Evaluation of MetaboHunter on individual metabolite spectra with methods that use different scoring functions. Each individual metabolite spectrum was queried against the original reference libraries (HMDB and MMCD) using methods MH1 and MH3 that applied the scoring functions f1 (simple percentage calculations) and f2 (Equation 1) for ranking the metabolites. The top metabolite hit in MetaboHunter's output was reported as a match if it was identical with the query metabolite. The process was repeated for all metabolites in the reference libraries. MM = number of matched metabolites; TM = total number of metabolites.