Gas Chromatography Columns

What is the difference between packed and capillary columns? Or Basic about Gas Chromatography Columns.

There are mainly two type of column used in the Gas Chromatography as a stationary phase:

  1. Packed Column
  2. Capillary Column

Basic of this column as described below,

1. Packed column:

  • A packed column is one that has a densely packed stationary phase made up of fine particles.
  • It’s made of stainless steel or a glass tube with particle packing material within (an adsorbent material, or a support material coated or impregnated with a solid phase).

Material Used in Packed Column: Zeolites

 GC Packed column

Read: Principle of HPLC (Liquid Chromatography), Calibration of HPLC

2. Capillary column:

  • Also known as WCOT (Wall Coated Open Tubular), or PLOT (Porous Layered Open Tubular).
  • A capillary column is one that has a stationary phase coated on the inner surface.
  • Coateing material includes:
  • Methyl silicone
  • Phenylmethyl
  • Cyanopropyl phenol
  • Trifluoropropyl
  • Polyethylene glycol Methylpolysiloxane
  • Trifuoropropylmethylpolysiloxane
  • Bis-cyanopropyl
  • Cyanopropylphenylpolysiloxane
GC Capillary column
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Related: Handling of HPLC and GC Columns, Preparation and Standardization of 0.1 N Hydrochloric Acid (0.1 N HCl)

In Gas Chromatography (GC), why are Columns chosen over Packed Columns?

  • Gas Chromatography Columns: Packed columns generate broad peaks and capillary columns generate sharp peaks in GC analysis.
  • Capillary columns also yield taller peaks, allowing for the detection of lower concentrations (high detection sensitivity). Capillary columns have this advantage. Capillary column produce more theoretical plates (N) than a packed column.
  • Capillary column can be used with mass spectrometers because of narrower ID’s.
  • New era GC’s designed mostly for use with capillary columns.
  • Capillary columns are used in most current methods.


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