Derivatization of formaldehyde with dimedone and subsequent sorption on sodium dodecylsulfate/alumina admicelles for fluorometric analysis.

The reaction of formaldehyde with β-diketones (Hantzsch reaction) has been often employed for derivatizing formaldehyde to the fluorescent compounds.1,2 Among βdiketones, 5,5-dimethyl-1,3-cyclohexanedione (dimedone, Fig. 1) seems to be the most promising because of the strong fluorescence intensity and stability of the formed compound. Recently, we developed a method for concentrating trace hydrophobic analytes in water.3–5 Any hydrophobic substances in the aqueous solution were efficiently incorporated into the hydrophobic region of surfactant aggregates formed on solid surfaces. Particularly, sodium dodecylsulfate (SDS)-modified γ-alumina (termed by SDS/alumina admicelle) was the best choice for collecting hydrophobic compounds because of its stability and highly hydrophobic property.6 The present communication describes the feasibility of a new combination of the Hantzsch reaction and an admicellemediated concentration method. Because of the hydrophobic property of the derivatized compound, it was expected to be well sorbed onto SDS/alumina admicelles. The requisites for obtaining good fluorescence signals were also studied.