Shutdown
Mobile phases are corrosive. Turning off an LC system without carefully removing the mobile phase from the pump, tubing, and detectors will result in corrosion and microbiological contamination. Follow these instructions to prepare your epsilon system for idle periods.
If the system will be used every day, or every few days, leave it running. It will then be ready and equilibrated when you wish to use it. Electrochemical detectors are solid-state devices ” they do not get used up with use. (Lamps in UV-Vis and fluorescence detectors should be turned off, however.) Pump seals generally last longer if the pump is kept running than if it is repeatedly started and stopped, so leave the pump running as well.
For inactive periods of a week or more, we recommend that the system be flushed clean of mobile phase salts and disassembled as follows:
EC DETECTOR
THE DETECTOR CAN BE DAMAGED IF YOU TOUCH LIVE CELL LEADS ” BE SURE TO TURN THE CELL OFF BEFORE DISCONNECTING!
Use the following sequence to properly shut down the detector:
- Turn the detectors off using the STOP button in either the RUN STATUS box or the EC SCHEDULE.
- Flush the pump, column, and flowcell with 40:60 acetonitrile:water.
- Disconnect the cell leads from the electrodes.
- Remove the working electrode, rinse with methanol, dry with a lab tissue, and store it in it's plastic box.
- Remove the reference electrode, rinse with deionized water, and store in 3 M NaCl.
- Remove the thin-layer gasket, rinse with deionized water and dry it.
- Wipe the auxiliary electrode with methanol and dry it.
PUMP
THESE INSTRUCTIONS ASSUME THAT THE COLUMN CAN BE STORED IN 40:60 ACETONITRILE:WATER. IF THIS IS NOT THE CASE, REMOVE THE COLUMN BEFORE FLUSHING THE PUMP.
Proceed as follows to flush out the mobile phase:
- Turn the detector off.
- Replace the mobile phase with 40:60 acetonitrile:water.
- Purge the pump with at least 20 mL to remove the old mobile phase.
- Pump through the entire system (injector, column, flowcell) for at least 15 minutes.
- Stop the pump and allow the pressure to decrease to 0 psi.
- Flush deionized water through any irrigation holes and around the pump heads.
- Remove the column and cap it for storage.
- Follow the instructions for disassembling the flowcell.
COLUMN
In most cases the column can be simultaneously flushed along with the pump. But if the column manufacturer recommends storage in some other solvent, follow those recommendations.
Be careful to separate incompatible solvents. If the column is to be stored in 100% organic solvent, flush out the mobile phase with 40:60 acetonitrile:water before switching to the organic solvent.
