Why is Conditioning necessary for GC Columns?

Conditioning is a process involving flow of carrier gas through a GC column at elevated temperature to flush out residual contaminants and make it fit for reliable use.

Packed Column

Packed Column

Impurities such as oxygen and water have a potential of causing irreversible damage to stationary phase at elevated temperatures during operation and shorten the useful lifetime of a GCcolumn.

Temperature Requirement for Conditioning

Initial purging at room temperature serves to remove traces of oxygen and moisture from GC column and injector.

Every GC column has two temperature limits:

Isothermal maximum is the temperature a column can tolerate for extended periods of time

Maximum temperature is the temperature that a column can sustain for short periods, typically less than 10 min without any damage to stationary phase.

For the purpose of conditioning the isothermal maximum temperature should not be exceeded.

Time requirement for conditioning

The flow rate, inlet pressure and conditioning time depend on GC column dimensions. Generally conditioning can be completed in 1-2 hours but GC columns having longer lengths (> 30 m) or with thicker film packings (>0.5 μm) may require longer conditioning. Overnight conditioning is not always necessary. Use of high sensitivity detectors such as mass spectrometer can also necessitate longer conditioning times.

Necessity for Conditioning

All new GC columns are shipped after preconditioning but it is advisable to recondition them prior to use. Unconditioned GC columns contribute to excessive baseline noise which becomes difficult to suppress.

GC columns should be conditioned before use as they can contain volatile components from the inner wall coating process. Capillary GC columns contain lesser quantity of stationary phase but conditioning is advisable for these GC columns as well.

A packed column which has been stored for some time without end caps or plugs can get contaminated with impurities present in the air and should be conditioned prior to use.

It can be seen that you will face lesser problems when you use conditioned columns before starting analysis. It takes a few hours to condition GC columns but you can save several hours of your valuable time subsequently.

Please do share your experiences if you have used unconditioned GC columns and leave your comments.

About Dr. Deepak Bhanot

Dr Deepak Bhanot is a seasoned professional having nearly 30 years expertise beginning from sales and product support of analytical instruments. After completing his graduation and post graduation from Delhi University and IIT Delhi he went on to Loughborough University of Technology, UK for doctorate research in analytical chemistry. His mission is to develop training programs on analytical techniques and share his experiences with broad spectrum of users ranging from professionals engaged in analytical development and research as well as young enthusiasts fresh from academics who wish to embark upon a career in analytical industry.

Comments

  1. SARVESH GUTPA says:

    Really this is a very good topic, i have learnt one new things that is very useful for us.

  2. Good article…however, how frequently should I condition my GC columns? After every analysis? I usually just “bake” it for about 20mins before every analysis. I use a GC-FID.

    • Hi Jarvis,
      A column does not require reconditioning after every analysis unless you have overloaded your column with a strongly retained mixture of compounds.Reconditioning should be resorted to in case you observe shifts or peak distortions in your chromatograms otherwise it is a waste of your precious time.

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