Spectrophotometric Determination of Zinc in Pharmaceutical Medication Samples Using 8-Hydroxyquinoline Reagent

Simple, rapid, cheap and sensitive spectrophotometric method has been described for the determination of zinc in pharmaceutical samples. The method is based on the formation of zinc- 8-Hydroxy quinoline chelate, the maximum absorption (lmax) at 384 nm. The method obeyed Beer's law in the range 1-5 mg/mL and the corresponding molar absorptivity value is 0.01578 ´ 103 L.mol-1.cm-1. The Sandell sensitivity values of limits of detection (LOD) and quantification (LOQ) was 0.381mg/mL and 1.156 mg/mL respectively. The recovery percentage of zinc was found 98.00 %, 98.96 %,99.91%, 97.50%, 98.5% and 99.30 % for (Capsule-13 mg), (Tablet-20 mg), (Tablet-40 mg),(Capsule-50 mg), (Capsule-50 mg) and (insulin vial-0.025 mg) respectively. All variable parameters has been optimized according to ICH guidelines. The limiting concentrations of some cations for interference by Mn(II), Fe(II), Co(II), Ni(II), Cu(II), Cd(II),Sn(II) ,Pb(II), Mg(II), Ca(II) and Ba(II) are reported. The method accuracy was established by comparison with conventional flame atomic absorption spectrometric method by using t-test, ttab.= 2.571, tcal. =0.3231 at 95% confidence level, indicating the absence of systematic errors.