Using Digital Waveforms to Mitigate Solvent Clustering During Mass Filter Analysis of Proteins.

With advances in the precision of digital electronics, waveform generation technology has progressed to a state that enables the creation of m/z filters that are purely digitally driven. These advances present new methods of performing mass analyses that provide information from a chemical system that are inherently difficult to achieve by other means. One notable characteristic of digitally driven mass filters is the capacity to transmit ions at m/z ratios that vastly exceed the capabilities of traditional resonant systems. However, the capacity to probe ion m/z ratios that span multiple orders of magnitudes across multiple orders of magnitude presents a new set of issues requiring a solution. In the present work, when probing multiply charged protein species beyond m/z 2000 using a gentle atmospheric pressure interface, the presence of solvent adducts and poorly resolved multimers can severely degrade spectral fidelity. Increasing energy imparted into a target ion population is one approach minimizing these clusters; however, the use of digital waveform technology provides an alternative that maximizes ion transport efficiency and simultaneously minimizes solvent clustering. In addition to the frequency of the applied waveform, digital manipulation also provides control over the duty cycle of the target waveform. This work examines the conditions and approach leading to optimal digital waveform operation to minimize solvent clustering. Graphical Abstract ᅟ.