SELECTIONGUIDE
RestekCapillaryGCColumnSelectionGuide
Column Internal Diameter (ID)
Your need for
resolution
, the
concentrations of analytes
you anticipate in your samples, and
the
sample introduction and analyte detection
instrumentation you are usingwill influence
your choice of column internal diameter.
When all other column parameters and analysis conditions are held constant, analyte retention
increases, and resolution improves, as column internal diameter is decreased. Sample capacity
increases as internal diameter is increased. Bleed also increases as column diameter is increased
and film thickness is held constant, because there ismore stationary phase in the column,
however for most applications the difference in bleedwill be insignificant.
Columns with an ID of 0.25mm or less offer the highest column efficiencies, and therefore the
greatest resolution, but have limited sample capacities, relative towider ID columns. If
concentrations of analytes in your samples exceed the capacity of the column, the analysis will
be characterized by peak distortion, poor resolution, and poor reproducibility. For many
applications a 0.32mm ID column offers the best balance of resolution and sample capacity.
0.53mm ID columns are best for high flow situations, such as accommodating incoming samples
