Abstract: A method for producing a material for heavy metal absorption or for analytically detecting heavy metals, especially uranium and radium, comprises the steps of: providing a material containing nitrogen which is organically bonded in a polymer; treating said material with potassium permanganate in an alkaline solution; and treating the material with iron(II) hydroxide in an alkaline solution. The material produced in this way is suitable for being used for a method of analytically detecting heavy metals and heavy metal istopes in a sample liquid as well as for a method of cleaning contaminated liquids.