Ion detection limitations to mass resolution in matrix-assisted laser desorption time-of-flight mass spectrometry.
Ion detection limitations to mass resolution in matrix-assisted laser desorption time-of-flight mass spectrometry.
复制标题
基质辅助激光解吸飞行时间质谱中离子检测对质量分辨率的限制。
DOI：
10.1002/rcm.1290061112
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发表时间：
1992
期刊：
影响因子：
--
通讯作者：
Gilfrich,NL
中科院分区：
文献类型：
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作者：
Brown,RS;Gilfrich,NL
离散倍增极电子倍增器中的离子检测过程可能导致飞行时间质谱（TOF-MS）中更高质荷比（m/z）离子种类的质量分辨率损失。这种分辨率损失归因于离子检测器中的传播时间延迟和信号展宽。这被推测是由于在初级离子与离子检测器的第一离子表面碰撞时初始产生的次级离子种类的分布的产生。比较由标准离散倍增电极离子检测器（其放大由初级离子的冲击产生的负电荷种类）和经修改以仅响应由初级离子冲击产生的正电荷次级离子种类的检测器产生的信号。对于具有标准检测器几何结构的较高m/z离子的离子信号被认为是由于窄信号分量和宽信号分量，窄信号分量最可能是由于二次电子和/或非常低质量的二次离子（H-）的生成，宽信号分量显然是由于二次离子花费显著量的时间来穿过第一和第二检测器倍增器电极之间的低电势场。这导致较高m/z离子种类的离子信号拖尾。用标准和改进的检测器几何形状（马肌红蛋白的单质子化分子离子种类）获得的离子信号的数值减法导致质量分辨率的改善，使得可以分辨新的加合物离子种类（来自三氟乙酸）。
The ion detection process in a discrete‐dynode electron multiplier can result in significant mass resolution losses in time‐of‐flight mass spectrometry (TOF‐MS) for higher mass‐to‐charge (m/z) ion species. This resolution loss is attributed to propagation time delays and signal broadening in the ion detector. This is presumed tobe due to the generation o a distribution of secondary ion species produced initially upon impact of a primary ion with the first ynoe surface of the ion detector. Comparisons are made between the signals produced by a standard discrete dynode ion detector (which amplified the negatively chqrged species produced by impact of a primry ion) and a detector modified to respond to only the positively charged secondary ion species produced by a primary ion impact. Ion signals for higher m/z ions with the standard detector geometry are see to be due to a narrow signal component, most likely due to the generation o secondary electrons and/or very low mass secondary ions (H−), and a broad signal component, apparently due to secondary ions which take signifiant amounts of time to traverse the low potential fields between the first and second detector dynode. This results in ion signal tailing for higher m/z ion species. Numerical subtraction of the ion signal obtained with the standard and modified detector geometries (singly protonated molecular ion species of equine myoglobin) results in an improvement in mass resolution, such that a new adduct ion species (from trifluoroacetic acid) can be resolved.