Agilent Technologies Agilent 1260 Infinity System User's Manual page 30

2
Introduction
Theory of Using Smaller Particles in Liquid Chromatography
The van Deemter plots in
size 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 7
30
Figure 7
Van Deemter curve for different particle sizes
on page 30 show that reducing particle
1260 Infinity Binary LC - System User Guide