- The seal wash system must never run dry, particularly during separations that use a polar mobile phase.
- Isopropyl alcohol or mixtures of methanol and water, like 20% methanol/water, are effective seal wash solvents for THF solvent mixtures.
- For reversed-phase applications, use aqueous seal wash solutions with a weak organic component (for example, 1:9 methanol/water).
- Do not use 100% organic seal wash solutions.
Wash Solvent (needle wash):
- Avoid buffered wash solvents.
- The wash solvent must be strong enough to dissolve any remaining sample, and the wash duration must be long enough to remove residue from the system.
- HFIP should never be used in wash solvents.
- Do not use concentrations of THF or hexane greater than 10% as purge solvent.
- Typical organic sample diluents such as dimethylsolfoxide (DMSO) and dimethylformamide (DMF) are supported.
- Waters recommends a purge solvent of 90/10 water/methanol whenever possible.
- Do not leave buffers stored in the system.
- Flush all flow paths, including the needle wash, with plenty of non-buffered solvent before shutting down the system.
- For extended shutdown periods (longer than 24 hours), use 10% to 20% methanol in water.
- When using a buffered wash solvent, prime it for a minimum of 30 seconds.
- Use of buffers can cause salt buildup on the needle and wash port, which can require periodic cleaning.