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Decomposition in the column? The Peak shape will tell!

25 Jun 2009

diagram

Gas chromatography can be used widely, but when components get thermolabile we have to be careful. When a component decomposes while it is traveling through the column, the peak shape will tell us. The component will decompose most of the time into a more volatile component that elutes faster from the column. We observe a typical peak shape as shown in the figure: the peak shows a strong “lead”.

The example shown here is a flame retardant. There components are designed to decompose but we have to keep them in shape to quantify them. This can be done by reducing the elution temperature. If BDE elutes below 295C, the peak will be near symmetrical.

Ways to reduce decomposition in the column:

  • Use higher flow rate, a flow program or a pressure program.
  • Use a slower temperature program
  • One can also use hydrogen as the carrier gas instead of helium.
  • Use columns with thinner films: Use a capillary with a 0.32mm internal diameter
  • Use shorter columns