Use seal wash liquid that fulfills the following requirements:
The seal wash liquid is miscible with the solvent that is used in the pump.
The seal wash liquid is compatible with the seal wash tubing.
The seal wash liquid provides certain conductivity for reliable performance of the seal wash detector.
HPLC-grade water with 10% methanol is an appropriate choice.
With a Vanquish Core system that has been modified for NP applications, the appropriate liquid depends on the application:
NP application:
Use ammonium formate in isopropanol (2 mmol/L).
RP application:
Use HPLC-grade water with 10% methanol.