Post-chromatographic derivatization in liquid chromatography

In liquid chromatography, including HPLC, Schlabach and Weinberger [15] classify analytes as co-operative if they lend themselves to methods of detection such as UV or visible absorption, fluorescence, changes in refractive index, electrochemical detection or other instrumental procedures. Analytes are classed as nonco-operative if such detection methods are not applicable or lack the necessary sensitivity, and in general it is such analytes that are the prime candidates for post-chromatographic derivatization. The scope of post-chromatographic procedures is summarized in Table 2. 

Post-chromatographic photochemical derivatization Solid-phase reactors Electrochemical methods 

Liquid chromatographic systems are particularly suited to post-chromatographic derivatization, because the vast majority of chemical reactions are done in solution or in the liquid phase. Another reason in that liquid chromatographic separations can very often be achieved without any need for derivatization before the chromatographic step, whereas derivatization may be needed for detection or quantitation (or both) afterwards. 

Generally speaking, derivatization of the components separated by the column is achieved by the addition of reagent solutions to the column effluent, which is straightforward because the pressure of the effluent at the end of the column is much lower than the inlet pressure. In order to meet the objectives of Table 1, there are a number of other requirements, which are listed in Table 3. 

Derivatization manifolds make use of a variety of fittings which are connected together between the 

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Table 2 Post-chromatographic derivatization in liquid chromatography...

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