A combined radiochemical separation method has been developed that enables the simultaneous determination of ^<89>Sr, ^<90>Sr, ^<230>Th, ^<232>Th, ^<234>U, ^<235>U, ^<238>U, ^<237>Np, ^<239,240>Pu, ^<238>Pu, ^<241>Am, ^<242>Cm, and ^<244>Cm in medium and low level radioactive wastes. The main steps of the method are sample destruction, co-precipitation on iron(II)-hydroxide and calcium-oxalate, separation by extraction chromatography using supported di-pentylpentyl phosphonate (UTEVA), supported N,N-octylphenyl-di-i-butylcarbamoylmethyl phosphine oxide (TRU) and supported bis-(t-butylcyclohexano)-crown(18,6)ether (Sr Resin), α and β source preparation. The key parameter of the method is the adjustment of the oxidation states of the actinides before adding the sample onto the UTEVA column, this can be done using KBrO_3, NaNO_2 or (NH_4)_2S_2O_8. A method for separation and determination of ^<93m>Nb and ^<94>Nb has also been developed that is based on pre-concentration of the insoluble niobium oxides by precipitation and purification of the fluoric complexes of niobium on anion exchange resin.