40 5977B Series MSD Troubleshooting and Maintenance Manual
2 General Troubleshooting
Chromatographic Symptoms
These are symptoms you may observe in the chromatograms generated by data
acquisition. In general, these symptoms do not prevent you from operating
your GC/MSD system. They indicate, however, that the data you are acquiring
may not be the best data obtainable. These symptoms can be caused by
instrument malfunctions, but are more likely caused by incorrect
chromatographic technique.
The following symptoms also apply to mass spectral data:
• If sensitivity is low
• If repeatability is poor
No peaks
If an analysis shows no chromatographic peaks, only a flat baseline or minor
noise, run one of the automated tune programs. If the MSD passes tune, the
problem is most likely related to the GC. If the MSD does not pass tune, the
problem is most likely in the MSD.
Passes tune
• Incorrect sample concentration
• No analytes present
• Syringe missing from the ALS, or not installed correctly
• Injection accidentally made in split mode instead of splitless mode
• Empty or almost empty sample vial
• Dirty GC inlet
• Leaking GC inlet
†
• Loose column nut at the GC inlet
†
† This could cause a fault condition in the GC that would prevent the GC
from operating.
Does not pass tune
• Calibration vial is empty
• Excessive foreline or analyzer chamber pressure
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