Portable linear ion trap mass spectrometer with compact multistage vacuum system and continuous atmospheric pressure interface

Abstract

A portable linear ion trap mass spectrometer featuring a compact three-stage vacuum system, a continuous atmospheric pressure interface (CAPI), and a miniature ion funnel was developed and characterized. The dimensions and weight of the instrument were 38 × 26 × 23 cm³ and ∼20 kg, respectively. The combination of a three-stage vacuum system and CAPI reduced the pressure smoothly from atmospheric to ∼5 × 10⁻⁴ Torr, ensuring that the miniature ion funnel, quadrupole ion guide, and linear ion trap operated in a suitable and stable vacuum environment. The analytical performance of the instrument was evaluated with a nano-electron spray ionization source and a reserpine sample solution. A satisfactory mass resolution up to 4060 (m/Δm, FWHM) was achieved at m/z 609 when the mass scan rate was 495 Da s⁻¹. Unit mass resolution was achieved at a mass scan rate of 6000 Da s⁻¹. In addition, a limit of detection of 5 ng mL⁻¹ was achieved and tandem mass spectrometry (MS₃) was successfully performed with the instrument. Furthermore, the measurements showed high repeatability and stability (RSD < 6%). This portable mass spectrometer shows great potential for practical applications in on-site analyses, such as those required for food safety, drug analysis, environmental protection, forensic investigations, and homeland security.