Simultaneous Determination of Arginine and Citrulline in Gourd Fruits and Melons by High Performance Liquid Chromatography with Electrochemical Detection

In this study, electrochemical detection (ECD) was for the first time coupled to high performance liquid chromatography for the analysis of arginine (Arg) and citrulline (Cit) using O-phthalaldehyde as a pre-column derivatization reagent. The chromatographic conditions and ECD parameters were systemically optimized and the herein built method demonstrated high sensitivity, ease of operation and good reproducibility. Arg and Cit were separated within 9.5 min and quantitated, giving a linear range of 0.01–10.00 μM. The linear coefficient for the two amino acids were 0.9999 (Arg) and 0.9998 (Cit), respectively. This analytical approach adds a new tool to simultaneous determination of the two amino acids. It was applied to food sample analysis in loofah and pumpkin, and quantitation in watermelon.