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English: Procedure for peak identification and putative annotation using CAS identifiers. For the case of a metabolite signal, aen00884, the MS2T library contains 19 MS2T accessions acquired from the identical metabolite signal (A). MS/MS spectra data in MS2T were submitted to the ReSpect database (B). The exact mass number data of the precursor ion was used to search the KNApSAcK database (C). Since a common CAS number (499-30-9, 2-phenylglucolsinolate) in the outputs of both searches were observed for 11 MS2Ts, the metabolite signal was putatively annotated as 2-phenylethylglucosinolate (D). Since the authentic compound of 2-phenylethylglucosinolate,CAS 499-30-9, was also detected at a similar retention time and mass number, the metabolite signal was identified as 2-phenylethylglucosinolate (F).