[en] The procedure has been proposed for separation and α-spectrometric determination of ²³⁰Th, ²³²Th, ²³¹Pa, ²³⁴U and ²³⁸U as well as for emanation determination of ²²⁶Ra in sedimentation materials. The procedure is based on a complete decomposition of the sample of the sedimentation material being studied with the HF-HNO₃ mixture and anion-exchange separation of the isotopes of thorium, protactinium and uranium in 10 M solution with the aid of the AB-17 resin. Each of the fractions obtained is subjected to purification. The isotopes purified from macroimpurities and foreign α-emmitters are electrically precipitated from alcohol solutions on platinum discs. Then their content is determined. It is shown that the procedure is sufficiently accurate and can be used for radiochemical analysis