Application of a Gradient-Threaded Discrete Twisted Dipole Ion Guide (GTDIG) for High-Efficiency Ion Propulsion and an Expanded <i>m</i> / <i>z</i> Bandwidth in Mass Spectrometry

In mass spectrometry (MS), the radio frequency (RF)-only multipole ion guide commonly used in a medium pressure range (0.1-10 Pa) is susceptible to a collision-damping-induced loss of instrumentation sensitivity, resulting in operation within a limited <i>m</i>/<i>z</i> bandwidth. In this study, a novel direct current (DC)-free gradient-threaded discrete twisted dipole ion guide (GTDIG) is proposed for high-efficiency ion propulsion and an expanded <i>m</i>/<i>z</i> bandwidth in a medium vacuum (0.1-10 Pa). An overview of the GTDIG working principles is provided with systematic optimization of the critical parameters. The GTDIG has been applied by using a series of printed circuit boards, utilizing an innovative discrete helical electrode design. The performance of the GTDIG prototype is evaluated using multiphysical numerical modeling and tested using a custom-built nanoelectrospray ionization (ESI)-MS platform, including a direct comparison with a quadrupole ion guide. The results indicate that the RF-only GTDIG offers a significantly larger <i>m</i>/<i>z</i> window while effectively maintaining an axial field, demonstrating that this concept can be utilized in the development of instruments with an enhanced performance.