Page 9 - Analityka 1/2015

Retention mechanism NAUKA
in high performance liquid
chromatography

PART I – NORMAL PHASE LIQUID CHROMATOGRAPHY
High performance liquid chromatography is a universal method that allows to determine
different types of substances. This technique is available in three chromatographic sys-
tems: in a normal- (NP) and reversed-phase (RP) and hydrophilic interaction liquid chro-
matography (HILIC). Each of these systems is characterized by different propeprties and
separation mechanis. High performance liquid chromatography in the normal phase, as
a technique that applies a more polar stationary phase than the mobile phase allows for
the analysis of weakly polar and polar compounds that exhibit retention in corresponding
chromatographic system. The most common stationary phases in NP system are unmodi-
fied silica gel and a chemically modified silica containing: cyano, amino, hydroxyl and
amide groups. The mobile phase is a non-aqueous organic solvent or a mixture of solvent.
The retention mechanism in the normal phase is carried out on the basis of preferential
adsorption of analyte molecules on the surface of a polar stationary phase. High
performance liquid chromatography in the normal phase chromatography system
is the oldest. It is displaced by modern variants of this technique.

ANALITYKA – NUMER 1, ROK (XVI) 2015 13