Agilent Technologies Agilent 1260 Infinity System User's Manual page 29

The Theory
Separation efficiency in HPLC can be described by the van Deemter
equation
that is used to measure the dispersion of analytes as they move down the
column. H is the Height Equivalent to a Theoretical Plate (sometimes
HETP), d
linear velocity of the mobile phase and A, B and C are constants that are
related to the different dispersive forces. The A term relates to eddy
diffusion or multiple flow paths through the column; B relates to
molecular diffusion along the column axis (longitudinal); C relates to mass
transfer of the analyte between the mobile and stationary phases. The
separation is at its most efficient when H is at a minimum. The effect of
each individual term and the combined equation are shown in
page 29where the plate height is plotted against the linear flow rate
through the column. This type of plot is known as a Van Deemter Curve
and is used to determine the optimum flow rate (minimum point of the
curve) for best efficiency of separation for a column.
Figure 6
1260 Infinity Binary LC - System User Guide
Theory of Using Smaller Particles in Liquid Chromatography
(Figure 6 on page 29). This results from the plate- height model
is the particle size of the column packing material, u
p
A hypothetical Van Deemter curve
2
Introduction
is the
0
Figure 6 on
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