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.