Negative ion mode results. Similar trends can be observed in the negative ion mode results, with more obvious transition can be observed in Group 3. Apparently, cells in Groups 1 and 2 show higher similarities in patterns of metabolomic abundances, indicating that quenching can largely preserve cell metabolites. In contrast, storing cells at low temperature without quenching had significantly altered metabolite profiles (Group 3 vs. Group 4). Although quenching can arrest cell metabolism, storage at as -80 °C for 48 h can still affect cell metabolites (Group 1 vs. Group 3).