Agilent Technologies 1290 Infinity LC System System Manual And Quick Reference page 10

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Introduction to Ultra-High Performance Liquid Chromatography
Theory of Using Smaller Particles in Liquid Chromatography
The van Deemter plots in
increases efficiency. Switching from commonly used 3.5 µm and 5.0 µm
particle sizes to 1.8 µm particles offers significant performance improvements.
The 1.8 µm particles give two to three times lower plate height values and
proportionately higher efficiencies. This allows a shorter column to be used
without sacrificing resolution and hence the analysis time is also reduced by a
factor of two to three. The increased efficiency is derived to a large extent
from the reduction in multiple flow paths as a result of the smaller particles -
this leads to a smaller A term (eddy diffusion). In addition, smaller particles
mean shorter mass transfer times, reducing the C term, and it can be seen that
the overall effect is a much reduced loss of efficiency as the flow rate increases
(the slope of the line is reduced). This means that the separation on smaller
particles can be further accelerated by increasing the flow rates without
significantly reducing efficiency.
Figure 2
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Figure 2
Van Deemter curve for different particle sizes
Agilent 1290 Infinity LC System Manual and Quick Reference
on page 10 show that reducing particle size