Trapped ion mobility spectrometry: A short review

Trapped ion mobility spectrometry (TIMS) hybridized with mass spectrometry (MS) is a relatively recent advance in the field of ion mobility mass spectrometry (IMMS). The basic idea behind TIMS is the reversal of the classic drift cell analyzer. Rather than driving ions through a stationary gas, as in a drift cell, TIMS holds the ions stationary in a moving column of gas. This has the immediate advantage that the physical dimension of the analyzer can be small (∼5 cm) whereas the analytical column of gas – the column that flows past during the course of an analysis – can be large (as much as 10 m) and user defined. In the years since the first publication, TIMS has proven to be a highly versatile alternative to drift tube ion mobility achieving high resolving power (R ∼ 300), duty cycle (100%), and efficiency (∼80%). In addition to its basic performance specifications, the flexibility of TIMS allows it to be adapted to a variety of applications. This is highlighted particularly by the PASEF (parallel accumulation serial fragmentation) workflow, which adapts TIMS-MS to the shotgun proteomics application. In this brief review, the general operating principles, theory, and a number of TIMS-MS applications are summarized.