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Chromolith® RP-18 Endcapped Monolithic
Silica HPLC Columns


Chromolith® RP-18e HPLC Columns

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Chromolith® RP-18 endcapped HPLC columns Chromolith® RP-18 endcapped columns are the fastest C18 columns in the world. They are ideally suited for fast and robust separation of hydrophobic to medium polar compounds at low column back pressure. Their robustness make Chromolith® RP-18e columns the perfect choice for analyzing matrix-rich samples.

Like all our Chromolith® monolithic HPLC columns, they combine high throughput and lower matrix sensitivity with an extremely long column lifetime. Chromolith® RP-18e columns for reversed-phase chromatography are chemically modified with n-alkyl chains with high ligand density and then fully endcapped in order to minimize the effects of unmodified silanol groups.

In contrast to conventionally packed columns, Chromolith® columns consist of a single piece of high-purity monolithic silica instead of particles. Because of the rigid monolithic silica material, column lifetime is substantially enhanced. The silica used in Chromolith® features an innovative bimodal structure: large macropores for reduced back pressure and fine mesopores for a larger active surface area and better separations. Its high purity reduces the negative effects of trace metals. Moreover, the lower back pressure allows couple several columns for higher resolution.

Easy Method Transfer from Particulate Columns

Just like most high-end particle-packed columns, Chromolith® RP-18 endcapped columns are manufactured from high-purity, metal-free silanes, and they undergo the same surface modification procedures. For this reason, their chromatographic selectivity is very similar to that of high-quality C18 endcapped reversed-phase particulate columns. This makes it very easy to use standard methods when developing new protocols, and to adapt existing methods from particulate columns to monolithic Chromolith® columns.

Chromolith® RP-18e columns are included in the US Pharmacopoeia in category L1.

Features and Benefits

  • High throughput at high flow rates with the best overall column quality
  • Possibility of flow gradients
  • Added column performance by column coupling
  • Rigid monolithic structure for longer column lifetime
  • Lower matrix sensitivity
  • Easy method transfer from particulate columns

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Chromolith® HighResolution RP-18 Endcapped Columns

In addition to its line of standard Chromolith® RP-18e HPLC columns, Merck now provides high-performance Chromolith® HighResolution RP-18 endcapped columns in lengths from 50 to 150 mm. Due to smaller macropores, Chromolith® HighResolution columns offer at least 50% higher efficiency than standard Chromolith® columns, as well as improved peak shape. At the same time, back pressure of HighResolution columns is still less than half that of any particulate column of the same dimensions.

Comparison: Chromolith® RP-18 endcapped HighResolution and Chromolith® RP-18 endcapped

Higher Efficiency, Symmetrical Peaks
Chromolith® Performance
RP-18e, 100-4.6 mm
Chromolith® HighResolution
RP-18e, 100-4.6 mm
Merck:/Freestyle/LE-Lab-Essentials/Chromatography/Diagrams/LE-Chromolith 100-4.6 RP-18e-150x194-11102014.jpg Merck:/Freestyle/LE-Lab-Essentials/Chromatography/Diagrams/LE-Chromolith 100-4.6 HR RP-18e-150x197-11102014.jpg

Mobile Phase Acetonitrile/water 60/40
Flow Rate 2.0 ml/min
Detection UV 254 nm
Temperature Ambient
Inj. Volume 5 µl

1. Urea
2. Biphenyl-2-ol
3. Progesterone
4. Hexanophenone
5. Anthracene

Chromolith® RP-18 Endcapped Standard HPLC Columns

If you need to combine high flowrates, little matrix sensitivity, low back pressure, and long lifetime with even higher efficiency.

Chromolith® RP-18 Endcapped HighResolution HPLC Columns

The ideal choice for fast and robust separation of hydrophobic to medium polar compounds.

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