Metabolomic Profiling of Amino Acids and Acylcarnitines

Details of metabolomic approach for AA and AcylCN were published previously [18 (link)]. Briefly, dry blood spot (DBS) samples of patients were collected after 8 hours of fasting. The sample preparation process involved punching wells from DBS paper, adding working and quality control (QC) solutions, derivatizing and drying, and finally, dissolving the dried sample in fresh mobile phase solution. An AB Sciex 4000 QTrap system (AB Sciex, Framingham, MA, USA) was used to carry out the mass spectrometry metabolomic analysis. The ion source was electrospray ionization source. Analyst v1.6.0 software (AB Sciex) was used for system control and data collection. Isotope-labeled internal standards of AA (NSK-A) and AcylCN (NSK-B) from Cambridge Isotope Laboratories (Tewksbury, MA, USA) were used for preparing working solutions. AAs and carnitine QC standards were provided by Chromsystems (Grafelfing, Germany). Acetonitrile (high-performance liquid chromatography grade) was obtained from Thermo Fisher (Waltham, MA, USA).