Influence of Pseudopotential Well Depth on the Performance of Hybrid Linear Ion Trap/Time-of-Flight Mass Spectrometry Driven by Square and Sinusoidal Waveform.

Abstract

Quadrupole devices are widely used as ion analyzers and ion guides, which are usually driven by a sinusoidal waveform. Recently, these devices driven by a digital waveform have attracted much attention. Driven by different rf waveforms, the pseudopotential well depth of quadrupole devices is significantly different, which will affect their performance. However, there is a lack of comprehensive view on the performance differences of quadrupole devices or hybrid instrument driven by different rf waveforms. In this paper, the differences in mass range, resolution, sensitivity, and ion fragmentation of LIT/TOFMS driven by square and sinusoidal waveforms were investigated. Compared with the sinusoidal mode, the square mode had a wider mass range and better mass resolution. Toluene was used to study the difference in sensitivity and ion fragmentation between the two modes. The results showed that the sensitivity of the square mode was 1.7-2.5 times that of the sinusoidal mode at different ion densities. According to the sensitivity differences, it was inferred that the ion-trapping efficiency and ion capacity of LIT in the square mode were 2.0 times and 1.7 times those in sinusoidal mode. It was found that the square mode behaved "softer" and presented less fragmentation, and the proportion of fragment ions in the sinusoidal mode can reach 3.2 times that in the square mode at high ion density. Therefore, LIT/TOFMS driven by a square waveform shows greater potential in the application of the complex matrix system with a wide mass range.