Orthogonality; Resolution - Agilent Technologies 1290 Infinity II 2D-LC Solution User Manual

15 Theoretical Background
Theoretical basis of 2D-LC

Orthogonality

The 2D-LC separation power depends the fact that the two selectivity
mechanisms in the different separation stages must be as different as possible.
If the mechanisms are completely different and independent the two separations
are called orthogonal.
Any correlation between the selectivity mechanisms degrades orthogonality and
reduces the efficiency of the 2D-LC system.
For strategies to achieve maximum orthogonality, refer to
and

Resolution

A chromatographic separation can be optimized based on physical parameters
of the HPLC column such as particle size, pore size, morphology of the particles,
the length and diameter of the column, the solvent velocity, and the temperature.
In addition, the thermodynamics of a separation can be considered and the
properties of the solute and the stationary and mobile phases (percentage of
organic solvent, ion strength, and pH) can be manipulated to achieve the shortest
possible retention and highest selectivity.
1D-LC Resolution (R
•
•
•
Figure 120 Resolution equation
This means that the selection of appropriate mobile and stationary phase
properties and temperature is critical in achieving a successful separation.
2D-LC - User Guide
Table 28 on page 338.
) can be described as a function of three parameters:
S
Column efficiency or theoretical plates (N),
Selectivity (α),
Retention factor (k).
Table 27 on page 333
325