Institute of Structural Chemistry, Chemical Research Center, Hungarian Academy of Sciences, Pusztaszeri ut 59-67, 1025 Budapest, Hungary.
Anal Chem. 2010 Mar 15;82(6):2294-302. doi: 10.1021/ac902463q.
The collision energy or collision voltage necessary to obtain 50% fragmentation (characteristic collision energy/voltage, CCE or CCV) has been systematically determined for different types of molecules [poly(ethylene glycols) (PEG), poly(tetrahydrofuran) (PTHF), and peptides] over a wide mass (degrees of freedom) range. In the case of lithium-cationized PEGs a clear linear correlation (R(2) > 0.996) has been found between CCE and precursor ion mass on various instrument types up to 4.5 kDa. A similar linear correlation was observed between CCV and the mass-to-charge ratio. For singly and multiply charged polymers studied under a variety of experimental conditions and on several instruments, all data were plotted together and showed correlation coefficient R(2) = 0.991. A prerequisite to observe such a good linear correlation is that the energy and entropy of activation in a class of polymers is likely to remain constant. When compounds of different structure are compared, the CCV will depend not only on the molecular mass but the activation energy and entropy as well. This finding has both theoretical and practical importance. From a theoretical point of view it suggests fast energy randomization up to at least 4.5 kDa so that statistical rate theories are applicable in this range. These results also suggest an easy method for instrument tuning for high-throughput structural characterization through tandem MS: after a standard compound is measured, the optimum excitation voltage is in a simple proportion with the mass of any structurally similar analyte at constant experimental conditions.
已针对不同类型的分子[聚（乙二醇）（PEG）、聚（四氢呋喃）（PTHF）和肽]在很宽的质量（自由度）范围内系统地确定了获得 50%片段化所需的碰撞能或碰撞电压（特征碰撞能/电压，CCE 或 CCV）。在锂阳离子化 PEG 的情况下，在各种仪器类型上，在高达 4.5 kDa 的范围内，CCE 与前体离子质量之间存在明显的线性相关（R(2) > 0.996）。在 CCV 与质荷比之间也观察到类似的线性相关。对于在各种实验条件下和在几台仪器上研究的单电荷和多电荷聚合物，所有数据都一起绘制，并显示相关系数 R(2) = 0.991。观察到这种良好线性相关性的前提是一类聚合物中的激活能和熵可能保持恒定。当比较具有不同结构的化合物时，CCV 将不仅取决于分子量，还取决于激活能和熵。这一发现具有理论和实际意义。从理论角度来看，这表明在至少 4.5 kDa 的范围内能量快速随机化，从而使统计速率理论在该范围内适用。这些结果还为通过串联 MS 进行高通量结构特征描述的仪器调谐提供了一种简单的方法：在测量标准化合物后，在恒定实验条件下，任何结构相似的分析物的最佳激发电压与质量呈简单比例。
