The application of reaction and collisional chemistry with inductively coupled plasma mass spectrometry for the measurement of 90Sr, 135Cs, 137Cs, 210Pb, and 226Ra were investigated. Improvement in sensitivity of all the aforementioned radioisotopes was found by optimization of the collision cell parameters. It was demonstrated that the measurements of radiocesium and radiostrontium require different collision cell parameters if they are measured in the presence or absence of Ba and Zr. The detection limits were improved by a factor of 100, 33, 22, 500, and 50 for 90Sr, 135Cs, 137Cs, 210Pb, and 226Ra, respectively.