PNNL

Abstract

The resolving power of differential ion mobility spectrometry (FAIMS) was dramatically increased recently by the introduction of carrier gases comprising up to 75% He or various vapors, enabling many new applications. However, the gains were often at the expense of analysis speed, in particular making high-resolution FAIMS incompatible with online liquid-phase separations. Here, we report FAIMS employing hydrogen, specifically in mixtures with N2 containing up to 98.4% H2. Such compositions raise the mobilities of all ions and thus resolving power, while avoiding the electrical breakdown inevitable in He-rich mixtures. The increases of resolving power and ensuing peak resolution are especially significant at the greatest H2 fractions - above ~80 - 90%. Higher resolution can be exchanged for acceleration of the analyses by up to ~20 times. For more mobile species such as multiply-charged peptides, this exchange is presently forced by the constraints of existing FAIMS devices, but future designs optimized for H2 should consistently improve resolution for all analytes.