FIGS. 3B, 3C, 4B, 4C and 4D illustrate examples of ESI devices 20 sealed directly to the mass spectrometer 10 (e.g., wall 12w of the vacuum chamber 12 holding the mass analyzer 30) with a respective discharge end with emitter 20e inside the high pressure vacuum chamber 12 holding the mass analyzer 30 to directly discharge (e.g., electrospray) ions into high pressure without requiring the inlet device 15 shown in FIGS. 3A, 4A, for example.
FIGS. 1, 2, 3A, 4A, 4D, 5A and 5B, for example, illustrate that the ESI device 20 can be a fluidic microchip 20c. However, as noted above, other ESI devices 20 may be used. FIGS. 3B, 3C, 4B, and 4C illustrate a capillary tip 20t as the ESI emitter 20e. The emitter 20e is inside the high pressure vacuum chamber 12 with the mass analyzer 30 rather than at atmospheric pressure. In some embodiments, the at least one emitter 20e can reside between about 1 mm to about 50 mm, more typically between about 1 mm and 20 mm. The distance can be about 1 mm, about 2 mm, about 3 mm, about 4 mm, about 5 mm, about 6 mm, about 7 mm, about 8 mm, about 9 mm, about 10 mm, about 11 mm, about 12 mm, about 13 mm, about 14 mm, about 15 mm, about 16 mm, about 17 mm, about 18 mm, about 19 mm, and about 20 mm, about 25 mm, about 30 mm, about 35 mm, about 40 mm, about 45 mm or about 50 mm from an ion entry aperture/electrode of the mass analyzer 30.
