compounds, whichwould elute prior to peak 1, the 5.0µm filmwould be required.
Both sample capacity and bleed increase as stationary phase film thickness is increased.
Changes in the column ID/stationary phase film thickness ratio, ß, are an important
considerationwhen youwant tomake a change in column internal diameter or in stationary
phase film thickness. Analyte retention increases as column internal diameter is decreased, and
analyte retention decreases as stationary phase film thickness is decreased. When other column
parameters and analysis conditions are held constant, a columnwith a smaller ß valuewill be
more retentive for a given analyte. To assure similar retention and resolutionwhen you increase
the column ID, you alsomust increase the stationary phase film thickness. Similarly, if youwish
to reduce the column ID, but keep retention and resolution similar, you alsomust reduce the
stationary phase film thickness.
lists ß values for common combinations of column ID
and stationary phase film thickness; where ß values for different combinations are similar,
elution patterns will be similar. To find ß values for other column ID/stationary phase film
combinations, use the
.
Figure 1
A sample containing low boiling components shows the differences in resolution among 0.25, 1.0, and 5.0µm columns. The 1.0µm column offers better resolution than
the 0.25µm column, and the 5.0µm column does not offer any further improvements for compounds eluting afterC6.
