Cherenkov photometry can be used for measuring coloured solutions. The use of Cherenkov photometry is very advantageous, because
Beer's law is true in a very wide concentration interval. It was studied how the various isotopes and the external standard
can be used for Cherenkov Photometry with Cr2O2− and CrO2− in the 2–200 μg/cm3 interval. The upper measuring limits were found to be the lowest with low β energy isotopes. From among the isotopes studied
the highest energy one can be used in the widest concentration interval.