HILIC PHASES (Part 2 of 2)
The beneficial concept of HILIC phases
The advantage of HILIC phases is the use of water and volatile buffers. The aqueous systems allow a high solubility of polar compounds and a compatibility with ESI-MS detectors.
The betaine structure of zwitterionic HILIC phases, such as the newly developed NUCLEODUR®HILIC, facilitates a good selectivity by weak ionic interaction and requires low concentrations of MS-compatible buffers.
Zwitterionic structure of NUCLEODUR® HILIC
NUCLEODUR® HILIC is a zwitterionic phase with nearly complete charge equalization, ensured by a special patent pending procedure of bonding 3-N,N-dimethylaminopropanesulfonic acid to silica gel. A rapid equilibration characterizes the phase.
Equilibration and relative lifetime of NUCLEODUR® HILIC
Neutral HILIC phases show weak or no ionic interaction. Thus they are less selective. Though charged phases have a higher selectivity by ionic interaction, they require a higher concentration of buffers. This can cause problems with detection.
Fields of application of HILIC phases
Medium-polar and polar substances can be found more and more in all fields of HPLC.
Thus not only determinations of polar compounds in food, such as currently melamine in milk or acrylamide in bakery products are necessary, but also separations of vitamins and organic acids in foodstuff and pharmaceutical products. All these separations are efficiently performed on HILIC columns.
Stable and effective application notes were developed on NUCLEODUR® HILIC also for pharmaceutical and physiological substances, like the chemotherapeutic agent 5-fluorouracil, the energy carrier of muscle metabolism creatine, of catecholamines and amino acids.
In bioanalysis nucleotides, as well as pyrimidine and purine bases can be determinated efficiently.
Because well-biodegradable, but more and more polar pesticides have to be analyzed, the determination of chlormequat, mepiquat, paraquat and diquat gains increasing importance.
Determinations of hydrocarbons, peptides and glycolised or phosphorylised compounds are other successful applications of HILIC phases.
Advantages of NUCLEODUR® HILIC
- NUCLEODUR® HILIC is outstandingly suited for the chromatography of medium-polar, polar and ionic compounds.
- It stands out due to short equilibration time and good lifetime.
- Besides the established detection systems UV and fluorescence an application with highly sensitive LC-MS, LC-MS/MS and light scattering detectors is possible.
- It is the alternative to RP-18 and further RP phases, to NP and ion exchanger phases for a reliable analysis.
MACHEREY-NAGEL offers a new special HPLC phase for separation of polar compounds. The new NUCLEODUR® HILIC consisting of specially ammonium sulphonic acid modified silica offers innovative ways to separate highly polar and hydrophilic analytes under reversed phase conditions.
Based on ultra-pure NUCLEODUR® silica this modern HPLC phase is distinguished by its high reproducibility, stable chromatography and short equilibration times. So it´s perfectly suitable for analysis of polar organic acids and bases, natural compounds, amino acids or polar pesticides.