Fluorospectrophotometric Determination of Dimethoate with Calcein-Pd²⁺ as Fluorescence Probe

In a phosphate buffer medium of pH 7.98,a complex with mole ratio of 1 to 1,was formed by the reaction of Pd2+ with calcein,leading to fluorescence quenching of the reagent. Upon addition of dimethoate to the above solution,a more stable complex was formed by the reaction of dimethoate with Pd2+,and calcein was displaced from the calcein-Pd2+ complex,leading to resumption of its fluorescence. It was found that linear relationship between the magnitude of increase in fluorescence intensity and mass concentration of dimethoate was kept in the range of 0.2-1.2 mg·L-1 when measured at the wavelengths of 490 nm (λex) and 512 nm (λem). Based on these facts,a sensitive method for fluorospectrophotometric determination of dimethoate was proposed with calcein-Pd2+ as fluorescence probe. Recovery of the method was tested by standard addition method,and the values of recovery obtained were ranged from 82% to 108%.