Thermo Scientific ISQ 7000 Hardware Manual page 155

Possible Remedies
You may have a leak that is allowing solvent vapors to get into the ISQ 7000 instrument. Use a spray gas, such as Tetrafluoethane, to
check for leaks and then fix them. See
Optimize the GC method to separate the solvent peak from the area of interest in the chromatogram. The following compounds may have
been introduced during sample injection, a cleaning or autosampler rinsing solvent. The following commonly used solvents have ions at
the listed m/z:
• Acetone (m/z 43, 58, 59)
• Hexane (m/z 41, 43, 56, 57, 58, 85, 86)
• Isooctane (m/z 57, 99)
• Methanol (m/z 31)
• Methylene chloride (m/z 84/83)
• Toluene (m/z 91, 92)
• Trichloroethane (m/z 151, 153)
• Xylene (m/z 105, 106)
Table 3. Common Contaminants
Ions (m/z) To Monitor
13, 14, 15, 16, 17, 29, 41, 57
18, 28, 32, 44 or 14, 16, 19
69, 100, 119, 131, 169, 181, 214, 219,
264, 376, 414, 426, 464, 502, 576, 614
31
43, 58
78
91, 92
105, 106
151, 153
149
Peaks spaced 14 amu apart
Thermo Scientific
Investigating Vacuum Issues
Compound
Methane
H2O, N2, O2, CO2 or N, O
PFTBA and related ions
Methanol
Acetone
Benzene
Toluene or xylene
Xylene
Trichloroethane
Plasticizer (phthalates)
Hydrocarbons
for details.
Possible Source
CI gas
Residual air and water, air leaks,
outgassing from Vespel ferrules
PFTBA (tuning compound)
Cleaning solvent
Cleaning solvent
Cleaning solvent
Cleaning solvent
Cleaning solvent
Cleaning solvent
Use of vinyl or plastic gloves
Fingerprints, foreline pump oil, or other
hydrocarbons
2
Troubleshooting
Investigating Contamination Issues
ISQ 7000 Hardware Manual 127