Introduction
There are so many different C18 columns to choose from,
that finding the right column for a particular separation
can be very time consuming and expensive. Two apparently
similar C18 phases can give very different results. For
example, Figure 1 compares the separation of the same
sample mixture on a Hypersil HyPurity C18 and a
Symmetry C18 column under identical mobile phase
conditions. Even though both columns are packed with base
deactivated C18 stationary phases, the band spacing
(selectivity) between peaks is very different on the two
columns. Without more information, it is impossible to
predict how the performance of different stationary phases
will compare.
This Comparison Guide to C18 Reversed Phase HPLC
Columns provides basic comparison information on
commonly used C18 columns to help you more easily
identify similarities and differences before investing time
and money in chromatographic testing. Hopefully, this information
will help you find the right column for your
application quicker.
Only silica based C18 bonded phases are evaluated in this
Guide. Other bonded phases, such as C8, CN, Phenyl and
polar embedded phases, are excluded.
This Guide does not identify an overall “best” column. The
column that works best for one application will not
necessarily be the column that will work best for other
applications. And, there certainly is not a single column that
will work best for all applications. However, this Guide can
help you identify columns that are likely to perform well
so that at least you can narrow the number of columns for
chromatographic testing. You may find that this Guide helps
you identify several columns that provide good separations
and performance. It is always desirable to have more than
one column identified for an application, especially if you are
running routine assays.
Increasingly, chromatographers are seeking to identify
alternate brands of HPLC columns suitable for their assays.
Having an alternate column choice for a method reduces
the risk of “down time” due to column problems such as a
change in selectivity from one manufactured lot to another
or slow supplier delivery. Finding an alternate or back-up
column that will provide acceptable selectivity and
performance when substituted into a method can be as
expensive and time consuming as finding the right column
for developing an initial separation. It is our hope that this
Guide will make that job easier by identifying columns with
similar chromatographic characteristics.