Phase for Highly Aqueous Eluents

  • Stable in 100% aqueous mobile phase systems-USP L1
  • Pore size 110 Å; particle sizes 1.8 µm, 3 µm and 5 µm; 14 % C
  • 7 and 10 µm particles for preparative purposes are available on request
  • Interesting polar selectivity features
  • Excellent base deactivation; suitable for LC/MS due to low bleeding characteristics
  • pH stability 1-9
  • Classes of compounds separated so far: analgesics, penicillin antibiotics, nucleic acid bases, water-soluble vitamins, complexing agents, organic acids

RP-HPLC with highly aqueous mobile phases
The efforts to neutralize unwanted activity of unreacted surface silanol groups often results in well base-deactivated phases with high carbon load, but a limited scope of selectivity beyond non-polar interactions. In particular polar compounds like carboxylic acids, drug metabolites, etc. show only weak retention on densely bonded reversed phase columns due to distinct hydrophobic properties but low polar interactions. Very polar analytes require highly aqueous mobile phases for solubility and retention. Conventional reversed phase columns often display stability problems in eluent systems with high percentage of water (> 95%) as evidenced by a sudden decrease of retention time and overall poor reproducibility. This phenomenon is described as phase collapse caused by the mobile phase expelled from the pores due to the fact, that hydrophobic RP phases are incompletely wetted with the mobile phase.

Different approaches can be used to increase column stability with highly aqueous mobile phase systems. The most promising concepts are incorporating a polar group in the hydrophobic alkyl chain, or using hydrophilic endcapping procedures to improve the wettability of the reversed phase modification. NUCLEOSIL® Nautilus may be taken as an example for the embedded polar group strategy, in which a C18 silane with a polar function is successfully linked to the silica surface.

Stability Features
NUCLEODUR® C18 Pyramid is a silica phase with hydrophilic endcapping, designed especially for use in eluent systems of up to 100% water. The figure below shows the retention behaviour of tartaric, acetic and maleic acid under purely aqueous conditions on NUCLEODUR® C18 Pyramid in comparison with a conventionally bonded RP phase. It can be shown that the retention times for NUCLEODUR® C18 Pyramid remain nearly unchanged between initial injection and restart after the flow has been stopped for 12 hours, whilst the performance of the conventional RP column collapsed totally after the same period.

Retention characteristics
The polar surface derivatization exhibits retention characteristics, which differentiate the "Pyramid" from conventional C18 stationary phases. The chromatogram below shows the improved retention behaviour of very polar compounds such as short chain organic acids, which are insufficiently retained on RP columns with predominantly hydrophobic surface properties.



NUCLEODUR® C18 Pyramid, 3um

Catalog #/DescriptionAdd to Cart/List Price
760263.20 - MN HPLC Column, Nucleodur C18 Pyramid, 100A, 3um, 2x50mmAdd to Cart  662.00
760263.30 - MN HPLC Column, Nucleodur C18 Pyramid, 100A, 3um, 3x50mmAdd to Cart  663.00
760263.40 - MN HPLC Column, Nucleodur C18 Pyramid, 100A, 3um, 4x50mmAdd to Cart  663.00
760263.46 - MN HPLC Column, Nucleodur C18 Pyramid, 100A, 3um, 4.6x50mmAdd to Cart  723.00
760261.20 - MN HPLC Column, Nucleodur C18 Pyramid, 100A, 3um, 2x150mmAdd to Cart  758.00
760261.30 - MN HPLC Column, Nucleodur C18 Pyramid, 100A, 3um, 3x150mmAdd to Cart  770.00
760261.40 - MN HPLC Column, Nucleodur C18 Pyramid, 100A, 3um, 4x150mmAdd to Cart  770.00
760261.46 - MN HPLC Column, Nucleodur C18 Pyramid, 100A, 3um, 4.6x150mmAdd to Cart  839.00
760262.20 - MN HPLC Column, Nucleodur C18 Pyramid, 100A, 3um, 2x250mmAdd to Cart  874.00
760262.30 - MN HPLC Column, Nucleodur C18 Pyramid, 100A, 3um, 3x250mmAdd to Cart  868.00
760262.40 - MN HPLC Column, Nucleodur C18 Pyramid, 100A, 3um, 4x250mmAdd to Cart  868.00
760262.46 - MN HPLC Column, Nucleodur C18 Pyramid, 100A, 3um, 4.6x250mmAdd to Cart  918.00


NUCLEODUR® C18 Pyramid, 5um

Catalog #/DescriptionAdd to Cart/List Price
760200.20 - MN HPLC Column, Nucleodur C18 Pyramid, 110A, 5um, 2x50mmAdd to Cart  528.00
760200.30 - MN HPLC Column, Nucleodur C18 Pyramid, 110A, 5um, 3x50mmAdd to Cart  531.00
760200.40 - MN HPLC Column, Nucleodur C18 Pyramid, 110A, 5um, 4x50mmAdd to Cart  531.00
760200.46 - MN HPLC Column, Nucleodur C18 Pyramid, 110A, 5um, 4.6x50mmAdd to Cart  580.00
760201.20 - MN HPLC Column, Nucleodur C18 Pyramid, 110A, 5um, 2x125mmAdd to Cart  609.00
760201.30 - MN HPLC Column, Nucleodur C18 Pyramid, 110A, 5um, 3x125mmAdd to Cart  620.00
760201.40 - MN HPLC Column, Nucleodur C18 Pyramid, 110A, 5um, 4x125mmAdd to Cart  620.00
760201.46 - MN HPLC Column, Nucleodur C18 Pyramid, 110A, 5um, 4.6x125mmAdd to Cart  668.00
760203.46 - MN HPLC Column, Nucleodur C18 Pyramid, 100A, 5um, 4.6x150mmAdd to Cart  668.00
760202.20 - MN HPLC Column, Nucleodur C18 Pyramid, 110A, 5um, 2x250mmAdd to Cart  701.00
760202.30 - MN HPLC Column, Nucleodur C18 Pyramid, 100A, 5um, 3x250mmAdd to Cart  697.00
760202.40 - MN HPLC Column, Nucleodur C18 Pyramid, 100A, 5um, 4x250mmAdd to Cart  697.00
760202.46 - MN HPLC Column, Nucleodur C18 Pyramid, 100A, 5um, 4.6x250mmAdd to Cart  738.00


NUCLEODUR® C18 Pyramid, Guard Cartridges

Catalog #/DescriptionAdd to Cart/List Price
761915.20 - MN HPLC Guard Cartridges, Nucleodur C18 Pyramid, 1.8um, 2x4mm, 3/pkAdd to Cart  138.00
761915.30 - MN HPLC Guard Cartridges, Nucleodur C18 Pyramid, 1.8um, 3x4mm, 3/pkAdd to Cart  138.00
761916.20 - MN HPLC Guard Cartridges, Nucleodur C18 Pyramid, 3um, 2x4mm, 3/pkAdd to Cart  138.00
761916.30 - MN HPLC Guard Cartridges, Nucleodur C18 Pyramid, 3um, 3x4mm, 3/pkAdd to Cart  138.00
761917.20 - MN HPLC Guard Cartridges, Nucleodur C18 Pyramid, 5um, 2x4mm, 3/pkAdd to Cart  138.00
761917.30 - MN HPLC Guard Cartridges, Nucleodur C18 Pyramid, 5um, 3x4mm, 3/pkAdd to Cart  138.00