ABSTRACT

For analysis of samples by GC, the analytes of interest should be volatile, be thermally stable at the operating temperatures of the injection port and column oven, and give good peak shape. However, it is possible to analyse analytes that do not meet these criteria by carrying out an additional step of sample (and hence compound) pretreatment known as derivatisation. Derivatisation is carried out in order to modify the functionality of an analyte to facilitate separation by GC and is generally used with analytes of low volatility and those that are thermally labile, that is, compounds that could often be analysed by high performance liquid chromatography (HPLC) (Note: For books on HPLC, see Further Reading at the end of the chapter.) Derivatisation is therefore normally done for the following reasons:

• To improve the resolution (see Section 3.2.4) and reduce peak tailing (see Section 3.2.3) of polar compounds; by definition polar compounds contain the following functional groups: –OH, –COOH, =NH, –NH2 and –SH.