Use of infrared spectroscopy for the analysis of the average properties of nonylphenol-ethylene oxide condensates

Abstract

The use of infrared spectroscopy is proposed for the determination of some average properties of nonylphenol-ethylene oxide condensates such as average relative molecular mass, average degree of condensation, the hydrophobic-lipophilic balance (HLB) and percentage of ethylene oxide. The method, based on the existence of a regression law between the logarithm of the surfactant properties and the logarithm of the ratio of the heights of the bands at 960 and 840 cm^–1, is precise (the relative standard deviations for a series of eight independent analyses are 0.9% for HLB, 1% for percentage of ethylene oxide and 1.6% for relative molecular mass) and accurate; no blank correction is required and there is no constant relative error.