Available now from Advanced Material Technologies are the new HALO® BioClass Oligo C18 HPLC columns.

Designed with proven Fused-Core® technology, the HALO® Oligo C18 provides the quality and reliability the HALO® brand is famous for. This column delivers excellent separation speed and highest chromatographic efficiency, optimised for the requirements of oligonucleotide separations.  

The new HALO® OLIGO C18 phase incorporates surface modified organo-silane technology for alkaline resistance, which results in excellent stability under elevated pH operating conditions common in oligonucleotide separation methods.  

The HALO® Oligo C18 is loaded into inert, surface passivated column hardware to reduce potential of sample adsorption which can occur with stainless steel hardware – ensuring the highest recoveries of analytes. The columns are ready for use with both standard or bio-inert instrumentation.

With a 120 Å pore size, the HALO® Oligo C18 delivers separations of oligomers up to 60 bases in length. The phase is designed for conditions suited for oligonucleotide separations, and displays excellent stability under high pH and high temperature environments, as well as being compatible with UHPLC and mass spectrometry analysis. Closely related impurities as well as recognition of failure sequences are easily achieved with the HALO® Oligo C18 columns.

HALO® Oligo C18 Specifications

  • Ligand: surface modified dimethyloctadecylsilane
  • USP Designation: L1
  • Particle Size: 2.7 µm
  • Pore Size: 120 Å
  • Low pH Limit: 2
  • High pH Limit*: 9
  • Temperature Limit at Low pH: 90°C
  • Temperature Limit at High pH*: 85°C
  • Endcapped: Yes
  • Carbon Load = 5.6%
  • Surface Area = 75 m2/g
  • Inert surface passivated column hardware

*Column lifetime will vary depending on the operating temperature and the type and concentration of buffers used – operation at extreme specifications of temperature and pH may reduce column lifetime. Consult the Column Care and Use document for more information.

For now, the HALO® Oligo C18 is available in limited dimensions – please contact us if you have a custom column request.

Performance You Can Rely On!

A less than 1% change in retention was achieved over 20,000 column volumes when testing the packaging material stability of the HALO® OLIGO C18 column. This stability run was performed at both high pH (10) and high temperature (60°C).

Rapid Separation of Oligonucleotide Ladder

The below example using the 2.1 x 50 mm HALO® OLIGO C18 column illustrates the resolution of an oligonucleotide standard mixture (10 – 60 mer ssDNA), using triethylammonium acetate (TEAA), with absorbance detection and gradient elution with acetonitrile. The fast separation is carried out in less than 3.5 minutes, and shows the excellent peak shape and high resolution of oligonucleotides of up to 60 oligonucleotides in length.

Excellent Lot-To-Lot Reproducibility

Four different lots of HALO® OLIGO C18 were tested using a ladder of single stranded DNA ranging in base length from 10 – 60 mer. The results show clear excellent lot-to-lot reproducibility of the column.

The HALO® Advantage

In the following study, the performance of the HALO® OLIGO C18 and a competitor oligonucleotide column were compared. An oligonucleotide ladder of mixed sequence and length was separated under high pH conditions.  The results show oligomers of 20 base length AND higher begin to tail significantly on the competitor column, whereas the same oligomers show no tailing on the HALO® column – displaying the chromatographic efficiency and speed of Fused-Core®. 

Note: Tailing of the competitor column could represent poor column loading, however, both the HALO® and competitor columns were QC tested and passed prior to analysis.

Surface Passivated HALO® Hardware

The surface passivated column hardware of the HALO® Oligo C18 columns creates an iron free bio-inert flow path, minimising unwanted interactions, in order to manage complex and reactive sample profiles.

Modern LC systems feature an array of exotic materials to achieve bio-inertness, however they are significantly more expensive than instruments constructed with stainless steel flow path components. 

This hardware shows improved peak shape and recovery compared to uncoated hardware.  In some cases, uncoated hardware needs to be conditioned before any signal is observed.  By using surface passivated HALO® hardware, there is no need for preconditioning the column before it is used.

Surface passivated HALO® hardware is recommended for phosphorylated compounds and analytes that would potentially chelate to metal surfaces. 

The HALO® surface passivated hardware will improve lifetime and consistency as well as deliver more performance and reliability compared to standard stainless steel hardware. 

Benefits of Surface Passivated Hardware Include: 

  • A bio-inert flow path 
  • Improves bio-inertness of frits that cannot be treated by other methods
  • Enhances chemical compatibility, even with harsh solvents such as THF that challenge PEEK materials
  • Increased durability – no cracking or flaking – twice the wear resistance of 304 stainless steel
  • Better corrosion resistance
  • More inert than glass

Conclusion

With excellent pH and temperature stability, the HALO® Oligo C18 columns are perfect for robust and reliable oligonucleotide separations. The inert surface passivated column hardware provides a bio-inert flow path to manage the complex and reactive sample profiles that are common in bioanalysis.