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How to Achieve Higher Resolution
Increased resolution in a separation will improve the qualitative and
quantitative data analysis, allow more peaks to be separated or offer
further scope for speeding up the separation. This section explains how
resolution can be increased by examining the following points:
• Optimize selectivity
• Smaller particle- size packing
• Longer columns
• Shallower gradients, faster flow
• Minimal extra- column volume
• Optimize injection solvent and volume
• Fast enough data collection
Resolution between two peaks is described by the resolution equation:
where
• R
• N=plate count (measure of column efficiency),
• α=selectivity (between two peaks),
• k
The term with the most significant effect on resolution is the selectivity, α,
and practically varying this term involves changing the type of stationary
phase (C18, C8, phenyl, nitrile etc.), the mobile phase and temperature to
maximize the selectivity differences between the solutes to be separated. This
is a substantial piece of work which is best done with an automated method
development system which allows a wide range of conditions on different
columns and mobile phases to be assessed in an ordered scouting protocol.
This section considers how to get higher resolution with any chosen
stationary and mobile phases. If an automated method development system
1260 Infinity Binary LC - System User Guide
=resolution,
s
=retention factor of second peak (formerly called capacity factor).
2
Optimization of the Agilent 1260 Infinity Binary LC
How to Achieve Higher Resolution
3
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