Derivative UV Spectrophotometric Analysis of Some Pharmaceutically Important Halogenated 8-Hdroxyquinoline Derivatives via Their Pd (II)-Complexes

A derivative UV-spectrophotometric method was developed for the analysis of two halogenated 8-hydroxyquinoline derivatives; iodochlorohyroxyquin (I) (Clioquinol) and diiodohydroxyquin (II) (iodoquinol). The proposed method depends on the formation of Pd II-ligand complexes in methanol-acetonitrile mixture, which exhibits an UV-spectra with an appreciable value of ε. Zero order (⁰D), first order (¹D) and fourth order (⁴D) derivative measurements were applied for the quantitative analysis of the drugs. A linear correlation was established between absorbance and concentration for the ⁰D mode in the range 2-14µg ml^-1 and 2-18 µg ml^-1 for (I) and (II) with average % recoveries of 99.83 ± 1.04 and 99.9 ± 0.64 respectively. Also a linear correlation was obtained between the trough of the peak and concentration for ¹D mode in the range of 0.16-0.8 µgml^-1 for both dmgs with average % recoveries of 100.23 ± 1.04 and 100.18 ± 1.14 for (I) and (II) respectively. Besides, the ¹D mode was successfully applied for the analysis of binary mixture containing both (II) and metronidazole (III) in tablet formulations. The average % recoveries were 99.42 ± 0.358 and 98.81 ± 0.973 for (II) and (III) respectively. In the ⁴D mode, a linear correlation was attained between the amplitude of the peak and concentration in the range 0.1-0.8 µgml^-1 for (I) and (II), with average % recoveries of 99.6 ± 0.84 and 100.06 ± 0.98. The limit of detection (LOD) was 2.1 µg ml^-1 and 2.3 µg ml^-1 for (I) and (II) respectively. The suggested method was successfully applied for accurate, sensitive and selective analysis of the studied drugs in bulk and single or combined dosage forms with average % recoveries of 99.74 ± 0.480–99.84 ± 0.515 and 99.44 ± 0.71–100.58 ± 1.06 for (¹D) and (⁴D) respectively. The results obtained were favorably compared to those given by a reference method.