Masked Multiplexed Separations to Enhance Duty Cycle for Structures for Lossless Ion Manipulations

The
experimental paradigm of one ion packet release per spectrum
severely hinders throughput in broadband ion mobility spectrometry
(IMS) systems (e.g., drift tube and traveling wave systems). Ion trapping
marginally mitigates this problem, but the duty cycle deficit is amplified
when moving to high resolution, long pathlength systems. As a consequence,
new multiplexing strategies that maximize throughput while preserving
peak fidelity are essential for high-resolution IMS separations [e.g.,
structures for lossless ion manipulations (SLIMs) and multi-pass technologies].
Currently, broadly applicable deconvolution strategies for Hadamard-based
ion multiplexing are limited to a narrow range of modulation sequences
and do not fully maximize the ion signal generated during separation
across an extended path length. Compared to prior Hadamard deconvolution
errors that rely upon peak picking or discrete error classification,
the masked deconvolution matrix technique exploits the knowledge that
Hadamard transform artifacts are reflected about the central, primary
signal [i.e., the true arrival time distribution (ATD)]. By randomly
inducing mathematical artifacts, it is possible to identify spectral
artifacts simply by their high degree of variability relative to the
core ATD. It is important to note that the deweighting approach using
the masked deconvolution matrix does not make any assumptions about
the underlying transform and is applicable to any multiplexing strategy
employing binary sequences. In addition to demonstrating a 100-fold
increase in the total number of ions detected, the effective deconvolution
of data from 5, 6, 7, and 8-bit pseudo-random sequences expands the
utility and efficiency of the SLIM platform.