Multiwash option is designed for the low carryover and can be installed in any Agilent Multisampler.
This option reduces carryover for critical samples by allowing:
External needle wash with up to three different solvents
Seat backflush with up to three different solvents
The use of the Multiwash option is not recommended with salt-containing mobile phases, as salt will crystallize on the needle and needle seat. Due to the flow path of the Multiwash hydraulic box, when the metering device moves to the home position before injection, the mobile phase will come out from the needle tip and might fall into the seat. This is expected behavior, independent of the Injection Path Cleaning settings, and does not indicate leakage.
If the Multiwash is installed on the system with salt-containing mobile phases, to avoid salt build-up on the needle and the seat, it is recommended to flush the Multisampler daily with water for 15 min and visually inspect the needle and seat. If necessary, use a lint-free tissue with distilled water to manually clean the needle, seat, and other parts that still contain salt residue.
When should the Multiwash option be used?
If the system is intended for reversed-phase applications only and no precipitating compounds are present in the mobile phase.
If the system is intended for applications with salt-containing mobile phases, the Multiwash option is not recommended. If the option is however installed, crystallization on the needle and the seat can take place. The following practices should be followed:
Perform daily a 15 min flushing with water to remove salt residue.
Perform external needle wash and seat backflush.
Visually control needle/seat/washport for salt residue.
Manually clean needle/seat/washport if necessary.
If the system is intended for alternating applications with salt-containing mobile phases AND reversed-phase applications, Multiwash option is not supported. There is a high risk that salt residue will be continuously released and either interfere with reversed-phase chromatography or even cause clogging of the system.
A considerable amount of solvent is aging in the lines of the Multiwash flow paths, which could lead to elevated background in highly sensitive UV and MS measurements. To mitigate this, it is recommended to prime solvents in each Multiwash line in use to the wash port and S1 line (initial chromatographic condition) to the seat for at least 5 minutes before actual LC analysis is started.
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id: 3803394827