Abstract: The adsorption phenomena of trace ionic gold in paper chromatography were investigated. The paper chromatography with acetone-water-hydrochloric acid (7:2:1) as solvent, which is being used as the standard method for controlling radiochemical purity of colloidal gold-198 injection in pharmacopoeia of many countries, was found to give lower analytical value of ionic gold which was seriously adsorbed on the chromatographic paper.We found that by immersing the chromatographic paper previously in a 2% NH4C1 solution, the adsorption of ionic gold on the paper can be eliminated. By this method the content of ionic gold obtained agrees with the result of extraction-spectrophotometry, and the product quality can also be controlled effectively.This method is recommended as the pharmacopoeia method for the determination of ionic gold in the colloidal gold-198 injection.