In situ Rb-Sr dating by collision cell, multicollection inductively-coupled plasma mass-spectrometry with pre-cell mass-filter, (CC-MC-ICPMS/MS).

We document the utility for in situ Rb-Sr dating of a one-of-a-kind tribrid mass spectrometer, ‘Proteus’, coupled to a UV laser ablation system. Proteus combines a pre-cell quadrupole mass-filter,collision cell,...

Low-Vacuum Quadrupole Mass Filter Using a Drift Gas

Performing mass spectrometry in a low-vacuum environment can markedly reduce the cost, size, and power consumption of instrumentation by reducing the workload of the pumping system. Under a low-vacuum environment, ions in a quadrupole mass filter do not have sufficient kinetic energy in the axial direction to reach the detector for mass analysis. To resolve this problem and develop a mass spectrometer suitable for a low-vacuum environment, a mass analysis method is proposed where a drift gas is used to supply energy to the ions. A simulation model was constructed in COMSOL Multiphysics, and a simple experimental device was built to validate the proposed method. The simulation results showed that this method effectively solves these problems, and the obtained spectral peak was superior to that without drift gas flow regarding spectral peak intensity and width. The experimental results showed that the proposed method separated ions with different mass-to-charge ratios at a pressure of 20 Pa. This work provides a theoretical foundation for the development of low-vacuum mass spectrometry, which will promote portability, provide a lower threshold of use, and expand the fields of application for mass spectrometers.

Dynamic Range Expansion by Gas-Phase Ion Fractionation and Enrichment for Imaging Mass Spectrometry

In the analysis of biological tissue by imaging mass spectrometry (IMS), the limit of detection and dynamic range are of paramount importance in obtaining experimental results that provide insight into underlying biological processes. Many important biomolecules are present in the tissue milieu in low concentrations and in complex mixtures with other compounds of widely ranging abundances, challenging the limits of analytical technologies. In many IMS experiments, the ion signal can be dominated by a few highly abundant ion species. On trap-based instrument platforms that accumulate ions prior to mass analysis, these high abundance ions can diminish the detection and dynamic range of lower abundance ions. Herein, we characterize two strategies for combating these challenges during IMS experiments on a hybrid QqFT-ICR MS. In one iteration, the mass resolving capabilities of a quadrupole mass filter are used to selectively enrich for ions of interest via a technique previously termed continuous accumulation of selected ions (CASI). Secondly, we have introduced a supplemental dipolar AC waveform to the quadrupole mass filter of a commercial QqFT-ICR mass spectrometer to perform selected ion ejection prior to the ion accumulation region. This setup allows the selective ejection of the most abundant ion species prior to ion accumulation, thereby greatly improving the molecular depth with which IMS can probe tissue samples.<br>

Dynamic Range Expansion by Gas-Phase Ion Fractionation and Enrichment for Imaging Mass Spectrometry

In the analysis of biological tissue by imaging mass spectrometry (IMS), the limit of detection and dynamic range are of paramount importance in obtaining experimental results that provide insight into underlying biological processes. Many important biomolecules are present in the tissue milieu in low concentrations and in complex mixtures with other compounds of widely ranging abundances, challenging the limits of analytical technologies. In many IMS experiments, the ion signal can be dominated by a few highly abundant ion species. On trap-based instrument platforms that accumulate ions prior to mass analysis, these high abundance ions can diminish the detection and dynamic range of lower abundance ions. Herein, we characterize two strategies for combating these challenges during IMS experiments on a hybrid QqFT-ICR MS. In one iteration, the mass resolving capabilities of a quadrupole mass filter are used to selectively enrich for ions of interest via a technique previously termed continuous accumulation of selected ions (CASI). Secondly, we have introduced a supplemental dipolar AC waveform to the quadrupole mass filter of a commercial QqFT-ICR mass spectrometer to perform selected ion ejection prior to the ion accumulation region. This setup allows the selective ejection of the most abundant ion species prior to ion accumulation, thereby greatly improving the molecular depth with which IMS can probe tissue samples.<br>