Properly shutting down the HTEC will ensure preservation of functionality after a long hiatus (weeks to months).  Most issues dealing with improper storage are related to salt precipitates clogging lines when mobile phase dries out, or bacteria growth,  For proper shutdown of the HTEC-500/510, please follow the protocol below:

A. Remove the precolumn from the system and replace it with a two-way joint. Repack the precolumn

before the start of the next analysis. If using a GU-GEL column, remove the column from the system

and plug each end. If using another type of column, leave the separation column connected to

the system for now. All enzyme immobilized columns (reactors) need to be removed and stored in

an appropriate buffer and kept in a refrigerator.

B. Mobile phase in the whole system and in the separation column should be substituted with 30%

methanol in water. Methanol will prevent bacterial growth. Replace the mobile phase with 30%

methanol and aspirate some solution from the drain valve of the pump using a syringe so that the

mobile phase in the degasser is substituted with 30% methanol. Then set the position of the injector

to INJECT and let the 30% methanol flow for 1 hour through the line at 70% or 80% of the set flow rate

value. This value is specific to the type of separation column being used. During this process, switch

off the ECD. Take the drain just after the column and put a plug on the inlet tubing of the ECD to

prevent the ECD from drying out. Wash out the ECD content with the flow from the column after

washing the column for 1 hour. Connect the column back to the ECD and run the pump

continuously for another 10 min.

C. Disconnect the tubing from the waste bottle. Wash the piston using ultrapure

water from the pump wash port. Wash the ports of the manual injector using ultrapure water.

D. Unscrew the fixing nut at the reference electrode on the ECD cell and put the reference electrode

at 4°C keeping it’s tip in 1 M LiCl/0.1 M CH3COOH . This solvent is present in it’s cap.  If the original reference electrode cap is lost, please place in a vial with mobile phase wrapping with parafilm.  Other parts of the ECD will become dry.

E. Disconnect the separation column from the line and plug it at each end. Plug the free end of the

tubing with a tubing plug.

F. After these steps, the degasser, the pump, the injector and all the tubing are filled with 30%

methanol.