General Troubleshooting 2
Troubleshooting and Maintenance Manual 29
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/MS 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.
Two of the symptoms, Low sensitivity and Poor repeatability also apply to
mass spectral data.
No peaks
If an analysis shows no chromatographic peaks, only a flat baseline or minor
noise, run the automated tune program. If the MS passes tune, the problem is
most likely related to the GC. If the MS does not pass tune, the problem is most
likely in the MS.
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
• Ver y dirty ion source
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