{'fraction_non_alphanumeric': 0.039927404718693285, 'fraction_numerical': 0.03145795523290986, 'mean_word_length': 5.194756554307116, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Solid-phase extraction followed by deep eutectic solvent based dispersive liquid–liquid microextraction and GC-MS detection of the estrogenic compounds in wastewater samples

Solid-phase extraction (SPE) combined with deep eutectic solvent based dispersive liquid–liquid microextraction (DES-DLLME) has been developed as a highly sensitive technique for the ultra preconcentration of estrogenic compounds in wastewater samples prior to their analysis by gas chromatography-mass spectrometry (GC-MS). This coupling not only allows for the extraction of compounds from complex matrices such as sewage and wastewater, but also provides very high enrichment factors. In this technique, a new deep eutectic solvent (DES) was prepared by blending citric acid monohydrate and 1-octyl-3-methylimidazolium chloride at a molar ratio of 1 : 1. Variables affecting the performance of both steps were thoroughly investigated. Under the optimized conditions, the enrichment factors and extraction efficiency are between 33 000–41 000 and 55–68%, respectively. The SPE–DES-DLLME provided a high enrichment factor for estrogenic compounds. The limits of detection (LODs) are in the range of 0.01–0.05 ng L−1 and the calibration graphs are linear in the range of 0.03–50 ng L−1. The values of relative standard deviation (RSD) for intra-day and inter-day based on seven replicate measurements of 0.50 ng L−1 of estrogenic compounds and 0.30 ng L−1 for the internal standard in wastewater were in the range of 1.5–2.5% and 2.6–3.8%, respectively. The relative recoveries of wastewaters which have been spiked with different concentrations of target compounds are 90–108%.