30
HTEC-500
15.
Troubleshooting
(Please refer to these points after reading chapter 1-14)
When you discover a problem, you need to find out which part is affected, the HPLC-ECD, the
autosampler or the sample itself. Please use the manual injector of the HTEC-500 to inject samples and
only inject standard samples to diagnose the problem at first. Do not use the autosampler to diagnose
the problems listed below. Once you find that the HTEC-500 is OK, please start to use the autosampler
again.
No peak appears even though a sample was injected. Possible causes are as follows:
• Chromatogram time setting is too short.
• The drain port of the injector is blocked and sample is not loaded into the sample loop.
• The pump doesn’t work. A potential cause is that an air bubble may be present (see chapter 8,
page 11).
• The ECD is switched off.
• There is no connection between the “integrator out” of the HTEC-500 and the EPC-500 or other
integrators.
• There is no signal input from the “auto zero”.
• The background current is too high.
• The precolumn is very contaminated.
The pump is unstable or has frequent errors. Possible causes are as follows:
• Refer to chapter 7, page 8.
• The injector works too slowly or it’s not used in the designated way.
• The precolumn is very contaminated.
The background current increases gradually over several hours or stays high. Possible causes
are as follows:
• The separation column and/or precolumn are new. Please wash the columns with clean analytical
mobile phase overnight.
• The wrong mobile phase conditioning was used. Please check the pH of the mobile phase. Do not dip
a pH probe into the bottle. Take some of the mobile phase in a small vial and use the pH probe to
check the pH.
• A reagent in the mobile phase is not suitable or the ultrapure water has been contaminated. Eicom
recommends specific brands for specific reagents, especially for methanol, SDS and SOS.
• The mobile phase is too old.
• The precolumn/separation column is contaminated. Use Eicom brand columns.
• The reference electrode is old.
• The working electrode is covered by contamination.
• The graphite electrode was applied under a methanol-rich condition.
• The mobile phase was not shaken well before being set up on the HPLC.
• The mobile phase that was used for the previous analysis still remains in the degasser. Use a syringe to
aspirate solution from the drain valve of the pump so that the old mobile phase flows out. Disconnect
the column and wash the line using clean mobile phase or ultrapure water.
A big unknown peak appears. Possible causes are as follows:
• The sample injected before the current analysis contained a high concentration of a hydrophobic
substance that was detected by the ECD. For example, sample refinement such as aluminum
adsorption can be applied in the case of catecholamine analysis to help with this problem.
