Atmospheric Pressure Interface for a Handheld Ion Trap Mass Spectrometer: Electrospray Ionization and Desorption Electrospray Ionization

摘要

Successful coupling of an atmospheric pressure ionization interface with a portable mass spectrometer (MS) is reported. This instrument has been tested with electrospray (ESI) and desorption electrospray ionization (DESI). Recent advances in portable MS instrumentation, coupled with ambient ionization techniques, have the potential to revolutionize in situ analysis. A considerable challenge, however, is the reduced pumping capacities of miniaturized pumps within, due to size and power consumption restrictions, and the simultaneous higher gas loads due to inlet apertures, solvent sprays, and sheath gases associated with atmospheric pressure ionization (API) techniques. Elegant future solutions might be found in high-performance miniature turbo pumps, but currently operation at elevated pressure and/or reduced inlet flow is required. A stainless steel capillary (10 cm length, 127 (mu)m i.d.) served as an atmospheric inlet and was installed on a Mini 10 handheld rectilinear ion trap mass spectrometer (22 lbs., 0.5 cu.ft., 75 W, Figure 1). Ions were directed down the axis of the ion trap through an aperture in the DC-biased endcap, which also acted as an ion gate. The gas flow rate into the vacuum chamber was measured as 11 mL/min, resulting in a pressure of 15 mtorr. Laboratory scale, custom built ESI and DESI sources were used to generate ions for transmission through the atmospheric pressure interface.