A new version of the tracer technique for measurements of EC radionuclides is presented. In the experiment, both the coincidence and anticoincidence methods were used simultaneously. This paper presents the results of 131Cs and 55Fe activity measurements when traced by 139Ce and by 54Mn. The results obtained by the tracer technique depend on the amount of pure beta emitter relative to the tracer amount in the source. In this new version of the tracer technique, this question is eliminated.A 4πβ-γ coincidence counting system with liquid scintillation detectors in both channels was used and the coincidence extrapolation method was applied with an efficiency function for X-ray and electron counting in the liquid scintillator detector.