increasing sensitivity of mass spectrometry. This is especially the case with high mass samples and MS/MS analysis. The greatest loss of sensitivity in FAB and LSIMS occurs during the sputtering conversion of sample molecules in the liquid matrix to sample ions in the vapor state. For example, the conversion efficiency of bovine insulin to ions is estimated to be between 1/300,000 and 1/3,000,000. To convert a greater percentage of sample molecules to vapor, ions rather, than vapor neutrals requires a greater energy deposition on the liquid matrix surface. The use of cluster ions instead- of the customary cesium or xenon atoms for the primary beam, provides a means of increasing the surface energy deposition and thereby sample ion conversion efficiency. The development of a cluster ion gun is proposed, based on a liquid metal ion source which is capable of producing clusters of tin with high intensity up to Sn7+ for LSIMS use. The gun will be capable of retrofitting to most existing mass spectrometers with an estimated improvement of one to two orders of magnitude in sensitivity over existing FAB or LSIMS guns.