Reversed-phase high-performance
liquid chromatography (RP-HPLC)
is the most popular chromatographic mode, accounting for more than
90% of all separations. HPLC itself owes its immense popularity to
it being relatively simple and inexpensive, with the equipment being
reliable and easy to operate. Due to extensive automation, it can
be run virtually unattended with multiple samples at various separation
conditions, even by relatively low-skilled personnel. Currently, there
are >600 RP-HPLC columns available to end users for purchase, some
of which exhibit very large differences in selectivity and production
quality. Often, two similar RP-HPLC columns are not equally suitable
for the requisite separation, and to date, there is no universal RP-HPLC
column covering a variety of analytes. This forces analytical laboratories
to keep a multitude of diverse columns. Therefore, column selection
is a crucial segment of RP-HPLC method development, especially since
sample complexity is constantly increasing. Rationally choosing an
appropriate column is complicated. In addition to the differences
in the primary intermolecular interactions with analytes of the dispersive
(London) type, individual columns can also exhibit a unique character
owing to specific polar, hydrogen bond, and electron pair donor–acceptor
interactions. They can also vary depending on the type of packing,
amount and type of residual silanols, “end-capping”,
bonding density of ligands, and pore size, among others. Consequently,
the chromatographic performance of RP-HPLC systems is often considerably
altered depending on the selected column. Although a wide spectrum
of knowledge is available on this important subject, there is still
a lack of a comprehensive review for an objective comparison and/or
selection of chromatographic columns. We aim for this review to be
a comprehensive, authoritative, critical, and easily readable monograph
of the most relevant publications regarding column selection and characterization
in RP-HPLC covering the past four decades. Future perspectives, which
involve the integration of state-of-the-art molecular simulations
(molecular dynamics or Monte Carlo) with minimal experiments, aimed
at nearly “experiment-free” column selection methodology,
are proposed.
