化学
分散性
分析化学(期刊)
低聚物
质谱法
飞行时间质谱
分辨率(逻辑)
萃取(化学)
摩尔质量分布
反射型
色谱法
聚合物
离子
电离
高分子化学
有机化学
人工智能
计算机科学
作者
Randy M. Whittal,David C. Schriemer,Liang Li
摘要
We report a polymer characterization study by matrix-assisted laser description/ionization (MALDI) on a linear time-of-flight instrument equipped with pulsed ion extraction for time-lag focusing. It is demonstrated that time-lag focusing MALDI provides improved mass resolution and mass accuracy over continuous extraction instruments. Oligomer resolution is extended to a much higher mass range than that observed even by continuous extraction reflectron systems. This allows new opportunities to study the chemical composition and determine the molecular weight of individual components in a mixture of higher molecular weight polymers. It is shown that oligomer resolution can be obtained for poly(ethylene glycol) (repeat unit mass of 44) of mass up to 25,000 u and poly(styrene) (repeat unit mass of 104) up to 55,000 u. Mass measurement accuracy of 80 ppm or better is demonstrated, and the relevance to end-group analysis is shown for two derivative of poly(ethylene glycol) used as slow-release drugs. The analysis of the molecular weight distribution was investigated at several extraction pulse potentials to determine if there was an effect on the relative peak area. We found that the values of the number-average molecular weight (Mn and the weight-average molecular weight (Mw) do not change significantly for a poly(styrene) blend with oligomer masses between 2,000 and 15,000 u and a polydispersity of 1.155. The values are within the 1.6% standard deviation observed for repeat analyses at the same extraction pulse.
科研通智能强力驱动
Strongly Powered by AbleSci AI