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Development And Application Of Bioanalytical Tools For The Determination Of Emerging Contaminants In Wastewater Treatment

Congress: 2015
Author(s): RACHEL GOMES, SHRIDHARAN PARTHASARATHY, CATHERINE ORTORI, DAVID BARRETT
UNIVERSITY OF NOTTINGHAM1

Keyword(s): Sub-theme 13: Non-conventional sources of water,
AbstractIntroduction: Bioactive chemicals such as pharmaceuticals and steroids are an emerging environmental and human health issue in water. Their presence in wastewater and aquatic environments is of global concern due to observations of severe reproductive abnormalities such as intersexuality in aquatic wildlife [1]. In England and Wales, Water Companies are responsible for wastewater treatment plants (WWTPs) and must adhere to regulatory drivers that ensure wastewater effluent does not impact the quality of the receiving rivers and the wildlife within [2]. Legislation in the fields of water and the environment is placing increasing emphasis on pollution control measures to protect surface waters e.g. the 2013 Watch List for one steroid and two pharmaceuticals requiring targeted European Union-wide monitoring to support the prioritisation process in future reviews of the priority substances list. Though control measures to reduce pollution at source may be appropriate for some BACs (e.g. nonylphenol and ethoxylates), this is unfeasible for steroids and pharmaceuticals due to their origin and use. They enter the WWTP as a product of human excretion, either produced naturally in the body or following ingestion for health, wellbeing or illicit drug use.

Materials and Methods: Drugs were accurately weighed to prepare stock solutions of individual compounds at a concentration of 0.1 mg/mL in methanol. These stock solutions were mixed to obtain a stock solution mixture of all the selected 36 drugs, concentrations of each analyte in this stock solution. Effluent wastewater samples were collected from a WWTP in the East Midlands. After filtering through 0.45μm GF/C filters using Sartorius and Buchner filtration systems (Fisher Scientific, Loughborough, UK), the samples underwent solid phase extraction (SPE) to both concentrate and clean up the sample (Waters, UK). The target compounds were extracted from effluent water samples by Oasis MCX (150 mg, 6 mL) solid phase extraction (SPE) cartridges. The compounds were spiked in triplicate in 500 mL of effluent wastewater to determine the recoveries. Using the combination of exact mass liquid chromatography tandem mass spectrometry (LC-MS/MS) and quadrupole-linear ion trap (QTRAP) LC-MS/MS, screening of a number of processed samples of WWTP effluent was carried out. Enhanced Product Ion (EPI) and Multiple Reaction Monitoring (MRM) data from the QTRAP LC-MS/MS were analysed using Analyst (software).

Results and Discussion: The mass spectrometer settings were optimised with a direct infusion of working standard solutions. For all compounds, the two most abundant product ions produced from each precursor ion were chosen as the ion transition in order to comply with the criteria needed for qualitative and quantitative methods. The characteristic MS/MS parameters: collision energy (CE), declustering potential (DP) and dwell time have been optimised separately for each analyte. The analyses were performed in both positive and negative ionisation mode.Considering the wide array of species with different physicochemical properties, a generic sample treatment procedure was selected, based on Oasis MCX SPE cartridge. For reverse osmosis (RO) and effluent wastewater (EWW), the recovery was higher than 70% for 23 and 12 out of the 36 compounds, respectively.The proposed methods, successfully applied to the determination of these target compounds in environmental water samples collected in United Kingdom demonstrated the presence of significant amounts of a range of bioactive chemicals detailed in Table 1, indicating that conventional wastewater treatment plants cannot efficiently remove most of the bioactive chemicals. The concentration of the bioactive chemicals was then corrected for the recovery.

Table 1: Determination of bioactive chemicals in effluent wastewater in the UK (n=3).

Concentrations of trimethoprim, sulphapyridine, erythromycin and bezafibrate were found to be unusually high in the effluent wastewater matrix. Many of the compounds present in wastewater effluent indicating that conventional wastewater treatment plants cannot efficiently remove most of the bioactive chemicals and are consequently discharged into the rivers.

Conclusions: In the present work, a simple and fast multi-residue method based on SPE followed by LC--MS/MS has been developed for the simultaneous extraction and analysis of 36 bioactive chemicals in wastewater samples. The higher selectivity and structural information provided by the product ions mass spectra allows reliable confirmation of the target compounds in these complex matrices. 1.Gomes, R. L., Meredith, W., Snape, C. E. and Sephton, M. A. (2009) Conjugated steroids: analytical approaches and applications. Anal. Bioanal. Chem. 393, 453-458.
2.Tyler, C. R. (2001) In Evidence for endocrine disruption in European Wildlife, especially fish, Second Status seminar endocrine disrupters, Berlin, Germany, 2nd-4th April 2001, Umwelt Bundes Amt. Berlin, Germany, 49-54.

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