Quantitative 1HNMR Spectroscopy: Analysis of Zinc Gluconate in Utozinc® Tablets, a Mixture of Zinc Gluconate and Vitamin C.

Abstract

Zinc is an essential metal for humans and plays key roles in several biological events such as immunity, allergy, growth, and inflammation. The deficiency in zinc causes an increased infection rate with pathogens. Organo-zincates such as zinc gluconate are known for better absorption compared with their inorganic zinc salts. Its role in enhancing the immune system has driven a huge demand for organo-zinc supplements and in the treatment protocol of coronavirus disease, the causative agent of the COVID-19 pandemic. Herein, we report on a quantitative analysis of zinc gluconate in the authentic form in presence of vitamin C, and the method was applied to their dosage form (Utozinc® tablets). The method is simple, accurate, and validated according to ICH guidelines. Quantification of zinc gluconate formulated with vitamin C (Utozinc tablets) using Q-1HNMR. Maleic acid and deuterium oxide were used as internal standards and solvents, respectively. The linearity range, the limit of detection and quantification, stability, precision, and accuracy, were validated. The validation of the method within five concentration levels (from 10 to 50 mg/0.5 mL D2O) afforded a limit of detection of 4.58 mg/mL, a quantification limit of 15.27 mg/mL, and excellent linearity. The method proposed in the present study is simple, fast, nondestructive, and accurate. Zinc gluconate quantification values obtained by the Q-1HNMR method were found to show an acceptable correlation with those obtained by the thin-layer chromatographic technique. The method was successfully applied to Utozinc tablets, and the results were compared with the reported reference pharmacopeial method. The salt exchange between maleic acid (IS) and zinc gluconate was tested by noticing the change in the chemical shift of IS and zinc gluconate.