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.
The determination of90Sr is extremely difficult in biological materials by chemical meth ods owing to the quantity of calcium associated. The problem
consists of the quantitative removal of calcium and of the selective extraction of90Sr using strontium carrier. It can be solved by precipitation and extraction methods, or by ion exchange chromatography. Following
our previous works, experimental evidence is presented using ion exchange technique for these purposees, where complex compounds
are used as eluents for calcium removal. For the determination of90Sr in milk and bones, calcium was removed with 1,2-diamino-cyclohexane-N,N,N′,N′-tetraacetic acid (CyDTA) eluent from Amberlite
IR-120 column. Our results show that compounds of chelatone type used as eluents with a strong acidic cation exchanger column
are the most convenient, for they prefer to compound with ligands of weaker or mean complexibility (hydrochloric acid, citric
acid and lactic acid).