Chromatographic Retention of Polar Compounds: What are the options?
Many lead compounds under research in the pharmaceutical
industry today are polar compounds that are difficult to retain on
standard reversed-phase columns. This makes HPLC method development
more demanding than it was in the past. What options are available to
retain very polar compounds, and what are their relative advantages and
disadvantages? In this presentation, we will discuss the different
techniques that are available for the retention of polar compounds.
These include reversed-phase techniques as well as techniques that can
be summarized as hydrophilic interaction chromatography (HILIC). Among
reversed-phase chromatography, we will discuss special phases that do
not exhibit hydrophobic collapse in water as eluent and phases with
embedded polar groups. Another option is the increase in retention that
is possible through pH changes, if the analytes are ionizable. Among
HILIC techniques, several options are available as well, ranging from
pure HILIC to the use of the ion-exchange properties of HILIC phases.
In all these comparisons, we are using mobile phases that are
compatible with high-sensitivity MS detection.