Operational Hints For The Multi Channel Gradient Valve (Mcgv) - Agilent Technologies InfinityLab LC Series User Manual

4 Optimizing Performance

Operational Hints for the Multi Channel Gradient Valve (MCGV)

Operational Hints for the Multi Channel Gradient
Valve (MCGV)
In a mixture of salt solutions and organic solvent the salt solution might be well
dissolved in the organic solvent without showing precipitations. However in the
mixing point of the gradient valve, at the boundary between the two solvents,
micro precipitation is possible. Gravity forces the salt particles to fall down.
Normally the A channel of the valve is used for the aqueous/salt solution and the
B channel of the pump is used for the organic solvent. If used in this
configuration the salt will fall back into the aqueous solution and will be
dissolved. When using the pump in a different configuration (e.g., D - salt solution,
A - organic solvent) the salt can fall into the port of the organic solvent and may
lead to performance problems.
When using salt solutions and organic solvents it is recommended to connect
NOTE
the salt solution to one of the bottom ports of the MCGV and the organic solvent
to one of the upper gradient valve ports. It is best to have the organic channel
directly above the salt solution channel. Regular flushing with water of all MCGV
channels is recommended to remove all possible salt deposits in the valve ports.
Precipitations formed during the mixing of buffers and organic solvents which do
NOTE
not dissolve salts may cause a loss of pump performance (flow/retention time
stability), a blockage or internal leak of the pump. Avoid the use of such solvent
combinations, as they can cause irreproducible chromatographic results.
The use of an Inline filter (G1311-60006) can avoid or reduce such effects by
filtering crystals and re-dissolving them over time.
Agilent InfinityLab LC Series 1260 Infinity II Isocratic and Quaternary Pumps User Manual 81