1.2.2 APH operation
The standard APH assembly provides thermal equilibration by heating the incoming mobile phase
and sample to the specified column temperature before it enters the column. The assembly uses
an electric heating element to directly heat the column-inlet tubing. The rapid heating, low-volume
design reduces gradient delay and extra-column band-spreading. It ensures that high-flow rate
separations occur at the desired column temperature, not at the ambient temperature of the
incoming solvent. By actively controlling the temperature of the mobile phase at the point of use—
the column inlet—sensitivity to ambient temperature swings is greatly reduced. When preheating
is unnecessary, you can disable the APH functionality via the console or the method editor in the
chromatography data software.
Figure 1–4: Typical APH assembly
#1 knurled compression fitting with back-locking PEEK ferrule
#2 locking cap nut
APH circuit board
APH-inlet tubing
SST sleeve
Long, flat compression screw fitting for connecting to valve assembly
Protective cap covering tubing and ferrule
1.2.3 Column stabilizer operation
The column heater’s optional column-stabilizer assembly reduces sensitivity to ambient
temperature swings by transferring heat (via conduction) from the column heater’s heating
element through the thermal gasket to the column-inlet tubing. The looped tubing path reduces
dispersion while ensuring maximum surface area contact between the tubing and the column tray,
maximizing heat transfer to the mobile phase.
The column stabilizer provides thermal equilibration by heating the incoming mobile phase and
injected sample to the specified column temperature before they enter the column.
December 4, 2019, 715005052 Version 02 (previously released as Rev.B)
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