guard columns

[sjmarin]

Does guard column placement matter? It is usually installed just before the analytical column, but would there be any detrimental effect if it was installed further away - say right after the injector?

[skunked_once]

sjmarin,

I have used both types of setup and did not see any significant difference in the applications I was running. The most important thing is to be sure to use the minimum amount of 0.010" tubing between the injector, guard column, and analytical column.

[rc_12321]

I have used it so many times by connecting it before the column,and no problem was observed at any time

[Srinivas SK]

It's not a bad idea to place a guard column before the injector. Actually, such columns are called saturator columns and they serve two purposes - protect the analytical column and protect injector seals.

Usually, silica saturator columns are installed between the pump and injector, to protect reverse phase columns from harsh mobile phase conditions - like extreme pH, high temperature and high buffer salt concentrations.

When used in conjunction with regular guard columns, saturator columns can dramatically increase column life and injector performance.

However, there is a price to pay - higher backpressure and consequent wear and tear on pump components and higher dead volume, that can affect gradient-based analyses.