Reasons for using chemical derivatives in gas chromatography

Having initially led to the development and expansion of derivatization procedures, the above reasons remain important even nowadays, in spite of the fact that their significance for some compounds has decreased owing to the development of modern procedures for the preparation of columns, deactivation and the preparation of modern chromatographic packings. 

It is noteworthy that in practice even the reverse of the above may occur. Often it is necessary to analyse compounds that are too volatile. Significant losses during the preliminary treatment of the sample (e.g., extraction, removal of the solvent), due to this volatility, may introduce errors into the quantitative evaluation. Analysis of volatile carboxylic acids in biological samples is an example. Conversion of these compounds into less volatile derivatives is therefore advantageous from the viewpoint of both GC proper and preliminary isolation of the compounds and sample treatment. 

Many compounds cannot be analysed by GC because of their thermal instability. Such compounds decompose in the injection port of the chromatograph and give several peaks on the chromatogram due to decomposition products. These difficulties also can often be overcome by the use of suitable thermally stable derivatives. 

---