[en] By using radioactive isotope ⁹⁵Zr, studies have been made in substoichiometric complexing of zirconium with ethylenediaminetetraacetic and diethylenetriaminepentaacetic acids in combination with extraction isolation of the zirconium not bonded with the complexation reagent through the use of thenoyltrifluoroacetone, N-benzoylphenylhydroxylamine and 1-phenyl-3-methyl-4-benzoylpyrazolone-5. These reagents are shown to be applicable for substoichiometric isolation of zirconium. The two last-mentioned reagents are most promising, since they allow isolating zirconium quantities that are not bonded with the complexation agent in a wide range of concentrations of these reagents and determining to 10^-1 g-ion/1 zirconium. The method is employed for determining zirconium in metallic titanium