3. Formation of pre- or post-chromatography derivatives

When the solute has no chromophore groups suitable for spectrophotometric detection, it must be transformed with a specific reagent.

• This can be done prior to chromatography [14] ; in this case, the reaction must give stable products and, if possible, a single product in very high yield. In addition, there must be no chromatographic interference between the reagent and the derivative formed. The reactions used are :

  • oxidation or reduction using hydrogen peroxide, sodium periodate, chromic acid, iodine or palladium chloride, sodium borohydride, etc. ;

  • hydrolysis, which may be chemical or enzymatic; zone concentration plates are well suited to the latter technique;

  • ...