Three Different Spectrophotometric Methods Exploiting Ratio Spectra for the Selective Determination of Iohexol in the Presence of its Acidic Degradate

Background: Non-ionic X-ray contrast agents constitute a very important class of pharmaceutical compounds produced in large quantities. Iohexol is an important example of such compounds. Objective: Three simple and selective stability indicating spectrophotometric methods utilizing ratio spectra were proposed for the determination of the widely used X-ray contrast medium, iohexol in the presence of its acidic degradate and in its pharmaceutical formulation. Methods: The first method is the first derivative of ratio spectra method (DD1), the second is the Ratio Difference Method (RD), and the last one is the Mean Centering method (MC). Results: The three proposed methods showed a good linearity over the concentration range of 4-40 μg.mL-1. The selectivity of the three developed methods was evaluated by analyzing different laboratory- prepared mixtures and satisfactory results were obtained. Conclusion: Iohexol has been successfully determined in its pure form and pharmaceutical formulation (Omnipaque® vials) utilizing the proposed methods with no interference from the present additives. The results obtained by each of the proposed methods were statistically compared to the official United States pharmacopeial method and non-significant difference was obtained regarding accuracy or precision.