ISQ User Guide - Write Frame of Mind

8 Troubleshooting
How to Know When Your System Needs Maintenance
How to Know When Your System Needs Maintenance
Typically, you will notice that your instrument needs maintenance when you are analyzing
your data on the computer. Some of the most common reasons and indications are as follows:
• Contamination—If you notice excessive background in your mass spectra, it is usually an
indication that your instrument is contaminated. Use the mass spectrum in the table
below to understand the origin of the contamination. If you notice cleaning solvent
peaks, it is usually an indication that your ion source cartridge was installed before it was
completely dried.
• Fingerprints—If you notice a series of mass peaks in your data that are 14 amu apart, it is
usually an indication of fingerprint or other hydrocarbon contamination. To avoid
fingerprints, you should wear clean, lint-free gloves when performing any type of
maintenance on a component in the vacuum manifold of the ISQ.
• Air Leaks—If you notice a higher than normal vacuum pressure or poor sensitivity, it is
usually an indication of an air leak. Check the last o-ring or ferrule you installed.
Table 1. Common Contaminants
Ions (m/z) To Monitor Compound Possible Source
13,14,15,16 Methane CI gas
18, 28, 32, 44 or 14, 16 H2O, N2 , O2 , CO2 or N, O Residual air and water, air leaks,
outgassing from Vespel ferrules
31, 51, 69, 100, 119, 131, 169, 181,
214, 219, 264, 376, 414, 426, 464,
502, 576, 614
PFTBA and related ions PFTBA (tuning compound)
31 Methanol Cleaning solvent
43, 58 Acetone Cleaning solvent
78 Benzene Cleaning solvent
91, 92 Toluene or xylene Cleaning solvent
105, 106 Xylene Cleaning solvent
151, 153 Trichloroethane Cleaning solvent
149 Plasticizer (phthalates) Use of vinyl or plastic gloves
Peaks spaced 14 amu apart Hydrocarbons Fingerprints, foreline pump oil or other
hydrocarbons
90 ISQ User Guide Thermo Scientific