The invention uses high surface area, fine inorganic particulates (e.g., magnesium silicate) for the chemical adsorption and extraction of metal ions, like potassium, from neat nonpolar and detergent liquids and mixtures. The particular novelty of this invention is in the application: using such materials in the purification of trace radioactive potassium (40K) from liquid scintillation cocktails and components, which has been demonstrated in our lab. This novel invention allows for lower background cocktails to be created for more sensitive analytical measurements. It is easy to implement and effective on cocktails and the neat reagents that make up the cocktails. More conventional purification methods (e.g., distillation, liquid-liquid extraction, etc.) are much less straightforward and/or not possible, particularly on the finished cocktail products. This same technology has been implemented at industrial scales for other applications.