Selective fluorogenic derivatization of a peptide nucleic acid trimer with naphthalene-2,3-dicarboxaldehyde

The reversed-phase high-performance liquid chromatography of a Peptide Nucleic Acid (PNA) trimer has been studied after its preseparation fluorogenic derivatization with naphthalene-2,3-dicarboxaldehyde in the presence of cyanide (NDA/CN). Trace levels of the PNA trimer were determined in cell homogenate samples containing the PNA trimer at prederivatization concentrations as low as 48.9 ng ml −1. The sample pretreatment operations included a deproteination step, achieved by ultra-filtration, followed by fluorogenic derivatization (NDA/CN). Subsequently, to achieve adequate selectivity, the fluorescently labeled PNA was subjected to high performance anion exchange chromatography prior to quantitation via fluorescence detection. The various problems encountered during sample pretreatment and separation of derivatized PNA trimer in biological samples are presented and discussed.