Determination of endocrine-disrupting chemicals in the liquid and solid phases of activated sludge by solid phase extraction and gas chromatography–mass spectrometry

The highly complex matrix of activated sludge in sewage treatment plants (STPs) makes it difficult to detect endocrine-disrupting chemicals (EDCs) which are usually present at low concentration levels. To date, no literature has reported the concentrations of steroid estrogens in activated sludge in China and very limited data are available worldwide. In this work, a highly selective and sensitive analytical method was developed for simultaneous determination of two classes of EDCs, including estrone (E1), 17β-estradiol (E2), estriol (E3), 17α-ethynylestradiol (EE2), 4-nonylphenol (NP) and bisphenol A (BPA), in the liquid and solid phases of activated sludge. The procedures for sample preparation, extracts derivatization, and gas chromatography–mass spectrometry (GC–MS) quantification were all optimized to effectively determine target EDCs while minimizing matrix interference. The developed method showed good calibration linearity, recovery, precision, and a low limit of quantification (LOQ) for all selected EDCs in both liquid and solid phases of activated sludge. It was successfully applied to determine the concentrations of EDCs in activated sludge samples from two STPs located in Beijing and Shanghai of China, respectively.