ZORBAX 80Å Extend-C18

Agilent ZORBAX 80Å Extend-C18

High efficiency and long lifetime at elevated pH—stable up to pH 11.5 for demanding basic methods.
Bidentate C18 bonding and double endcapping provide exceptional high-pH durability and minimize silica dissolution.
Better peak shape and higher efficiency than traditional polymer-based columns under alkaline conditions.
Excellent LC/MS sensitivity for peptides, small molecules, and other analytes requiring high-pH elution.

The Agilent ZORBAX Extend-C18 series is engineered for laboratories requiring reliable performance under harsh alkaline conditions. Traditional silica-based columns rapidly degrade at pH > 8, but Extend-C18 columns use a proprietary bidentate organosilane bonding architecture that anchors C18 chains to the silica surface at two points. This unique structure—combined with double endcapping—shields the silica backbone from high-pH hydrolysis, enabling stable, long-term operation up to pH 11.5.

Extend-C18 columns deliver more efficiency, sharper peaks, and improved reproducibility compared to polymer-based alternatives, especially for compounds that benefit from alkaline mobile phases. Their performance makes them an excellent choice for peptide mapping, small-molecule basic analytes, method development, and LC/MS workflows requiring enhanced selectivity at elevated pH.

For additional options or guidance on Chrom Tech’s full liquid chromatography column portfolio, please contact us or reach out to our technical support specialists.

Key Definitions ▸

Bidentate Bonding

A dual-anchor bonding strategy in which the C18 ligand is attached at two points to the silica surface. This reinforcement dramatically improves stability at high pH (up to 11.5), preventing ligand loss and maintaining long-term column performance.

Double Endcapping

A secondary surface treatment that removes residual silanols, improving peak shape and reducing tailing—especially important for peptides, basic compounds, and high-pH separations.

High-pH Liquid Chromatography

A separation mode requiring stable bonded phases capable of resisting silica dissolution above pH 8. Extend-C18 supports operation up to pH 11.5, enabling improved retention and selectivity for peptides and other basic analytes.

Type B Silica

High-purity silica with low metal content, delivering better peak shapes and enhanced reproducibility. Essential for sensitive LC/MS peptide work and high-pH mobile phases.

LC/MS Peptide Analysis

A workflow that benefits from extended retention, sharp peak shape, and high sensitivity. Extend-C18’s high-pH stability enhances ionization efficiency and improves detection of peptides and small biomolecules.

Frequently Asked Questions ▸

What makes ZORBAX Extend-C18 suitable for high-pH separations?

Extend-C18 columns feature Agilent’s proprietary bidentate C18 bonding and double endcapping, providing exceptional resistance to silica dissolution. This allows reliable operation at pH values up to 11.5—ideal for basic compounds and high-pH method development.

Can Extend-C18 replace polymer-based columns for basic analytes?

Yes. Extend-C18 columns provide better efficiency, improved peak shape, and reduced bleed compared to polymeric phases—while still delivering the high-pH stability needed for strong bases.

Is Extend-C18 recommended for peptide LC/MS?

Absolutely. Its unique bonding chemistry improves retention, selectivity, and sensitivity for peptides under LC/MS conditions, making Extend-C18 a preferred high-performance option for peptide workflows.

Product List

SKU	Name	LC Column Phase	Particle Size	Inner Diameter (ID)	Length
SKU 764953-902	Name 764953-902 - Zorbax Extend C18, 3.5um, 4.6 x 100mm	LC Column Phase Extend-C18	Particle Size 3.5 um	Inner Diameter (ID) 4.6 mm	Length 100 mm
SKU 764953-302	Name 764953-302 - Extend-C18 3.0 x 100mm 3.5u	LC Column Phase Extend-C18	Particle Size 3.5 um	Inner Diameter (ID) 3 mm	Length 100 mm
SKU 735953-902	Name 735953-902 - Extend-C18 3.5u 4.6x50mm	LC Column Phase Extend-C18	Particle Size 3.5 um	Inner Diameter (ID) 4.6 mm	Length 50 mm
SKU 759700-902	Name 759700-902 - RRHD Extend-C18,2.1x150mm,1.8um,1200bar	LC Column Phase Extend-C18	Particle Size 1.8 um	Inner Diameter (ID) 2.1 mm	Length 150 mm
SKU 735700-902	Name 735700-902 - Extend-C18 Rapid Res. 3.5u 2.1x50mm	LC Column Phase Extend-C18	Particle Size 3.5 um	Inner Diameter (ID) 2.1 mm	Length 50 mm
SKU 759700-302	Name 759700-302 - RRHD Extend-C18,3.0x150mm,1.8um,1200bar	LC Column Phase Extend-C18	Particle Size 1.8 um	Inner Diameter (ID) 3 mm	Length 150 mm
SKU 758700-902	Name 758700-902 - RRHD Extend-C18,2.1x100mm,1.8um,1200bar	LC Column Phase Extend-C18	Particle Size 1.8 um	Inner Diameter (ID) 2.1 mm	Length 100 mm
SKU 758700-302	Name 758700-302 - RRHD Extend-C18,3.0x100mm,1.8um,1200bar	LC Column Phase Extend-C18	Particle Size 1.8 um	Inner Diameter (ID) 3 mm	Length 100 mm
SKU 728975-902	Name 728975-902 - Extend-C18,4.6 x 100mm,1.8um,600bar	LC Column Phase Extend-C18	Particle Size 1.8 um	Inner Diameter (ID) 4.6 mm	Length 100 mm
SKU 728975-302	Name 728975-302 - Extend-C18, 3.0x100mm, 1.8um, 600bar	LC Column Phase Extend-C18	Particle Size 1.8 um	Inner Diameter (ID) 3 mm	Length 100 mm
SKU 746450-902	Name 746450-902 - Extend-C18 analytical, 5um, 4.6x50mm	LC Column Phase Extend-C18	Particle Size 5 um	Inner Diameter (ID) 4.6 mm	Length 50 mm
SKU 728700-902	Name 728700-902 - Extend-C18 2.1 x 100 mm	LC Column Phase Extend-C18	Particle Size 1.8 um	Inner Diameter (ID) 2.1 mm	Length 100 mm

Shop All HPLC Columns →