All C18’s Are Equal - But Some Are More Equal Than Others

Mar 23 2007

Author: Bernie Monaghan on behalf of International Labmate Ltd

Free to read

This article has been unlocked and is ready to read.


Firstly apologies to George Orwell for taking his words in vain however never has the above observation been truer than in the field of HPLC Columns containing the Octadecyl silane (C18 a.k.a ODS or RP-18) hydrophobic grouping bonded chemically to the surface of an amorphous silica surface. These are the most widely used columns in reversed phase chromatography with over 70% of chromatographers choosing this type of column for their separation, often for no better reason than its usually the one supplied with an instrument, or it is the one most likely to be lying around and available from a colleague. Admittedly it is the most stable of all chemistries available to the chromatographer yet stability is not always the prime reason for selecting a column chemistry. So how does a chromatographer decide which C18 column to choose and, as is the norm these days, when a new C18 comes onto the market how different/close is it selectivity wise to other known C18`s? The situation is further complicated by the myriad of exotic endcapping (secondary capping) techniques employed by manufacturers these days. More than 600 Brands on the market make it a potential minefield for the scientist if some help is not at hand to give characterisation clues to indicate the likely success of achieving a desired separation when a degree of knowledge about the analytes is available and the original column specified in the method is either vaguely described or unavailable.

Free to read

This article has been unlocked and is ready to read.


Digital Edition

Lab Asia 31.2 April 2024

April 2024

In This Edition Chromatography Articles - Approaches to troubleshooting an SPE method for the analysis of oligonucleotides (pt i) - High-precision liquid flow processes demand full fluidic c...

View all digital editions



May 28 2024 Tel Aviv, Israel


May 28 2024 Leuven, Belgium

PREP 2024

May 28 2024 Philadelphia, PA, USA


May 29 2024 Beijing, China

ASMS Conference

Jun 02 2024 Anaheim, CA, USA

View all events