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HTEC-500
14.
Regular Maintenance Schedule
Daily Maintenance
Washing the Port of the HPLC Pump
Each time the system is shut down or before running the system, flush the pump piston washing port with
2-3 ml of ultrapure water through the attached syringe. This is required in order to flush out, and prevent
crystallization of, any mobile phase present. Do not force water in with the syringe if any back pressure is
felt. This may lead to a leakage in the washing line.
Occasional Maintenance
(typically required once or twice per month)
Working Electrode
If the ECD background current is unusually high or low (ideal range is between 5 to 15 nA), please wipe
the smooth surface of the working electrode with 100% acetone using a Kimwipe. This will remove
pollution that is considered to be hydrophobic substances on the surface. The source of this pollution
can be the mobile phase, samples and/or columns. If you need to wipe it frequently (once a week or
more), please check if the mobile phase ingredients and your sample preparation protocol match with
the requirements shown in the Eicom user’s manuals. If you find that the installed gasket is dusty or the
edge of it is not clearly cut, please replace it immediately. If you are using a graphite electrode and it
has been exposed to more than 35% methanol or 15% acetonitrile, please change it.
Precolumn
(The following steps should be carried out after 50 homogenate sample injections or 500 microdialysis
sample injections.)
If you find odd-shaped peaks, it may be time to repack the precolumn. To judge the quality of the
precolumn, remove it and connect a separation column directly to the injector. Following this, inject a
standard sample. If the peak now has a good shape, it indicates that the precolumn is contaminated.
The sample capacity of a precolumn is dependent on the sample type and its preparation. The
guideline mentioned above is only for reference. The packing materials and size of the precolumns vary
depending on the application. Please see the corresponding user’s manual provided by Eicom.
If you are using the PP-ODS column, the precolumn should be installed before the injectors. In this case,
the quality of the precolumn is difficult to judge. Therefore, please repack the precolumn every month.
Yearly Maintenance
(For acetylcholine analysis, every 6 months)
Reference Electrode
Change the reference electrode once a year regardless of its usage (if you have been keeping the
reference electrode on a shelf with it’s tip dipped in LiCl solution, you can use the electrode for another
year). The date of production is printed on the electrode (for example, 0805 means May 2008). In the
case of acetylcholine analysis, the lifetime of the reference electrode is only 6 months. Sometimes,
verifying the quality of the reference electrode is difficult. A decayed reference electrode may lead to
misdiagnosis of problems with the HTEC-500. The rate of decay of the reference electrode accelerates
after one year. Therefore, please change the electrode periodically even if the system works without
significant problems.
