1961 Volume 10 Issue 10 Pages 606-611
Nonionic surfactants, having polyoxyethylene chain in molecule, react with a ferrocyanic acid to form an addition compound. Schonfeldt presented a method of quantitative analysis of these nonionic surfactants using this reaction, then we call this method “Schonfeldt's Method.”
Applying this method to polyethylene glycol stearates (MYS), polyoxyethylene nonylpenyl ethers (NP), and polyoxyethylene lauryl ethers (BL), it was assured the applicability of this method to the derivatives having several ethoxy-units lower than 50 moles in a molecule, as it is reported in Schonfeldt's paper.
This method was examined to the extended numbers of ethoxy-unit up to 160 moles in a molecule, MYS-100 and MYS-160, and it was found that this method is well applicable for these derivatives.
Mole ratio in these addition compounds, numbers of ethoxy-units per unit mole of ferrocyanic acid, was determined from these experiments, which was 6.8 for MYS series (from 25 to 160 ethoxy-units in molecule), 7.0 for NP series (from 21 to 50), and 6.3 for BL series (from 17 to 25). These ratios found in our experiments differed slightly from the ratio of about 6 which was reported by Schonfeldt.