Ion Guide Auxiliary Electrodes for Faster DMS-MS COV Switching
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Solution Overview
Problem
Conventional differential mobility spectrometry (DMS) systems face limitations in duty cycle and data point collection due to significant pauses between applying different compensation voltage (COV) values, which reduces the efficiency of ion analysis in applications like liquid chromatography (LC).
Innovation Solution
The implementation of an ion guide with a multipole rod set and auxiliary electrodes that apply a DC voltage to generate an axial electric field, allowing for reduced pause durations between transmitting ions with different COV values, thereby enhancing the duty cycle and enabling a wider COV range or smaller step sizes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If significant pauses are provided between applying different COV values to avoid cross-talk between ion groups, then ion transmission purity is improved, but the duty cycle decreases and productivity is reduced
Solution Approach 1:
An ion guide is introduced as an intermediary component between the DMS device and the mass analyzer. The ion guide uses auxiliary electrodes to generate an axial electric field that actively manipulates ion trajectories, enabling rapid clearing of residual ions from the previous COV setting before the next ion group is transmitted. This mediator allows the system to maintain ion transmission purity without requiring long pause periods, thereby improving the duty cycle.
2Productivity
If pause duration between transmitting ions with different COV values is reduced to improve duty cycle, then productivity is improved, but ion transmission purity may deteriorate due to increased cross-talk
Solution Approach 1:
The auxiliary electrodes in the ion guide perform preliminary action by generating an axial electric field that actively removes or redirects residual ions from the previous COV setting before the next ion group arrives. This preliminary clearing action ensures that even with reduced pause durations, cross-talk between different ion groups is minimized, maintaining ion transmission purity while allowing faster cycling through COV values.
3Measurement precision
If a wider COV range or smaller step sizes is used to improve measurement precision, then data point quality is improved, but the time required for complete analysis increases
Solution Approach 1:
The ion guide enables continuous operation by eliminating the need for extended pause periods between COV value changes. The auxiliary electrodes continuously manage ion trajectories throughout the transition between different COV settings, allowing the system to maintain a steady state of ion transmission. This continuity allows for wider COV ranges and smaller step sizes to be implemented without proportionally increasing total analysis time, as the ion guide efficiently handles the increased number of transitions.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach significantly improves the duty cycle of differential mobility spectrometry-MS analysis, enabling the collection of more data points on the LC time scale, and allowing for more precise ion analysis without increasing contamination or cross-talk.
Implementation Method 1
a DC voltage to be applied to the auxiliary electrodes while transmitting the first and second plurality of ions through the ion guide so as to generate an axial electric field along a longitudinal axis of the ion guide
Implementation Method 2
differential mobility spectrometry in which a differential mobility spectrometer separates ions on the basis of an alpha parameter, which is related to the differences in the ion mobility coefficient in varying strengths of electric field
Implementation Method 3
A DC potential, commonly referred to as a compensation voltage (COV or also CV), is applied to the differential mobility spectrometer and provides a counterbalancing electrostatic force to that of the SV
Data Source
AI summary
Methods and systems for performing differential mobility spectrometry-mass spectrometry (DMS-MIS) are provided herein. In various aspects, methods and systems described may be effective to improve the performance of a differential mobility spectrometry device and a MS device operating in tandem relative to conventional systems for DMS-MS. In certain aspects, methods and systems in accordance with the present teachings utilize an ion guide which comprises a multipole rod set and a plurality of auxiliary electrodes to which a DC voltage is applied during transmission of ions through the ion guide so as to generate an axial electric field along a longitudinal axis of the ion guide to accelerate the ions toward the outlet end of the ion guide. This may significantly reduce a pause duration between the application of different compensation voltage values without substantially increasing the likelihood of contamination or cross-talk between groups of ions transmitted by the differential mobility spectrometry device at each compensation voltage value.