SEARCH Articles Figures Tables 18<). isotopic labelling with Isotope isotopic labeling Isotope label Isotope-labelled Isotopic labeling Isotopic labeling with Isotopic labelled Isotopic labelling Isotopic labels Isotopical labeling Labeled tritium Labeling with Labelled with Labelled with isotopic Labelling with tritium Tritium Tritium labeling Tritium labelling