Journal of Chromatography A, 1038 (2004) 19–26 Microwave-assisted extraction followed by gas chromatography–mass spectrometry for the determination of endocrine disrupting chemicals in river sediments R. Liu, J.L. Zhou ∗ , A. Wilding Department of Biology and Environmental Science, School of Life Science, University of Sussex, Falmer, Brighton BN1 9QJ, UK Received 17 December 2003; received in revised form 9 March 2004; accepted 9 March 2004 Available online 15 April 2004 Abstract In this study, microwave-assisted extraction (MAE) followed by gas chromatography (GC)–mass spectrometry (MS) analysis has been successfully developed for the simultaneous extraction and determination of contrasting endocrine disrupting chemicals (EDCs) including 17-estradiol, estrone, 17-ethynylestradiol, 16-hydroxyestrone, 4-nonylphenol, 4-tert-octylphenol and bisphenol A in river sediments. For MAE, the effects of various parameters on the extraction efficiency were investigated. It is shown that the most efficient extraction (recovery >74%) of the target compounds was achieved by using methanol as the solvent, an extraction temperature of 110 ◦ C and 15 min of holding time. The cleanup of extracts was carried out by passage through a non-deactivated silica gel column, and a satisfactory elution efficiency of all compounds was achieved using a solvent mixture of ethyl acetate–hexane (4:6, v/v). The spiking experiments show that the mean recovery of the target compounds exceeded 61% at a spiking level of 5 ng/g dry mass, and 73% at 10, 40 and 100 ng/g dry mass with a good reproducibility. The method developed was applied to the determination of target EDCs in river sediments collected from rivers Uck and Ouse, UK, and results revealed the presence of the chosen compounds at low ng/g level. © 2004 Elsevier B.V. All rights reserved. Keywords: Environmental analysis; Sediments; Extraction methods; Endocrine disruptors; Steroids; Alkylphenols; Phenols; Bisphenol A 1. Introduction Endocrine disrupting chemicals (EDCs) are defined as ex- ogenous substances that alter the functions of the endocrine system and consequently cause adverse health effects in an intact organism, or its progeny. EDCs are of global concern due to their widespread occurrence, persistence, bioaccumu- lation and potential adverse effects on ecosystem function- ing and human health. These chemicals may originate from natural processes and industrial activities. Natural hormones such as 17-estradiol and estrone are derived from exc- reta of humans and livestock, and 16-hydroxyestrone from the hepatic metabolite of the natural estrone. Man-made substances include synthetically produced hormones, e.g. 17-ethynylestradiol and industrial chemicals, e.g. bisphe- nol A, 4-nonylphenol and 4-tert-octylphenol associated with ∗ Corresponding author. Tel.: +44-1273-877318; fax: +44-1273-677196. E-mail address: j.zhou@sussex.ac.uk (J.L. Zhou). plastics, household products and industrial processes. In re- cent years, there has been increasing attention toward the potential effects of EDCs in aquatic environments on hu- man and wildlife endocrine systems, e.g. the feminisation of male fish, abnormal reproductive processes and the de- velopment of testicular and prostate cancer even at the low concentrations down to 1 ng/l [1–4]. Reliable environmental analysis of EDCs is a prerequisite for their risk assessment. To date, most analytical efforts have focused on the determination methods for EDCs in aqueous matrices [5–8], which are primarily based on solid phase extraction, silylation and detection by gas chro- matography (GC)–mass spectrometry (MS) or LC–MS. Hydrophobic organic pollutants in aquatic environments tend to deposit and accumulate on the solid phases such as sediments, although the magnitude of which is dependent on EDCs and sediment properties. Limited study is de- voted to the analysis of EDCs from solid samples because of the complexity of sample processing and requirement of low detection limit. Recently, different extraction and 0021-9673/$ – see front matter © 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.chroma.2004.03.030