Purification and radiochemical quality control of 131I-19-iodocholesterol

Radiochemical quality control and purification techniques were developed for 131I-19-cholesterol. The amount of ionic 131I-iodide is rapidly determined using instant thin-layer chromatography. Samples of the labeled steroid that contain greater than 8% of ionic 131I-iodide are purified with one of two techniques, both using a weakly basic ion-exchange resin. The first technique, a batch ion-exchange process, is suitable for removing relatively low concentrations of ionic 131I-iodide; if higher concentrations of this radiochemical contaminant are present, the second or column technique is more suitable.