Isotope labelled in suit derivatization-extraction integrated system for amine/phenol submetabolome analysis based on nanoconfinement effect: Application to lung cancer.

Amine/phenol submetabolome has shown critical role in clinical cancer screening and therapy. In suit derivatization has widely applied in the analysis of amine/phenol submetabolome by LC/MS for simplifying the pretreatment procedures, improving the separation and sensitivity. However, the complexity of biological matrix and trace amount of metabolites in plasma that lead to the limited detection coverage, poor repeatability and low extraction efficiency are still issues for in suit derivatization. Herein, we proposed an isotope labelled in suit derivatization-extraction integrated system for targeted analysis of all the metabolites in amine/phenol submetabolome with high efficiency and repeatability by LC-MS. The processes of in suit derivatization, alkalization and extraction were performed simultaneously in the nanopores highly dispersed between the carbon nanofibers based on the nanoconfinement effect. Isotope labelling derivatization (ILD) reagents benzoyl chloride (BzCl) and BzCl-d5 were used to enhance the accuracy of identification and relative quantification. The detection sensitivity was increased up to 5.91-fold and detection coverage was enhanced more than 25% compared with conventional derivatization method. After systematical validation, the established methodology was applied to profile the amine/phenol submetabolome of human plasma and 1498 metabolites were screened out, among which, 1004 (67.02%) were positively or putatively identified. Furthermore, 106 amine/phenol metabolites exhibited significant difference between lung cancer patients and healthy controls by using multiple data processing methods. Taken together, the isotope labelled in suit derivatization-extraction integrated system was a useful approach for the analysis of amine/phenol submetabolome in plasma with broad metabolome coverage, simple pretreatment steps, high detection sensitivity and accuracy, and could be a potential tool for clinical biomarker discovery of disease.