数字离子阱质谱仪低质量截止值的改进方法

Improvement of Low Mass Cutoff Effect Using Digital Ion Trap Technology

本研究在实验室自制的线形数字离子阱质量分析器上,通过改变数码电源的频率扫描方式,在CID过程中,通过扫描数字束缚方波电源的频率和数字激发方波的频率实现母体解离。例如对于利血平母体离子,当将离子数字束缚方波频率从500 kHz扫描到560 kHz,可以测量到低质荷比的碎片离子,成功实现了串级质谱分析的低质量碎片离子的分析。通过与利血平三重四极质谱串级质谱分析实验结果的比较,发现可以在数字离子阱质谱仪上获得与三重四极质谱相同的串级质谱测量结果。结果表明,本方法可以用于低质量离子的测量,克服了传统离子阱质谱进行串级质谱分析的一个主要难点,显著提高数字离子阱质谱的性能。

The low mass cutoff（ LMCO） is the main weakness of ion trap when it performs tandem mass analysis by collision induced dissociation（ CID）. LMCO means that some daughter ions of m / z are less than about 1 /3 of the m / z of parent ion could not be detected during the tandem mass spectrometry processing. A new method which can significantly improve the effect of low mass cutoff was proposed and investigated. By simply changing the scan method of digital potential frequency,some low mass ions can be effectively observed during the tandem mass spectrometric experiment. In the experiment,the frequency of the digital ion trapping power and ion activation power were scanned from lower value to higher value,and some lower mass product ions could be detected during CID process. For example,some lower mass ions were observed during the CID of reserpine precursor ion when the frequency of its digital trapping power was scanned from 500 kHz to 560 kHz. The tandem mass spectra of Reserpine ion showed that the experimental results both from this work and the triple quadrupole mass spectrometer were exactly the same.