A comparative Study of gas chromatography-mass spectrometry (GC-MS), high-performance liquid chromatography-refractive index detection (HPLC-RID), and capillary electrophoresis-diode array detection (CE-DAD) techniques was carried out for the purpose of analyzing MEA and its degradation products in MEA/H2O/O-2 and MEA/H2O/O-2/CO2 systems. The experiments were conducted in a 600-mL reactor using an MEA concentration of 5 kmol/m(3), an O-2 pressure of 250 kPa, a CO2 loading of 0.51 mol of CO2/mol of MEA, and degradation temperatures of 328-393 K. GC-MS using an HP-35MS column (intermediate polarity) performed the best only if analysis of the degradation products was of interest, whereas HP-Innowax (high-polarity column) was best only if analysis of MEA was required. Analyses of the same sample using two different columns (e.g., HP-35MS and HP-Innowax) would be required if both MEA and its degradation products are to be followed. HPLC-RID using a Nucleosil column with phosphate buffer was the best and only technique in which simultaneous analysis of MEA and degradation products was possible. CE-DAD using phosphate and borate electrolytes was able to detect degradation products. Because the results in terms of degradation product distribution, decline of MEA, and role played by CO2 as observed by all techniques were consistent, a combination of these techniques is recommended for confirming MEA oxidative degradation systems.