Frictional Heating - Agilent Technologies Agilent 1260 Infinity System User's Manual

Frictional Heating

Forcing mobile phase through the column at higher pressure and higher
flow rates generates heat. The resulting temperature gradients (radial and
longitudinal) can have an impact on the column efficiency.
where F is the flow rate and p is the pressure.
Powerful column thermostatting (for example, using a water bath)
generates a strong radial temperature gradient, which leads to significant
loss in column efficiency. Still- air column thermostatting reduces the
radial temperature gradient and therefore reduces the efficiency losses,
but a higher column outlet temperature has to be accepted. The raised
temperature may have an effect on selectivity. At lower back- pressure,
performance losses due to frictional heat are minimized so that 4.6 or
3 mm inner diameter sub- 2- micron columns still deliver superior
efficiencies compared with the respective 2.1 mm inner diameter columns.
In summary, the use of sub- two- micron packing material offers benefits of
increased efficiency, higher resolution and faster separations.
The features of the Agilent 1260 Infinity Binary LC are discussed in the
chapter Product Description. The chapter Optimization considers how to
apply the theory and use these features to develop optimized separations.
1260 Infinity Binary LC - System User Guide
2
Introduction
Frictional Heating
37