Improved Sensitivity and Mass Range in Time-of-Flight Bioaerosol Mass Spectrometry Using an Electrostatic Ion Guide

Bioearosol mass spectrometry (BAMS) analyzes single particles in real time from ambient air, placing strict demands on instrument sensitivity. Modeling of the BAMS reflectron time of flight (TOF) with SIMION revealed design limitations associated with ion transmission and instrument sensitivity at higher masses. Design and implementation of a BAMS linear TOF with electrostatic ion guide and delayed extraction capabilities has greatly increased the sensitivity and mass range relative to the reflectron design. Initial experimental assessment of the new instrument design revealed improved sensitivity at high masses as illustrated when using standard particles of cytochrome C (m/z ∼ 12,000), from which the compound's monomer, dimer (m/z ∼ 24,000) and trimer (m/z ∼ 36,000) were readily detected.