Chemistry Department, Indiana University, Bloomington, Indiana 47401, USA.
Anal Chem. 2011 Feb 1;83(3):950-6. doi: 10.1021/ac102633p. Epub 2011 Jan 12.
A novel image charge detection mass spectrometer (CDMS) with improved sensitivity and mass accuracy is described. The improved detector design and method of data analysis allow us to measure a reliable mass for a single macroion that is an order of magnitude smaller than previously achieved with CDMS. The apparatus employs an image charge detector array consisting of 22 detectors. The detectors are divided into two groups that can be floated at different potentials. The signals from the detector array are analyzed using a correlation approach to yield the velocities in the two groups of detectors and the charge. These quantities, together with the voltage difference between the two groups of detectors, provide a value for the mass. The mass, m/z, and charge distributions recorded for 300 kDa poly(ethylene oxide) (PEG) are presented. The mass distribution shows a peak at around 300 kDa with a width close to that expected from the polymer size distribution. In addition, there are broad peaks in the mass distribution at around 100 and 500 MDa. The 300 kDa ions have m/z ratios of ∼2 kDa/e, and the 100 and 500 MDa ions have m/z ratios of ∼40 kDa/e. The 100 and 500 MDa ions probably result from PEG aggregates that are either present in solution or the residue of large electrospray droplets.
一种新型的基于感应电荷检测的质谱仪（CDMS），具有更高的灵敏度和质量精度。改进的探测器设计和数据分析方法使我们能够测量单个大分子的可靠质量，其大小比以前使用 CDMS 所能达到的量级小一个数量级。该仪器采用由 22 个探测器组成的感应电荷探测器阵列。探测器分为两组，可以浮动在不同的电位下。探测器阵列的信号使用相关方法进行分析，以得出两组探测器中的速度和电荷。这些量以及两组探测器之间的电压差提供了质量的值。我们给出了 300 kDa 聚环氧乙烷（PEG）的质量、m/z 和电荷分布的记录。质量分布在约 300 kDa 处出现一个峰值，宽度接近聚合物尺寸分布的预期值。此外，在质量分布中还有约 100 和 500 MDa 的宽峰。300 kDa 离子的 m/z 比约为 2 kDa/e，而 100 和 500 MDa 离子的 m/z 比约为 40 kDa/e。100 和 500 MDa 离子可能来自于溶液中存在的 PEG 聚集物或大电喷雾液滴的残留物。
