GC Column Maintenance — Prevention is Better than Cure - - Chromatography Online
GC Column Maintenance — Prevention is Better than Cure



Using proper procedures for capillary GC column storage and conditioning can have a major impact on column lifetime and the quality of results obtained. This "Tips and Tricks" instalment covers everything you wanted to know, but were never told, about proper GC column maintenance.

Column Storage 
Correct column storage is necessary to prevent two major occurrences — the ingress of atmospheric oxygen and moisture into the column and the oxidative degradation of the bonded stationary phase through UV catalyzed mechanisms. The following guidelines will help ensure longer column lifetime:

  • Remember to seal the column ends when they are not in use to exclude atmospheric oxygen and moisture. The easiest way is to seal the column using silicone septa (cut them in half — it’s less expensive!!) or column sealing caps.
  • Don’t leave the column out on the bench where it can be damaged. Store the column so it will not be scratched. If scratched, the stress to the column may cause it to crack during operation.
  • Store the column boxed with the test chromatogram in a dark place. Exposure to high levels of ultraviolet light can initiate oxidization of the stationary phase.

If the column is to remain on the instrument a constant low flow of carrier gas should be maintained with the split flow on.  If the split flow is switched off back diffusion of air into the column can occur; this air can then cause damage.  In order to prevent a build-up of moisture and air in the oven it should be left on at a 
temperature of 60 °C.

Oxygen rapidly degrades the stationary phase by cleaving bonds along the back-bone of the column. This is known as a “cyclic backbiting reaction” where the siloxane chain breaks into more thermodynamically stable, but also more volatile, cyclic siloxanes (Figure 1). It is the elution and detection of these cyclic siloxanes which constitutes column bleed. This damage is irreversible.  The cyclic structures which are formed during this process have characteristic mass spectra at m/z 207, 281, and 355.

The complete article is available to CHROMacademy Lite and Premier members here >>

CHROMacademy Lite Membership is FREE and it only takes two minutes to register.

With a Lite Membership you are given access to:
∙ This month's webcast & tutorial
∙ Selected eLearning modules
∙ Featured CHROMacademy Content
∙ The CHROMacademy forum

Test drive CHROMacademy and Check out more great content available FREE to our Lite members »

ADVERTISEMENT

blog comments powered by Disqus
LCGC E-mail Newsletters
Global E-newsletters subscribe here:




 

LCGC COLUMNISTS 2014

Sample Prep Perspectives | Ronald E. Majors: Ron Majors, established authority on new column technologies, keeps readers up-to-date with new sample preparation trends in all branches of chromatography and reviews developments.
LATEST: UV Detector Problems


Perspectives in Modern HPLC | Michael W. Dong: Michael W. Dong is a senior scientist in Small Molecule Drug Discovery at Genentech in South San Francisco, California. He is responsible for new technologies, automation, and supporting late-stage research projects in small molecule analytical chemistry and QC of small molecule pharmaceutical sciences. LATEST: Superficially Porous Particles: Perspectives, Practices, and Trends


MS — The Practical Art | Kate Yu: Kate Yu brings her expertise in the field of mass spectrometry and hyphenated techniques to the pages of LCGC. In this column she examines the mass spectrometric side of coupled liquid and gas-phase systems. Troubleshooting-style articles provide readers with invaluable advice for getting the most from their mass spectrometers. LATEST: Radical Mass Spectrometry as a New Frontier for Bioanalysis


LC Troubleshooting | John Dolan: LC Troubleshooting sets about making HPLC methods easier to master. By covering the basics of liquid chromatography separations and instrumentation, John Dolan is able to highlight common problems and provide remedies for them. LATEST: Problems with Large-Molecule Separations


More LCGC Chromatography-Related Columnists>>

LCGC North America Editorial Advisory Board>>

LCGC Europe Editorial Advisory Board>>

LCGC Editorial Team Contacts>>



Click here