High-pressure-resistant, base-resistant columns for UHPLC

Wakopak® Ultra Series (C18)


Wakopak® Ultra C18 is an ODS column with improved packing agent surface treatment technology and reduced residual silanol groups to the extreme. It is also highly durable in basic eluents above pH 9 that were difficult with other Wakopak® C18 series.
Wakopak® Ultra C18-2 has a particle size of 2 μm for UHPLC.
Wakopak® Ultra C18-5 with 5 μm particle size and Ultra C18-3 with 3 μm particle size which has a same HPLC performance as Wakopak® Ultra C18-2. So it is possible to transfer the analytical conditions easily from HPLC to UHPLC.


Silica Gel High-purity spherical silica gel
Average Particle Size 2 µm, 3 µm, 5 µm
Specific Surface Area 320 - 360 m2/g
Pore Size 2 µm: 9.0-11.0 nm
3 µm,5 µm: 11.0-14.0 nm
Pore Volume 2 µm: 0.80 - 0.90 mL/g
3 µm, 5 µm: 0.95 - 1.15 mL/g
Functional Group Octadecyl group
Carbon Content 15.0 - 16.5%
USP Code L1
Recommend pH Range 1.5 - 10.0


  • Robust columns without deterioration
  • The peak shape of basic compounds is sharp
  • Available over a wide pH range (pH1.5-10)
  • Available for UHPLC (Wakopak® Ultra C18-2)


Example of analysis in a basic eluent

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  • HPLC Conditions
    Column Wakopak® Ultra C18-5、 4.6 mm x 150 mm
    Eluent 10 mM Sodium Tetraborate (pH9.2)/CH3OH=62/38 (v/v)
    Flow Rate 1.0 mL/min. at 45℃
    Detection 510 nm
    Sample 1. Cobalt-PAR Complex (Co-PAR)
    2. Unreacted-PAR reagent (PAR)
    Inject. Vol 10 μL

Example of separation of basic compounds

  • 00480_img03.png
  • Common Conditions
    Eluent CH3CN/10 mM K2HPO4 (pH7.6)=70/30 (v/v)
    Detection UV 254 nm
    Sample 1. Uridine 2 mg, 2. Procainamide HCl 5 mg, 3. Phenol 20 mg,
    4. 2,4,6-Trimethylpyridine 10 μL, 5. Methyl benzoate 50 μL in 100 mL 30% CH3CN
    Inject. Vol 1 μL

Example of analysis of non-ionic surfactants

"Wakopak® Ultra C18" is available over a wide pH range by improving the surface treatment technology of the silica gel packing agent. Maintenance of at least 85% of the initial retention performance was confirmed, even after 1,500 hours or more of continuous use under below analytical conditions (using an eluent with a pH of 9.2), and the product can be used continuously.


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Column for HPLC: Wakopak® Ultra C18-3 (Pore Size: 3 μm)

D: DuPont type, W: Waters type
*Made to order product

Column for HPLC: Wakopak® Ultra C18-5 (Pore Size: 5 μm)

D: DuPont type, W: Waters type
*Made to order product

Column for HPLC: Wakopak® Ultra C18-2 (Pore Size: 2 μm)

For research use or further manufacturing use only. Not for use in diagnostic procedures.

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If the revision of product standards and packaging standards has been made, there is a case where the actual product specifications and images are different.


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