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Obelisc improve productivity in HPLC


Obelisc™ HPLC columns are the latest, innovative columns from SIELC Technologies. Obelisc improve productivity in HPLC using only two column, Use Obelisc R and Obelisc N for chromatography of full range of small molecules. The technical basis of Obelisc is the Living Separation Cell Technology. Many patents protect this technology.

The Technology simulates living cells

Liquid Separation Cell Structure

  • A living cell has stationary (bound) and exchangeable (mobile) components
  • The internal environment is quite different from the external environment (mobile phase)
  • pH and ionic strength inside the cell differ from outside the cell
  • Pore opening acts as a membrane channel for the analytes
  • The cell responds to changes in external environment with physical and chemical changes
  • These changes include conformational changes in the long hydrophobic and hydrophilic chains, degree of ionization, charge distribution and counter-ion properties


Obelisc improve productivity in HPLC using only two column

Obelisc R with reversed-phase characteristics, Obelisc N with normal-phase characteristics,
separate polar and non-polar compounds using multiple separation mechanisms.

Properties of the two Obelisc HPLC column with liquid Separation Cell Properties

Chromatographers are trained to employ multiple HPLC columns such as reversed-phase (RP), AQ-type reversed-phase, polar-embedded group RP columns, normal-phase, cation-exchange, anion- exchange, ion-exclusion, and HILIC (Hydrophilic Interaction Liquid Chromatography) columns. Obelisc multimode column unite different functionality in two column.  The resultants is a cost effective dual system.
Using only two Obelisc columns Method development is easy. Compatible mobile phases enable mass spec or low UV (<220 nm). Obelisc R and Obelisc N differ in the type and proximity of their charged groups and the hydrophobicity of their long chains.

Obelisc R has cationic groups close to the silica surface separated from anionic groups by a hydrophobic chain.

Types of Interaction of Obelisc R

  • Obelisc R is a reverse-phase analytical column that  can be used in traditional, reversed-phase type applications.
  • Due to the presence of ionic groups and a long hydrophobic chain, Obelisc R offers additional retention and tuning that is not available with traditional reversed-phase columns.
  • Multiple separation modes (RP, NP, IE).
  • Mass spec, ELSD, preparative and low UV (<220 nm) compatible, low concentration buffers.

For Obelis R methods visit our compound specific Method Library

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Obelisc N has anions close to the surface separated from cationic groups by a hydrophilic chain.

Types of interaction of Obelisc N

  • Obelisc N is a column with very polar characteristics that works well for polar and charged analytes.
  • Offers both positively and negatively charged groups to interact with positively or negatively charged analytes.
  • Multiple separation modes (NP, HILIC, IE).
  • In HILIC mode, Obelisc N offers different selectivity form other HILIC or bare silica columns.
  • Mass spec, ELSD, preparative and low UV (<220 nm) compatible, low concentration buffers.

For Obelis N methods visit our compound specific Method Library

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Obelisc R and Obelisc N Columns – A Powerful Duo for HPLC

• Two columns able to keep and separate all types of small molecules and their mixtures
• Fast method development with only two columns
• Simple mobile phase choice
• Multiple separation modes (RP, NP, HILIC, IE)
• Mass spec, ELSD, preparative and low UV (<220 nm) compatible, low concentration buffers.
• Adjustable selectivity in all modes based on organic content, pH, and buffer strength

Indeed, applying Obelisc liquid separation cells to chromatographic separations supplies quite different results from all other chromatographic columns. Charge and chain conformation are tuneable properties that allow dramatic changes in separation selectivity. Method development now returns to an experimental science rather than trial-and-error screening of columns.

Chromatogram below shows the separation of a mixture with similar mobile phases on Obelisc R and N. Peak order is reversed just by changing acetonitrile content in the mobile phase. The hydrophobic propyl paraben retains much longer on Obelisc R due to the column’s reversed-phase characteristics. The polar compounds, dopamine and DOPA, retain much longer in normal-phase mode on Obelisc N.

Chromatogram Obelisc R and N HPLC


Loading capacity of Obelisc R column

Obelisc columns have high density of positive and negative ions on a stationary-phase surface. This property is favourable for using Obelisc column for preparative chromatography. The Obelisc columns offer significantly higher loading capacity (more than 10 times) with charged compounds compared to traditional RP columns. Neutral molecule can be preparatively separated on Obelisc like other RP columns.

Having two opposite charges allows to retain polar compounds on Obelisc columns without using ion-pairing reagents.
Obelisc technology allows to use much higher organic concentration than traditional RP columns while separating polar compounds.

Loading capacity Obelisc R compared to others