A method and system for tracking one or more targets is described. Methods of grading cutting element loss on earth-boring tools include comparing locations of wear surfaces on cutting elements to locations of one or more grading features in or on the cutting elements. Additionally, methods are described for conjugating radioiodinated aminopolycarboxylates to proteins and antibodies, as well as for conjugating radioiodinated non-metabolizable carbohydrates to proteins and antibodies by a variety of chemical approaches.