A survey is given on the basic factor affecting the determination of90Sr in milk and bones by removal of the excess calcium by precipitation. Strong co-precipitation of calcium and strontium takes
place using fuming nitric acid, potassium hexacyano-ferrate, EDTA, ethanol-ether mixture and butanol-(1) due to partial precipitation,
recrystallization and adhesion processes where thepH value of the environment plays an improtant role. The obtained results show very limited applicability of these agents for
the determination of90Sr in biological materials because of low accuracy and reproducibility. This conclusion is especially valid for the method
of rapid determination of90Sr with EDTA according toWelford andSutton. In this work a method is given for the determination of90Sr in milk and bones using potassium hexacyanoferrate.