In the current work, the azo ligand and its Pd (Ⅱ), Cd (Ⅱ), Zn (Ⅱ) and Hg (Ⅱ) complexes were synthesized, characterized and their spectroscopic characteristics were studied. The new ligand was synthesized from the coupling reaction between 4,5-bis(4-methoxy phenyl)imidazole and the diazonium salt of 4-Amino benzoic acid in an alkaline medium at 0-5 ᵒC. the new azo metal complexes were prepared by the reaction between the ligand and metals chlorides. All the synthesized compounds were characterized by FT-IR, 1H-NMR, Mass spectral analysis, UV-Vis spectrophotometric, molar conductivity, and magnetic sensitivity. The biological activity of the azo ligand and its Pd (Ⅱ) complex was also studied. keywords: Azo compound, 4,5-di (4-methoxy phenyl) imidazole, azo metal complexes

The objective of the present work is to develop batch and merging-zone flow injection methods for sensitive and accurate spectrophotometric determination of tetracycline hydrochloride. The methods depend on the oxidation of the studied drug with potassium permanganate in an alkaline medium, and the absorbance of the green oxidation product was measured at 610 nm. The calibration graphs in both procedures were linear in the concentration ranges of 0.5 – 25 and 1 – 25 μg mL−1 using the spectrophotometric and merging-zone flow injection methods, respectively. Specific and molar absorption coefficients, limits of detection and quantification, and Sandell’s sensitivity were calculated. The suggested procedures were further applied to the quantitative determination of tetracycline in pharmaceutical formulations.