Agilent Technologies Agilent 1260 Infinity System User's Manual page 33

2
Introduction
Theory of Using Smaller Particles in Liquid Chromatography
No matter whether the UHPLC separation method is being newly
developed or simply transferred from an existing conventional method, it
is clearly beneficial to have a wide choice of stationary phase chemistries
available in a range of column formats.
Agilent offers more than 140 ZORBAX 1.8 µm Rapid Resolution High
Throughput (RRHT) columns (14 selectivity choices; 15 to 150 mm long;
2.1, 3.0 and 4.6 mm internal diameters).
Additionally to the ZORBAX columns, PoroShell columns with nine
selectivity choices are available for use with the Agilent 1260 Infinity
Binary LC.
This enables the optimum stationary phase to be selected so that the
selectivity is maximized. The resolution, flow rate, and analysis time can
be optimized by selecting the appropriate column length and diameter and
operation with longer STM columns has become more accessible than ever
before.
PoroShell columns are so- called superficially porous particle (SPP)
columns. In contrast to totally porous silica columns, these SPP columns
have a solid core (1.7 µm in diameter) and a porous silica layer (0.5 µm
thickness) surrounding it. Speed and resolution of PoroShell columns are
comparable to sub- two micron columns with up to 50 % less backpressure.
PoroShell columns have enjoyed a recent resurgence in smaller particle
sizes than the older 'pellicular' particle columns. The current interest in
this technology is driven by its re- introduction in smaller particle sizes,
such as the sub 3 micron sizes, for use in typical small molecule reversed
phase separations.
Many laboratories perform an extensive screening process to select the
best combination of stationary phase, mobile phase, and temperature for
their separations. The Agilent 1200 Infinity Series Multi- Method
Development Solution facilitates complete automation of this
time- consuming selection process – making method development and
method transfer an easy and reliable task.
ZORBAX 1.8 µm RRHT columns use the same chemistry as ZORBAX
columns with 3.5 and 5 µm particles. As a result, for any particular
ZORBAX phase, the 5.0, 3.5 and 1.8 µm particles provide identical
selectivity, which allows easy, fast, and secure bidirectional method
transfer between conventional LC and UHPLC.
1260 Infinity Binary LC - System User Guide 33