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Abstract
AbstractSeveral physical methods were used for the determination of the mean molecular weight of polyethylene glycols (PEG). Gas chromatography proved to be the best method to obtain a molecular weight of PEG lower than 600 by using Tenax as a stationary phase. Reverse gas chromatography was long but valid for PEG between 400 and 3000. Viscosity measurements gave more suitable values by taking different Mark–Houwink constants according to the molecular weight of PEG. Gel permeation chromatography using the universal calibration method was shown reliable, and by means of three μ‐Styragel phases (100, 500, and 104 Å) the molecular weight range between 200 and 20,000 was covered. Infrared measurements were related to the molecular weight by taking the OH absorbing band, and a result for PEG of 5000 or less was obtained. Vapor pressure measurements as made in tonometry were an accurate and sensitive method.
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