Guanhong Liu, Peipei Ren, Xuekai Dou, Jun Wang, Youtao Song, School of Environment

Fan Yang, College of Chemistry

Abstract: Two novel isomeric colorimetric probes are established for simultaneous determination of copper ions using 2-Hydroxy-5-methoxybenzaldehyde fluorescein hydrazone (5-HMBA-FH) and 2-Hydroxy-3-methoxybenzaldehyde fluorescein hydrazone (3-HMBA-FH). They are synthesized by reacting fluorescein hydrazide with 2-Hydroxy-5-methoxybenzaldehyde and 2-Hydroxy-3-methoxybenzaldehyde, respectively, and then characterized by ¹H-NMR, ¹³C-NMR and Infrared spectrum. In addition of copper ions to the solutions of two novel colorimetric probes can generate the obviously peaks at 498 nm in UV-vis absorption spectra along with a rapid color change from colorless to dark yellow. The detection limits of the method for Cu²⁺ ion were 3.442 × 10^-6 mol/L and 3.682 × 10^-6 mol/L separately, for 5-HMBA-FH and 3-HMBA-FH. The additions of other metal ions hardly affect the copper ions determination. The proposed method was successfully applied to the analysis of Cu²⁺ ions in various samples. This method possessing high sensitivity, simplicity and minimized interfere will provide a great advantage in detecting copper ions in the environmental, food, medical  applications.

Read the article here:   138-Two novel colorimetric probes (5-HMBA-FH and 3-HMBA-FH) based on fluorescein for copper(II) ion detection.pdf