Synthesis of 3-Mehoxy-4-hydroxybenzaldehyde-2-hydrazinobenzoic Acid and Its Fluorescence Quenching Reaction with Silver Ion

A new fluorescence reagent,3-mehoxy-4-hydroxybenzaldehyde-2-hydrazinobenzoic acid (MHBHBA) was synthesized and its molecular structure was identified by IR-spectrometry and elementary analysis.It was found that in an acetate buffer of pH 5.1,the new reagent,MHBHBA reacted with Ag+ ion to form a stable complex,leading to quenching of fluorescence of the reagent,and that the magnitude of fluorescence quenching of MHBHBA kept linear relationship with mass concentration of Ag+ ion in the range of 3.0-160 μg·L-1,when measured at the wavelengths of (λex) 308.8 nm and (λem) 476.8 nm.Detection limit (3S/N) found was 0.28 μg·L-1.Based on these facts,method for determination of trace amount of silver was proposed.Recovery of the method was tested by standard addition method,giving values of recovery ranged from 98.3% to 103.3%.