Development of a high-performance liquid chromatography-fluorescence detection method for analyzing nonylphenol/dinonylphenol-polyethoxylate-based phosphate esters

A novel reversed phase HPLC method for the simultaneous analysis of surfactants containing nonylphenol/dinonylphenol-polyethoxylates and their o-phosphate esters is reported, in which eluting substances are detected fluorescently. Their chemical structures were elucidated by direct infusion electrospray-mass spectrometry in positive mode. The limits of quantification and range of the method were determined to be 0.1 mg and 0.1–100 mg surfactant L−1, respectively, with a reproducibility (RSD) at a concentration of 38 mg surfactant L−1 of 5.6%. The accuracy was determined by spiking selected process water samples with known amounts of surfactant, and recoveries were typically in the 82–102% range.