ZORBAX Bonus-RP Columns

Agilent ZORBAX Bonus-RP Columns

Agilent ZORBAX Bonus-RP columns deliver exceptional reversed-phase performance for challenging basic compounds, offering a unique selectivity profile that extends well beyond traditional C18 and C8 phases. Engineered with an embedded polar amide group and triple endcapping, these columns minimize unwanted secondary interactions with silica, ensuring cleaner peak shapes, improved resolution, and superior reproducibility at low and mid-pH conditions.

  • Excellent peak shape for difficult basic analytes—even under acidic and mid-pH conditions.
  • Unique reversed-phase selectivity that complements and extends beyond conventional C18 and C8 columns.
  • Embedded polar amide group + steric protection for reduced silanol interactions and improved stability.
  • Fully compatible with 100% aqueous mobile phases for robust retention of polar analytes.

The Bonus-RP bonding chemistry combines a long alkyl chain with an internal amide group, dramatically reducing interaction between basic compounds and exposed silica sites. This design enhances peak symmetry for amines, heterocycles, and other problematic analytes. Diisopropyl side chains provide steric shielding against acid hydrolysis, improving durability under low-pH conditions where conventional columns rapidly degrade.

Whether you're developing new methods or optimizing difficult separations, ZORBAX Bonus-RP provides a powerful alternative selectivity option with excellent lifetime, stability, and consistency across complex sample types.

For assistance selecting the right ZORBAX column for your workflow, contact Chrom Tech and our technical specialists will help you find the best fit for your application.

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SKU Name LC Column Phase Particle Size Inner Diameter (ID) Length
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
821125-928
Name
821125-928 - Bonus-RP NB Guard Cart 5u 2.1x12.5mm 4PK
LC Column Phase
Bonus-RP
Particle Size
5 um
Inner Diameter (ID)
2.1 mm
Length
13 mm
SKU
820212-928
Name
820212-928 - PrepHT,Zorbax,Bonus-RP,Grd Crt,5um,2/PK
LC Column Phase
Bonus-RP
Particle Size
5 um
Inner Diameter (ID)
17 mm
Length
8 mm
SKU
5185-5922
Name
5185-5922 - Bonus-RP Guard, 1.0x17mm, 5um
LC Column Phase
Bonus-RP
Particle Size
5 um
Inner Diameter (ID)
1 mm
Length
17 mm
Key Definitions ▸
Embedded Polar Group (EPG)
A polar functional group built into the reversed-phase ligand. In Bonus-RP style chemistries, the embedded polar group can reduce unwanted silanol interactions, improve peak shape for basic compounds, and support stable retention under highly aqueous starting conditions.
Steric Protection
A design approach that uses bulky groups to help shield the silica–ligand bond from hydrolytic attack. Steric protection is commonly associated with improved durability in aggressive mobile-phase conditions and extended column lifetime.
(Multi-)Endcapping
A surface treatment used to neutralize residual silanol groups on silica. Strong endcapping strategies improve peak symmetry (especially for ionizable bases), reduce tailing, and increase method-to-method reproducibility across pH and buffer systems.
100% Aqueous Compatibility
The ability of a reversed-phase column to maintain consistent retention and avoid phase collapse when operating at (or near) 100% water. This is important for polar analytes and methods that start at very high aqueous content.
Alternate Selectivity (Bonus-RP)
A retention profile that differs from traditional C18/C8 phases. Bonus-RP phases are often chosen to improve resolution for polar, basic, and aromatic compounds by introducing additional interaction types beyond purely hydrophobic retention.
Frequently Asked Questions ▸
What makes Agilent ZORBAX Bonus-RP columns different from traditional C18 phases?
Bonus-RP is designed to deliver alternate reversed-phase selectivity by adding a built-in polar interaction component (embedded polar group) to the ligand architecture. This often improves peak shape for ionizable bases and increases retention of polar analytes compared with many conventional C18 phases—without leaving standard reversed-phase workflows.
Can Bonus-RP columns operate in 100% aqueous mobile phases?
Bonus-RP is commonly selected for high-aqueous starting conditions and very polar compounds because the embedded polar group helps stabilize retention when organic content is low. For best reproducibility, equilibrate thoroughly after large solvent changes and use consistent buffer strength and temperature.
Are Bonus-RP columns suitable for low-pH separations?
Bonus-RP methods are frequently run at low-to-mid pH, where improved peak shape for basic compounds can be especially valuable. Always confirm the recommended pH and temperature limits for your exact column format and particle size, since lifetime depends on mobile-phase composition, buffer type, and operating temperature.
When should I choose Bonus-RP over SB-C18 or Eclipse Plus?
Choose Bonus-RP when you need (1) stronger retention for polar compounds, (2) a selectivity “reset” when C18/C8 phases can’t resolve a critical pair, or (3) improved peak symmetry for challenging bases. If your primary requirement is extreme low-pH robustness, StableBond is often the better first choice; if you want a general-purpose C18 with consistently strong peak shape for a wide range of analytes, Eclipse Plus is a common baseline.