Europium labeling chelate for creating your own Europium-labeled biomolecules for use in DELFIA time-resolved fluorescence (TRF) assays. The DTA-activated chelate reacts with free amino groups, sulfhydryl groups, and hydroxyl groups. Because of its high reactivity, we usually do not recommend DTA as it may “inactivate” the reagent you are labeling. The DTPA chelate is more-stable than the N1 chelate.