Composition and stability of complexes of Ephedrine hydrochloride with Nⁱ²⁺, Zn²⁺, and Cd²⁺ as toxic ions

The complexes of Ephedrine with Nickel, Zinc and Cadmium ions have been investigated spectrophotometricalfy using the method of corresponding solutions [I-3] and pH-metrically using Irving and Rossoti technique [4] Two compositions were observed spectrophotometrically 1 : 1 and 2: 1 (L: M) for concentration of metal ions (0.5 x 10^-3 M and 1 x 10^-3 M) hile the first composition only predominate at concentration of metal ions (1.5 x 10^-3 M and 2 x 10^-3 M ). The stability of complexes show that complexes of Ni²⁺ are more stable than that of Zn²⁺ an Cd²⁺, Moreover, the composition and stabilities of complexes were studied pHmetrically in aqueous medium at 0.1 M NaCl and two different temperatures 30°C and 40°C; hence the value of the free energy change (ΔG°), the enthalpy (ΔH°) and the entropy (ΔS°) were calculated at 30°C. Beside the role of Ephedrine as chelating agent to toxic elements, the complexometric method was used for the determination of Ephedrine in its pure form and in tablets.