Normal Phase Applications - Agilent Technologies InfinityLab LC Series User Manual

3 Using the Module
Solvent Recommendation for Agilent 1290 Infinity and 1290 Infinity II and 1260
Infinity II Flexible Pumps

Normal Phase Applications

Valves for Normal Phase Applications (G7104A/C, G7120A)
Current passive inlet valves and outlet ball valves used with Agilent Infinity and
Infinity II pumps do not work well while running nonpolar solvents for normal
phase applications (for example, hexane and heptane). With such applications,
pressure drops could be observed. They are the result of particles in insulating
solvents, electrostatically charging up, and sticking to the nonconductive ruby
balls inside the standard valves, such that the valves no longer close properly
(could take just hours). For normal phase applications, a second type of valve is
available. These valves use a new material for valve balls, which is a conductive
ceramic. The ceramic balls do not charge up electrostatically and show good
performance in normal phase applications. The valves are marked with "N" to
stand for normal phase. Agilent recommends using these valves for (and only
for) normal phase applications.
To avoid changing to the Type N valves when running critical solvents, it is
possible to increase the conductivity of the mobile phase, by adding 5 % of a
miscible, polar solvent. In general, isopropanol is a good choice.
No design change has been done for active inlet valves, which have already been
used successfully for normal phase applications in 1260 Infinity I/II pumps.
Seals for Normal Phase Applications
For running normal phase applications on Agilent Infinity and Infinity II pumps,
yellow PE seals are required as piston seals. By default, 1290 Infinity, 1290
Infinity II, and 1260 Infinity II Flexible Pumps use ceramic pistons and yellow PE
seals as piston seals. 1260 Infinity I/II pumps use sapphire pistons and black
PTFE piston seals in a standard configuration. If using black PTFE seals with
normal phase applications, the black PTFE seals wear and generate small
particles. Such particles can clog valves and other parts in the flow path. When
running normal phase applications on 1260 Infinity I/II pumps, the piston seals
have to be changed to yellow PE seals. For optimum performance, PE seals
should be replaced during preventive maintenance.
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