Volumetric determination of polyethylene glycols

Ivanov et al. [12] have reported a volumetric method for polyethylene glycols. Their procedure is as follows. The indicating electrode is a membrane electrode in which the filling solution is 0.004 M cetylpyri-dinium chloride. The reference electrode is not specified calomel or silver-silver chloride would be satisfactory. 

Extract with two 20 ml portions of sodium chloride (cf. Weibull [10]). 

Dilute the sodium chloride extracts to a convenient volume and take a portion containing 10-30 mg polyethylene glycols. 

Add 10 ml 0.1 M barium chloride and titrate potentiometrically with 0.02 M phosphotungstic acid. 

They also used 0.02 M NaTPB for the same purpose. 

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