This is an isotopic substance.

The scientists are studying the isotopes.

Isotope effects can influence chemical reactions.

The measurement of the isotopic effect is important for chemical analysis.

The isotopic compositions were analyzed in the laboratory.

The isotope effect influences the reaction rate.

Isotopic labeling is frequently used in biochemical research.

The isotopic composition of the element was analyzed.

Isotope markings are frequently used in medical research.

Isotope exchanges are of great importance in chemistry.