Abstract:

A novel fluorescein derivative, 5-bromosalicylicaldehyde fluorescein hydrazone(BSFH), has been synthesized by reacting fluorescein hydrazine with 5-bromosalicylicaldehyde and characterized by IR, NMR, MS, elemental analysis. The selectivity of BSFH to common metal ions in aqueous solution was investigated by absorption spectroscopy. BSFH has almost no absorption in visible region and very low absorption at 496 nm with addition of other metal ions except Cu²⁺. However, in the presence of Cu²⁺, a rapid color change of BSFH from colorless to yellow along with a very obvious absorption appears at 496 nm in the absorption spectrum. The absorbance of BSFH at 496 nm increases gradually with the increase of Cu²⁺. The selective binding of BSFH to Cu²⁺ over other metal ions is remarkably high in the aqueous solution. Experimental results indicate that the chemical stoichiometric ratio between BSFH and Cu²⁺ is 1:1, the linear range of detecting Cu²⁺ concentration is 0.30~10 μmol/L, common metal ions do not show any interference on the determination of Cu²⁺, the detection limit is 0.30 μmol/L, and BSFH is highly sensitive to Cu²⁺ in the aqueous solution. Therefore, BSFH can be utilized to detect Cu²⁺ at low concentration with simple, rapid and sensitive method.

Key words: fluorescein derivative, bromosalicylicaldehyde fluorescein hydrazone, cupper(Ⅱ) ion, absorption spectrum, detection