Fig. 4. Sketch of the vacuum system (upper) and its corresponding position in a schematic of API-MRTOF-MS (lower); the dotted and dashed rectangular frames with different colors indicate the four main chambers of the instrument: (1) MIR chamber, (2) RFQs and FLT chambers, (3) ST and DT chambers, (4) MRTOF analyzer chamber. Differential pumping stages and pressure in each compartment are present. The aperture diameters are presented in mm.
The API-MRTOF-MS apparatus is in the shape of the letter ā€œLā€ with a length of 2230 mm, coupled with ESI ionization on the left. Each chamber contains electrical feedthroughs, most of which are multi-feedthroughs, except those for the ultrahigh voltage supplies. Heating plaster containing the silicone heating sheet inside is utilized to cover both sides of the MRTOF analyzer chamber, which can maintain a maximum chamber temperature of 80 ā„ƒ to obtain a better vacuum. Table 1 lists the pressure of each chamber marked in Fig. 4, along with the pumping speed of the used pump. All turbo pumps are backed up by a 6 L/s roots pump (NeoDry 30E, Kashiyama).
Table 1 Chamber pressure with and without load