A Planar Integrated Micro-mass Spectrometer - LC-MS in Drug Bioanalysis - page 441

Table 1 Pressure regimes for stable operation of the PIMMS

Gas fl ow
(m L/min)

Gas supply
pressure, p g (Pa)

Capillary
pressure, p V (Pa)

Chamber
pressure, p 0 (Pa) Chamber Mode

Plasma Ignition 1,000 1.5 × 10 5 6 × 10 4 900

Operation 100 1.5 × 10 5 2 × 10 4 100

Ionization Operation 45 1 × 10 5 1 × 10 4 15

Fig. 16 Pressure in the chamber vs. inlet pressure; capillary: length, 10 cm; diameter, 100 m m;
aperture size A , 2 × 40 × 300 m m ²

By de fi ning:

4

·
128· ·

π d

K =

c

η l

the pressure p 0 results:

2

AK · AK ·

⎛ ⎞

g g

2

p =− + − p .

⎜ ⎟

0 v

K K

⎝ ⎠

c c

In Fig. 16 the result of the pressure drop model for the chosen geometry is shown.
In this curve only the 10 cm long capillary is considered, since that is the point
where p v is defined at according to Fig. 15 .