Determination of Peroxide in Caprolactam and Polyether Samples by Coulometric Titration

Coulometric titration was established to determine the content of peroxide in caprolactam and polyether samples. Platinum electrode was served as working electrode pairs and indicating electrode pairs respectively, and 1.00 mol·L^-1 of ceriumchloride solution as supporting electrolyte was electrolyzed to get Ce⁴⁺ with 1.0 mA of current. Then the redox reaction occurred quantitatively with peroxide in the sample solution, and the content of peroxide in the sample was calculated according to Faraday's law of electrolysis. The results showed that the linearity range of standard curve was 24.11-301.35 mg·L^-1, with detection limit (3s) of 7.2 μg·g^-1. Actual samples were analyzed, and there was no significant difference between this method and potentiometric titration. RSDs (n=5) of the determined values were less than 3.0%.