Page 21 - BR20828_E Accucore 0713S

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Material Particle
Diameter Pore Diameter Bonded Phase Dimensions
Accucore 2.6 µm 80 Å RP-MS 100 × 2.1 mm
Accucore 2.6 µm 80 Å C18 100 × 2.1 mm
Kinetex® 2.6 µm 100 Å C18 100 × 2.1 mm
Poroshell® 120 2.7 µm 120 Å SB-C18 100 × 2.1 mm
Ascentis® Express 2.7 µm 90 Å C18 100 × 2.1 mm
Halo® 2.7 µm 90 Å C18 100 × 2.1 mm
Nucleoshell® 2.7 µm 90 Å RP C18 100 × 2.0 mm
SunShell ® 2.6 µm 90 Å C18 100 × 2.1 mm
Table 4: Columns tested
Characterization tests
Experimental Conditions Hydrophobic
Test Low pH Test Neutral pH Test
Mobile phase 65:35 (v/v)
methanol /water
45:55 (v/v) methanol/
10 mM phosphate
buffer pH 2.7
80:20 (v/v) methanol/
10 mM phosphate
buffer pH 7.6
Flow rate (mL/min) 0.55 0.55 0.55
Column temperature (°C) 40 40 40
Detection UV at 254 nm UV at 254 nm UV at 254 nm
Injection volume (μL) 1 1 1
Table 5: Experimental conditions
Selectivity comparison
Figures 1 to 3 give examples of the chromatograms from
the three tests on the Accucore RP-MS column,
demonstrating typical elution order for the test probes in
each test. Figure 4 provides an overview of the relative
hydrophobic retention (HR) and steric selectivity (SS) of
all the phases compared in this document. Accucore
RP-MS, Poroshell 120 SB-C18, and Kinetex C18 phases
all exhibit similar HR. HR is significantly higher on
SunShell C18, Nucleoshell RP-C18, and Halo C18 phases.
The latter exhibits the highest hydrophobic retention of
all the phases tested. The phase that exhibits the highest
steric selectivity is Accucore C18 (SS 1.4). Accucore
RP-MS, Poroshell 120 SB-C18, and Kinetex C18 phases
all exhibit similar steric selectivity (SS around 1.1); for the
other four phases, SS varies between 1.17 and 1.30.
Therefore, out of all the phases tested, Accucore C18
provides the best balance between hydrophobic retention,
and thus retention time, and steric selectivity, which is a
measure of the ability of the phase to separate compounds
with similar structures.
From Figure 5, we can observe that the hydrophobic
selectivity (HS) is comparable for all the materials. The
hydrogen bonding capacity (HBC) is very low for all the
materials assessed in this study, providing evidence that all
the phases are effectively endcapped.
The activity towards bases (BA, tailing factor of
amitriptyline) is comparable for most materials (average
of 1.3), but slightly higher for SunShell C18 (1.6), which
is evidence of the presence of dissociated silanols, which
interact with protonated bases. The activity towards
chelators (C) is relatively low, reflected by an average
tailing factor for quinizarin of 1.5; however, the quinizarin
tailing factor values for Poroshell 120 SB-C18 and
SunShell C18 phases are 2.0 and 1.9, respectively, which
demonstrate higher metal contents on the silica supports
in these phases. The ion exchange capacity at pH 7.6 is
very low for Accucore C18 and RP-MS, Halo C18,
Ascentis Express C18, and SunShell C18 columns (IEX
7.6 of 1.0) but high for Poroshell 120 SB-C18 (IEX 7.6 of
1.6), highlighting a higher silanolic activity on the surface
of the silica. In contrast, there is no evidence of dissociated
acidic silanols on any of the phases tested, since the values
of IEX 2.7 are very low for all phases. The activity
towards acids (AI, tailing factor for chlorocinnamic acid)
is similarly low for all the columns (average value 1.2),
with the exception of SunShell, which has a value of 1.5.