ZIC®-cHILIC HPLC and LC-MS Columns
SeQuant® ZIC®-cHILIC HPLC columns provide complementary selectivity to optimize separations of polar hydrophilic compounds. The columns carry a novel densely bonded, 1:1 charge-balanced phosphorylcholine functional group. As with all true zwitterionic stationary phases, straightforward and reproducible separations are achieved by hydrophilic partitioning combined with weak ionic interactions.
The more accessible positive charges of SeQuant® ZIC®-cHILIC columns enable selectivity tuning in chromatography through altered interaction with anionic and cationic molecular moieties. This can be favorable in several situations, for example in the separation of labile metal complexes or highly polar and multiply charged aminoglycosides. Their extraordinary stability and minimized bleed also make SeQuant® ZIC®-cHILIC columns the preferred choice for many LC-MS applications.
Alternative choices for the separation of polar hydrophilic compounds include silica-based SeQuant® ZIC®-HILIC columns with identical functional groups, and polymer-based SeQuant® ZIC®-pHILIC columns with excellent pH stability.
German scientists compared the selectivity of SeQuant® ZIC®-HILIC and SeQuant® ZIC®-cHILIC columns for the separation of metal complexes. Labile complexes between positively charged metals and their ligands were more stable when separated on ZIC®-cHILIC, demonstrating its complementary selectivity compared to ZIC®-HILIC, and the benefit of weak electrostatic interactions.
“…it seems that the ZIC®-cHILIC material is better suited for the separation of more labile metal species…”
Weber et al., J. Sep. Sci. 31 (2008) 1615-1622
Isocratic separation of positively charged benzyltrimethylamine (BTMA, peaks indicated with arrows), neutral toluene (void marker), uracil and cytosine on ZIC®-cHILIC (left) and ZIC®-HILIC (right) illustrates the similarities and differences in selectivity caused by the different orientation of the zwitterionic functional groups. Column dimensions were 100 x 4.6 mm, eluent was 80:20 acetonitrile / 25 mM aqueous ammonium acetate pH 6.8, pumped at 0.5 mL/min at 23 °C, and detection was accomplished by UV absorption at 254 nm.
Aminoglycoside antibiotics contain amino-modified sugar moieties, thus they are very hydrophilic and multiply positively charged at neutral and acidic pH. This makes them very difficult to separate using reversed-phase columns and most HILIC HPLC columns. In contrast, thanks to their complementary selectivity, SeQuant® ZIC®-cHILIC columns are ideal for the analysis of aminoglycoside antibiotics.
SeQuant® ZIC®-cHILIC columns provide impressive separations of nucleotides with excellent peak shapes. The stationary phase offers advantageous weak ionic interactions for enhanced selectivity, but not excessive retention or serious peak shape distortion, which can be observed on other HILIC columns.
|Charge arrangement and functional group||Features||Base particle||Particle size||Pore size||Column types|
|New complementary selectivity with favorable LC-MS performance||silica||3 µm||100 Å||analytical,