He L, Liu Y H, Zhu Y, Lubman D M
Department of Chemistry, University of Michigan, Ann Arbor 48109-1055, USA.
Rapid Commun Mass Spectrom. 1997;11(13):1440-8. doi: 10.1002/(SICI)1097-0231(19970830)11:13<1440::AID-RCM25>3.0.CO;2-9.
The detection of oligonucleotides has been studied using external injection of Matrix-assisted laser desorption/ionization (MALDI) produced ions into a quadrupole ion trap storage device. The ions stored in the trap are then detected by pulsed DC injection into a reflection time-of-flight mass spectrometer. It is shown that by using a low acceleration voltage from the probe tip and external injection into the trap that 3-mers to 9-mers can be stored for 20-50 ms and detected as intact ions. In comparison, direct MALDI inside the trap resulted in extensive fragmentation as a function of storage time. Using the external injection with a He buffer gas in the trap yields a resolution of 250-400 in the ion trap storage/reflectron time-of-flight mass spectrometer. The resolution can be further enhanced to 400-800 using a bipolar extraction method. In addition, the trapping efficiency for the injection of externally produced ions into the trap can be enhanced using a dynamic trapping method. The MALDI mass spectra produced by this methodology result in excellent signal-to-noise ratio due to the capabilities of the trap for eliminating low mass matrix background from the spectra.
已通过将基质辅助激光解吸/电离（MALDI）产生的离子外部注入四极离子阱存储装置来研究寡核苷酸的检测。然后，通过向反射式飞行时间质谱仪中脉冲直流注入来检测存储在阱中的离子。结果表明，通过使用来自探针尖端的低加速电压并将其外部注入阱中，3聚体至9聚体可以存储20 - 50毫秒，并作为完整离子被检测到。相比之下，阱内直接MALDI会导致随着存储时间的延长出现大量碎片化。在阱中使用带有氦缓冲气体的外部注入，在离子阱存储/反射式飞行时间质谱仪中可产生250 - 400的分辨率。使用双极提取方法，分辨率可进一步提高到400 - 800。此外，使用动态捕获方法可以提高将外部产生离子注入阱中的捕获效率。由于阱能够从光谱中消除低质量基质背景，这种方法产生的MALDI质谱具有出色的信噪比。
