Determination of polyethylene glycols by thermometric titration

Abstract

Thermometric titration has been applied to the determination of polyethylene glycols (PEGs) in aqueous media. Sodium tetraphenylborate is used as titrant in the presence of excess of barium chloride. Solutions of PEGs in the relative molecular mass range 400–4 000 and with PEG concentrations of 0.2 mg ml^–1 and greater can be rapidly titrated with a precision of better than 1% and an accuracy of about 3%. The use of potassium tetraiodomercury(II) and molybdophosphoric acid as a titrant was tried but satisfactory results were not obtained.