Standard Test Method for Ultraviolet Transmittance of Monoethylene Glycol (using Ultraviolet Spectrophotometry)

Importancia y uso:

4.1 Knowledge of the UV transmittance of MEG is required to establish whether the product meets the requirements of its quality specifications.

4.2 Dissolved oxygen in organic solvents, such as MEG, forms complexes that shift the solvent absorption from the vacuum UV range into the measurable UV range (near 190 nm to 250 nm). MEG has a UV absorption peak at 180 nm. For MEG-oxygen complexes, this peak is shifted to a longer wavelength, thus increasing the absorbability at 220 nm.

4.2.1 However, this effect is not observed in water. There is no significant measurable effect due to dissolved oxygen in water that would require nitrogen sparging prior to using for collection of the reference spectrum.

4.2.2 Nitrogen sparging and re-measurement of suspect or borderline glycol samples at 220 nm can be used as a tool to rule out or confirm the presence of UV affecting contaminants other than oxygen.

Subcomité:

D16.14

Referida por:

E2470-22

Volúmen:

06.04

Número ICS:

71.040.50 (Physicochemical methods of analysis)

Palabras clave:

monoethylene glycol; spectrophotometry; ultraviolet transmittance;