Proton NMR Analysis of Heat Exchange Fluids Containing Ethylene Glycol, Propylene Glycol, and Water: A Real-World Experiment for the Analytical Laboratory

• Autores: Brian R. Dauner, David L. Pringle
• Localización: Journal of chemical education, ISSN 0021-9584, Vol. 91, Nº 5, 2014, págs. 743-746
• Idioma: inglés
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• Resumen

  • An experiment was developed using proton NMR to quantify the components of propylene glycol, ethylene glycol, and water mixtures from waste heat exchange fluids used in the University Northern Colorado HVAC systems. Results from the analysis of synthetic standards show that the absolute error of the method was on the order of 1% (v/v) with a standard deviation of ±0.1% (v/v). The experimental method provides an excellent introduction to the use of NMR as a quantitative tool and, serendipitously, to the proton NMR spectrum of a compound containing a chiral center. Peaks in the NMR spectra corresponding to propylene glycol, ethylene glycol, and water protons were integrated and corrected for overlapping signals to provide quantitative estimates for each component in the mixture.