2000 MS Hardware Maintenance
154
Troubleshooting of Diffusion Pump System
Common Contaminant
Ions (m/z)
Compound Possible
Source
18, 28, 32, 44
H
2
O, N
2
, O
2
, CO
2
Air
Leak
69
,
131
, 219, 264, 414, 464,
502, 614
PFTBA
Leaking Calibration Valve
31, 32
Methanol
Cleaning Solvent
43, 58
Acetone
Cleaning Solvent
73
, 147,
207
, 221,
281
, 355,
429
Dimethylpolysiloxane
Septum or methyl silicone
column coating
77, 92, 115,128,141,
168,184, 223, 233, 260,
354
,
446
Diffusion Pump Fluid
Diffusion Pump Fluid
149 Plasticizer
(Phthalates)
Vacuum seals damaged by high
temperature.
Solvent Bottle Contamination
Groups of peaks spaced 14
u apart
Hydrocarbons
Foreline pump oil, fingerprints,
saturated trap pellets
77, 141, 169, 204
1-chloro-3-
phenoxybenzene
Pump oil degassing
contamination
146, 148, 111
Dichlorobenzene
Pump oil degassing
contamination
NOTE: Numbers
in
bold
denote masses more useful for identifying
contaminants.