Background and Objectives Produced water for future reuse is a key component of Qatar's Water Security Grand Challenge (WSGC) and forward progress within the Grand Challenge is dependent on comprehensive characterization and potential risks. To date, only major compounds of produced waters are characterized. For safety reason, a global fingerprint of both natural and anthropogenic trace organic and inorganic constituents must be created before any treatment or reuse. The main objective of this innovative strategy is to reach an accurate, non-specific monitoring of organic and inorganic ultra-trace compounds by mass spectrometry. Methods Produced water samples were collected in Qatar's oil field from various Qatar's produced wells with a high water cut in order to evaluate the water quality and to select produced waters for further studies for treatment and reuse. To highlight the benefit of this innovative analytical approach, the study was focused on highly hydrophilic compounds which remain in the aqueous phase even after oil separation. Naphtenic acids, Fluorinated acids, BTEX biodegradation byproducts, halo acetic acids, and trace metals (Ni, Cr, Fe, Cd, U etc.) are related to produced water characteristics, oil and gas industry and well tubing. The quantifications were firstly completed by UHPLC-ESIqQqTOF Maxis HD (Bruker) and by ICP-MS Aurora Elite (Bruker). All analyses were performed in QEERI laboratories. The direct analyses of produced water were based on synergic used of ultra high pressure liquid chromatography, non-specific high resolution and inductively coupled plasma mass spectrometry. The development of robust, accurate and high end methods allows us to generate high quality data for immediate chemical information extraction, long term inter sample comparison and long term raw data storage for further studies. The in silico storage of water's nonspecific fingerprint is an interesting and promising alternative to long term storage of diluted media like water samples which are always critical. Results The current study was performed using Qatar's produced waters and on Congo and Angola's produced waters as reference waters. Despite the sub-ppb level quantification limit, the results of Qatar's produced waters analyzed do not show significant trace of halogenated acetic acids, perfluorinated compounds or BTEX biodegradation byproducts in comparison to the African's produced waters. Trace elements and radionuclides analysis are currently ongoing. Conclusions Here, we introduce innovative analytical strategies on produced water by synergic used of high resolution and multi-elemental mass spectrometry for accurate fingerprint on organic and inorganic ultra-trace contaminants study of water characteristics. Its part of an ongoing process focused on optimizing and developing analytical approaches suitable for Qatar's produced water quality prior to sustainable reuse. The methodology developed (isotopic dilution, standard addition…), is the first bimodal study of its kind. It can be used in the future to perform a non-specific screening of ultra-traces acids, metals and radionuclides compounds. The relative analytical results are being used to drive research efforts within the WSGC.


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