Derivatization is a technique that can be used to increase sensitivity and chromatographic performance for specific compounds.
Compounds such as acids, alcohols and amines are difficult to analyse because of the presence of reactive hydrogens. When attempting to analyse these types of compounds, they can react with the surface of the injection port or the analytical column and result in tailing peaks and low response.
In addition, they may be highly soluble in the sample phase, causing very poor partitioning into the headspace and low response. Derivatization can improve their volatility, as well as reduce the potential for surface adsorption once they enter the GC system.
|Common reagents used to derivatize compounds of interest:|
|Compound of Interest||Derivatizing Reagent||Resulting Derivative|
|fatty acids||methanol with boron trifluoride||esterfication|
|glycerol||acetic anhydride with sodium carbonate||acetylation|
Common derivatization techniques used in reaction headspace/GC are:
Any of these derivatization techniques can be performed using the sample vial as the reaction vessel. Although derivatization may improve chromatographic performance and volatility for some compounds, derivatization reactions may introduce other problems into the analytical scheme: