Standard Reversed Phase Columns

The reversed phase HPLC column is most commonly used because of the high theoretical plate number, excellent separation characteristics, reproducibility, affordable cost and ease of use. Columns packed with the octadecyl group bonded type silica gel (C18, ODS) are the most widely employed. We offer three types of octadecyl group bonded columns: COSMOSIL 3C18-EB, C18-MS-II, C18-AR-II and C18-PAQ, each of which has a different separation property.



Packing Material 3C18-EB C18-MS-II C18-AR-II C18-PAQ
USP Code L1 L1 L1 L1
Silica Gel High Purity Porous Spherical Silica
Average Particle Size 3 µm 3, 5, 15 µm 5, 15 µm
Average Pore Size approx. 120 Å
Specific Surface Area approx. 300 m2/g
Stationary Phase Stationary phase C18-MS-II Stationary phase C18-AR-II C18-PAQ
Octadecyl Group
Bonding Type Monomeric Polymeric
Main Interaction Hydrophobic Interaction
End Capping Treatment Near-perfect Treatment
Carbon Content approx. 14.5% approx. 16% approx. 17% approx. 11%
pH Range 2-10* 1.5-7.5* 2-7.5
Feature This phase with a better end-capping treatment offers improved peak shape and separation particularly
for basic compounds.
This phase is recommended for most applications but particularly effective for basic compounds. This phase is recommended for separations requiring acidic mobile phase conditions. It also shows superior molecular shape selectivity to monomeric type C18columns. This phase is designed to offer superior retention of polar compounds and excellent reproducibility in highly aqueous mobile phases, even in 100% aqueous.

Optimum pH range of columns based on silica gel is between 2 and 7.5.

Column Selection by Mobile Phase

  • If a mobile phase is determined, use the following chart to select an appropriate COSMOSIL column.
  • Refer to application data above for choosing a mobile phase of new analysis.
  • Adjustment of pH is required for dissociative compounds.
  • Generally acidic mobile phase is suitable for acidic compounds, and neutral mobile phase is suitable for basic compounds.
  • If you are not sure about the mobile phase, try C18-MS-II first.

Mobile Phase

Product Information

Deference of Separation Property

Deference of separation property

Column Size 4.6 mm I.D. x 150 mm Sample 1. Valerophenone (0.17 µg)
Mobile Phase Methanol : Water = 80 : 20 2. Butyl Benzoate (0.17 µg)
Flow Rate 1.0 ml/min 3. Butylbenzene (8.0 µg)
Temperature 30°C 4.o-Terphenyl (0.17 µg)
Detection UV 254 nm 5. Amylbenzene (8.0 µg)
6. Triphenylene (0.021 µg)


Column Selection Based on Application

We prepare following application data to help you select separation conditions.

COSMOSIL Application

COSMOSIL Application Search

COSMOSIL Application, which includes more than 7,000 applications using COSMOSIL columns, is now available. 
The application is searchable by sample category, sample name, CAS No., column name and particle size.

USP Application

Applications in accordance with U.S. Pharmacopoeia Methods

Application of USP Standars using COSMOSIL columns in accordance with the conditon specfied in USP-PF(Pharmacopoeial Forum) online is available.

JP Applications

Applications of Substances in the Japanese Pharmacopoeia, 15th

Data of drugs using three kinds of C18 columns that are specified in HPLC analysis in Application Data of Substances in Japanese Pharmacopoeia, 15th version is available.