24
Drain tube
Syringe
Syringe needle with fitting
Syringe
needle
Removed drain tube
Drain port
(a)
(b)
Figure 4.2 Removing Air Bubbles via Syringe
4.2 Pump solvent replacement
This section explains how to quickly replace the solvent in the pump. The
procedures described in this section can also be used to replace the solvent in the
equipment upstream from the pump (for example, a degasser, 6 solvent selection
valve or low pressure gradient unit). However, this method introduces air bubbles
and therefore should not be used to replace the solvent in the column or detector
(cell).
In the example described below, a pump (including the inlet tube) contains a buffer
solution containing salts (referred to below as buffer) that is to be replaced with
methanol. Water will be used as an intermediate solvent in the process of replacing
the buffer with methanol.
4.2.1 Solvent replacement preparations
(1) Connect a 0.25 mm i.d. stainless steel tube to the pump outlet port.
Note: The use of tubes having an inside diameter of 0.5 mm or greater makes it
difficult to determine whether or not the solvent has been completely drained.
(2) Set the flow rate to 10 ml/min and the maximum pressure to 3.0 MPa.