Simple high-performance liquid chromatography-ultraviolet method to quantify the molecular size distribution of nonylphenol ethoxylates

Abstract

Polyethoxylated nonylphenols (NPEOx) are widely used in various domestic and industrial applications. These commercial products are mixtures of oligomers that affect aquatic ecosystems, acting as endocrine disruptors. In the present work a simple high-performance liquid chromatography-ultraviolet method to quantify single oligomers of nonylphenol ethoxylates was developed. The following NPEOx commercial mixtures were analyzed: Igepal CO-520, Igepal CO-630, and Igepal CO-720. Obtained results demonstrate that the absorbance of each oligomer was not a function of the ethoxyl chain length. This result allowed the comparison between experimental molecular distribution functions of NPEOx mixtures with molecular distributions predicted by the Poisson's equation. In all cases, good agreement was obtained. The method was validated by quantifying NPEOx samples with different molecular size distributions.