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.

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SKU Name LC Column Phase Particle Size Inner Diameter (ID) Length
SKU
820999-901
Name
820999-901 - High performance ZORBAX guard fittings kit
LC Column Phase
Particle Size
Inner Diameter (ID)
4.6 mm
Length
12.5 mm
SKU
820950-930
Name
820950-930 - Extend-C18, Guard, 5u, 4.6x12.5mm 4PK
LC Column Phase
Extend-C18
Particle Size
5 um
Inner Diameter (ID)
4.6 mm
Length
13 mm
SKU
820444-901
Name
820444-901 - PrepHT Guard Hardware Kit
LC Column Phase
Particle Size
Inner Diameter (ID)
Length
SKU
820400-901
Name
820400-901 - PrepHT,Hardware,21.2mm Crt.End Ftg 2/PK
LC Column Phase
Particle Size
Inner Diameter (ID)
21.2 mm
Length
SKU
821125-930
Name
821125-930 - Extend-C18, Guard, 5u, 2.1x12.5mm 4PK
LC Column Phase
Extend-C18
Particle Size
5 um
Inner Diameter (ID)
2.1 mm
Length
13 mm
SKU
820212-930
Name
820212-930 - PrepHT,Zorbax,Extend,Grd Crt,5um,2/PK
LC Column Phase
Extend-C18
Particle Size
5 um
Inner Diameter (ID)
16 mm
Length
8 mm
SKU
770450-902
Name
770450-902 - Extend-C18 Analytical, 5um, 4.6x250mm
LC Column Phase
Extend-C18
Particle Size
5 um
Inner Diameter (ID)
4.6 mm
Length
250 mm
SKU
773700-902
Name
773700-902 - Extend-C18, Narrow-Bore, 5u, 2.1x150mm
LC Column Phase
Extend-C18
Particle Size
5 um
Inner Diameter (ID)
2.1 mm
Length
150 mm
SKU
770450-302
Name
770450-302 - Extend-C18 3.0x250mm 5u
LC Column Phase
Extend-C18
Particle Size
5 um
Inner Diameter (ID)
3 mm
Length
250 mm
SKU
770150-902
Name
770150-902 - PrepHT,Zorbax,Extend,21.2x150mm,5uCrt
LC Column Phase
Extend-C18
Particle Size
5 um
Inner Diameter (ID)
21.2 mm
Length
150 mm
SKU
773450-902
Name
773450-902 - Extend-C18 Analytical, 5um, 4.6x150mm
LC Column Phase
Extend-C18
Particle Size
5 um
Inner Diameter (ID)
4.6 mm
Length
150 mm
SKU
763954-302
Name
763954-302 - Extend-C18, 3.0x150mm 3.5um
LC Column Phase
Extend-C18
Particle Size
3.5 um
Inner Diameter (ID)
3 mm
Length
150 mm