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.

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SKU Name LC Column Phase Particle Size Inner Diameter (ID) Length
SKU
727975-902
Name
727975-902 - Extend-C18,4.6x50mm,1.8um,600 bar
LC Column Phase
Extend-C18
Particle Size
1.8 um
Inner Diameter (ID)
4.6 mm
Length
50 mm
SKU
727975-302
Name
727975-302 - Extend-C18 3.0 x 50 mm
LC Column Phase
Extend-C18
Particle Size
1.8 um
Inner Diameter (ID)
3 mm
Length
50 mm
SKU
727700-902
Name
727700-902 - Extend-C18, 2.1x50mm, 1.8um
LC Column Phase
Extend-C18
Particle Size
1.8 um
Inner Diameter (ID)
2.1 mm
Length
50 mm
SKU
726975-902
Name
726975-902 - Extend-C18,4.6x20mm,1.8um,600 bar
LC Column Phase
Extend-C18
Particle Size
1.8 um
Inner Diameter (ID)
4.6 mm
Length
20 mm
SKU
726700-902
Name
726700-902 - Extend-C18,2.1x20mm,1.8um,600 bar
LC Column Phase
Extend-C18
Particle Size
1.8 um
Inner Diameter (ID)
2.1 mm
Length
20 mm
SKU
724975-902
Name
724975-902 - Extend-C 18 4.6 x 30 mm
LC Column Phase
Extend-C18
Particle Size
1.8 um
Inner Diameter (ID)
4.6 mm
Length
30 mm
SKU
724700-902
Name
724700-902 - Extend-C18 2.1 x 30mm
LC Column Phase
Extend-C18
Particle Size
1.8 um
Inner Diameter (ID)
2.1 mm
Length
30 mm
SKU
5185-5923
Name
5185-5923 - Extend Guard, 1.0x17mm, 5um, 3/pk
LC Column Phase
Extend-C18
Particle Size
5 um
Inner Diameter (ID)
1 mm
Length
17 mm
Key Definitions ▸
Bidentate Bonding
A dual-anchor C18 bonding strategy in which the ligand attaches to the silica surface at two points. This reinforcement significantly improves resistance to hydrolysis and enables operation at elevated pH (up to ~11.5), extending column lifetime in alkaline mobile phases.
High-pH Reversed-Phase LC
A chromatographic mode operating above pH 8 to enhance retention and selectivity for basic analytes. Extend-C18 is engineered specifically for high-pH stability, reducing silica dissolution and preserving bonded-phase integrity.
Double Endcapping
A secondary surface treatment that reduces residual silanol activity, improving peak symmetry— especially for ionizable bases and peptides—while supporting reproducible retention under demanding conditions.
80 Å Pore Size
An optimized pore diameter for small molecules and many peptides. The 80 Å structure balances surface area and mass transfer efficiency, supporting high-resolution separations with controlled backpressure.
Peptide and Basic Compound Analysis
Analytical workflows that benefit from enhanced retention at elevated pH. Extend-C18 improves selectivity and peak shape for peptides and basic small molecules while maintaining compatibility with LC/MS systems.
Frequently Asked Questions ▸
What makes ZORBAX Extend-C18 suitable for high-pH separations?
Extend-C18 is engineered for alkaline mobile phases using reinforced C18 bonding designed to resist hydrolysis and maintain retention reproducibility at elevated pH. This allows high-pH reversed-phase methods (often up to ~pH 11.5, depending on conditions) for basic compounds that can perform poorly at low pH.
When should I choose Extend-C18 instead of a standard C18 column?
Choose Extend-C18 when your method benefits from higher pH (improved retention/selectivity for bases, different elution order, or reduced ion-pairing needs). If your workflow stays in conventional acidic conditions and performance is already strong, a standard C18 may be sufficient.
Is Extend-C18 recommended for peptide LC/MS workflows?
Extend-C18 can be a strong option for certain peptide methods, especially when elevated pH improves retention or selectivity. For peptide mapping, always match pore size to analyte size and confirm recovery/carryover with a reference digest. If peptides are large or show restricted mass transfer on 80 Å, a wider-pore chemistry (e.g., 300 Å) is often a better fit.