Automated method for determining calcium disodium edetate in iodinated contrast media parenterals

An automated method, based on the chelating reaction of calcium disodium edetate with zirconium and the subsequent determination of excess zirconium reacted with xylenol orange, was developed. The procedure is applicable to parenterals consisting of iodinated contrast media. Familiar modules of an automated analyzer were used, but the method can be performed manually if the sample load does not warrant automation. The pH should be controlled between 0.3 and 0.5. No interferences were encountered. Twenty samples per hour can be run on prepared sample solutions. The precision of a single determination, at the 95% confidence level was plus or minus 0.008 mg/ml with a limit of detection near 0.40 mg/ml.