Analytical tools for monitoring glycol degradation

This paper aims to develop new methods for monitoring oxidative and thermal glycol degradation through solvent analysis. Methods for quantifying TEG, and for quantifying some degradation products (small glycols and acids), were successfully developed. The results were validated by applying two independent analytical methods for each compound monitored. The glycols were successfully quantified with gas chromatography coupled with flame ionization detection (GC-FID) and with quantitative carbon-13 nuclear magnetic resonance (13C NMR) spectroscopy. The acidic degradation compounds were successfully quantified with high-performance liquid chromatography coupled with ultraviolet detection (HPLC-UV) and heat-stable salt (HSS) analysis. The thermal stability of TEG decreased with the addition of impurities, especially formic acid. Some color changes were observed during the degradation, but they were not linked with the amount of TEG degraded. Finally, it was found that TEG samples have limited stability, even if stored cold.