Chromatographic Troubleshooting
Baseline symptoms
Spiking
Spikes are isolated baseline disturbances, usually as sudden (and large) upscale movements. If accompanied by noise, the noise problem should be solved first, since spiking may disappear at the same time.
1.Spikes appear whenever the chart is running:
C The cause is almost always electronic in origin: Loose connections are likely. Check signal cable connections at the detector and controller ends.
C A dirty slidewire on a recorder may cause this; see the maintenance section of your recorder manual.
C Loose or dirty contacts between printed circuit boards and their connectors may be responsible. Read appropriate sections regarding servicing boards and connectors for the HP 5890.
2.Spikes appear on chromatograms but not when the recorder is isolated (no input signal):
C This indicates a detector problem: In extremely dirty FID collectors, particles may break away, causing disturbances in the most sensitive area of the detector. This appears on the chart as a spike.
C A less common cause is column packing particles being blown into the detector: A loose or inadequate glass wool plug at the detector end of the column may fail. As particles are blown through the detector, the disturbance generates a spike. This may happen with any detector, but FIDs and NPDs are particularly susceptible because of the narrow bore of the jet.
The bottom of the jet in FIDs and NPDs extends into the end of a packed column. If the bottom touches the glass wool plug at the end of the packing, spikes are produced.
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