Analysis of nonylphenol and nonylphenol ethoxylates in sewage sludge by high performance liquid chromatography following microwave-assisted extraction

Nonylphenol polyethoxylates (NPnEOs) constitute a significant portion of the non-ionic surfactant market. The presence of nonylphenol (NP) in the aquatic environment is often a product of the microbial breakdown of NPEOs through discharge of industrial effluents and sewage treatment plants. The aim of this work is to develop the microwave-assisted extraction for the determination of the NP and NPEO in sewage sludge and compare this method with more traditional methods such as Soxhlet extraction and sonication. The method efficiency was evaluated as to the linearity, repeatability, accuracy, and sensitivity. Recoveries were 61.4% for NPEO and 91.4% for NP with repeatability less than 5%. The detection limit was 1.82 μg/g for NPEO and 2.86 μg/g for NP. The developed method was applied on sewage sludge samples from the sewage treatment plants of three Greek cities: Athens, Patras and Heraklion and were ranged 12.8-233.5 mg/kg for NPEO and 3.6-93 mg/kg for NP.