An Alternate Derivatization Approach for Efficient Dansylation of Amines in Aqueous Extracts: Toward Quantification of Biogenic Amines in Food Products

Derivatization of amines remains essential for sensitive detection by UV-Vis and mass spectrometric techniques. Among available reagents, Dansyl chloride is widely favored because of its strong fluorescence, high reactivity with amines, and compatibility with reversed-phase LC and MS. In this reaction, the naphthyl chromophore is linked to the target amine through the sulfonyl chloride (–SO₂Cl) group, forming a stable sulfonamide (–SO₂NR–) bond. However, the sulfonyl chloride moiety hydrolyzes readily in aqueous media to produce the corresponding sulfonic acid (R–SO₃H), which is non-reactive toward amines.
Attempts to reproduce conventional aqueous-extract Dansylation procedures yielded inconsistent product formation and weak MS response. To address this, we evaluated an alternate derivatization strategy that reduces the aqueous fraction of the reaction mixture. Preliminary results using putrescine as a model substrate show markedly enhanced ESI-MS signals and improved derivatization efficiency. Ongoing optimization examines the influence of molar ratio, pH, temperature, and reaction time across a range of biogenic amines. The results of these optimization and water-reduction approaches will be presented, demonstrating the potential of controlled-water environments to enhance amine derivatization performance for complex sample matrices.