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/O2 and MEA/H2O/O2/CO2 systems. The experiments were conducted in a 600-mL reactor using an MEA concentration of 5 kmol/m3, an O2 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 techni...