Abstract

Spectrophotometric methods using organic reagents are among the most used methods because of their rapid, simplicity, low cost, and wide range of applications. This research studied the possibility of forming a colored complex between Zinc (II) and the reagent 4-Hydroxy – 3 -[[hydroxy phenyl) methylene] amino] benzene sulphonic acid II to determine Zinc (II) in aqueous solutions by spectrophotometric method. This research aimed to use the reagent to determine zinc (II) in aqueous solutions using the spectrochromatic method by forming a stable and colored complex with it, determining the limit of detection, studying the spectral properties of the formed complex, and then comparing it with other organic reagents. The method focused on the following sections: choosing pH and optimum temperature, testing some organic solvents and choosing the optimum solvent, determining the molar ratio, determining the molar absorption coefficient and stability constant, determining the optimal reagent concentration and sequence of additions, liner range, and studying the effect of blocked ions. Finally, we tested the method on prepared lab samples for Zinc (II). It was observed from the practical experiments that the reagent reacts with Zinc ions in Britton buffer medium (pH=9) at room temperature to form a Yellow-greenish complex λmax=415). The composition of complex is [(Zn:L)-(1:4)] and the molar absorption coefficient and stability constant are calculated and found to be ε=2.88×104l.mol-1.cm-1 and βk =2.15×103. Calibration was linear over the range (0.1-6) mg/l and the detection limit was 0.02 mg/l. The proposed method was examined on standard solutions of Zinc, and RSD% in the range (0.41-4.56)%, and the recovery ( 91-101.8 )%. We conclude from the results that the method is valid and accurate and that the proposed reagent can be used to determine Zinc ions.