Portable Aerosol Mass Spectrometer with Enhanced Resolution

Rapid identification of pathogenic agents is essential for safeguarding against airborne threats, including bacteria, viruses, and toxins. Conventional bioaerosol detection systems typically utilize ultraviolet (UV) laser ionization of individual particles under high-vacuum conditions within the accelerator region of a time-of-flight (TOF) mass spectrometer. However, this method is hindered by particle size bias, limited throughput, and inadequate mass-resolving power and accuracy. In this work, we present a novel analytical strategy in which aerosol particle ionization and subsequent mass analysis are spatially separated. Enhanced chemical characterization of airborne particles is achieved by conducting laser ionization at elevated pressures (1-10 Torr) within an ion funnel, followed by ion transfer through an ion-guiding system for high-accuracy mass analysis using a compact orthogonal acceleration time-of-flight (oaTOF) mass spectrometer. The system operates with only two small pumps to maintain the necessary vacuum conditions. This design achieves an improvement of about 1 order of magnitude in mass-resolving power compared to standard instruments of similar size. High-quality mass spectra of an aerosol sample can be collected in under 10 s, with detection sensitivity as low as ∼1 attomole of biological material. Furthermore, the system permits the selective removal of noninformative low-mass ions prior to entry into the oaTOF mass analyzer, thereby enhancing analytical performance.