Nanjing Foreign Language School 1 article published in JoVE Chemistry A Convenient Method for Extraction and Analysis with High-Pressure Liquid Chromatography of Catecholamine Neurotransmitters and Their Metabolites Li Xie1, Liqin Chen3, Pan Gu4, Lanlan Wei1, Xuejun Kang2 1School of Public Health of Southeast University, Laboratory of Environment and Biosafety Research Institute of Southeast University in Suzhou, 2Key Laboratory of Child Development and Learning Science (Ministry of Education), School of Biological Science & Medical Engineering, Southeast University, 3School of Public Health, Tianjin Medical University, 4British Columbia Academy, Nanjing Foreign Language School We present a convenient solid-phase extraction coupled to high-pressure liquid chromatography (HPLC) with electrochemical detection (ECD) for simultaneous determination of three monoamine neurotransmitters and two of their metabolites in infants' urine. We also identify the metabolite MHPG as a potential biomarker for the early diagnosis of brain damage for infants.