Advancing towards universal screening for organic pollutants in waters

Abstract

Environmental analytical chemists face the challenge of investigating thousands of potential 13 organic pollutants that may be present in the aquatic environment. High resolution mass 14 spectrometry (HRMS) hyphenated to chromatography offers the possibility of detecting a 15 large number of contaminants without pre-selection of analytes due to its accurate-mass full-16 spectrum acquisition at good sensitivity. Interestingly, large screening can be made even 17 without reference standards, as the valuable information provided by HRMS allows the 18 tentative identification of the compound detected. In this work, hybrid quadrupole time-of-19 flight (QTOF) MS was combined with both liquid and gas chromatography (using a single 20 instrument) for screening of around 2,000 compounds in waters. This was feasible thanks to 21 the use of atmospheric pressure chemical ionization source in GC. The screening was 22 qualitatively validated for around 300 compounds at three levels (0.02, 0.1, 0.5 µg/L), and 23 screening detection limits were established. Surface, ground water and effluent wastewater 24 samples were analyzed, detecting and identifying a notable number of pesticides and 25 transformation products, pharmaceuticals, personal care products, and illicit drugs, among 26 others. This is one of the most universal approaches in terms of comprehensive measurement 27 for broad screening of organic contaminants within a large range of polarity and volatility in 28 waters. 29 30 KEYWORDS: liquid chromatography, gas chromatography, quadrupole time of flight 31 mass spectrometry, universal screening, water samples, organic micropollutants 32 33 3 34 INTRODUCTION 35Over the last decades, environmental pollution has become a matter of increasing concern 36 due to the high number of both regulated and unregulated organic pollutants that can be 37 present in environmental waters. The majority of these compounds, such as pesticides, 38 pharmaceuticals, drugs of abuse, surfactants, biocides, personal care products, sweeteners, 39 etc. are originated by human use. They can enter in the surface water (and even groundwater) 40 mainly via treated and untreated wastewater [1][2]. Despite the evident advances in analytical 41 chemistry, the comprehensive determination of organic contaminants in waters is still a 42 challenge at present. The main difficulty arises from the elevated number of compounds (in 43 addition to their metabolites and/or transformation products) that may be present in the 44 samples. This fact, together with the very different physico-chemical properties of analytes, 45makes the application of a single analytical methodology, appropriate for all potential 46 contaminants, unfeasible. 47 Most analytical methods developed until now have used chromatographic techniques coupled 48to mass spectrometry (MS) analyzers, as single quadrupole or ion trap, and in the last decade, 49 triple quadrupole. In these target methods, the list of analytes rarely exceeds 200-300 50 compounds, and relevant contaminants other than the ...

Suspect screening of large numbers of emerging contaminants in environmental waters using artificial neural networks for chromatographic retention time prediction and high resolution mass spectrometry data analysis

“…These covered a large range of molecular hydrophobicity (logK ow -3 to 9). Information relating to 595 standards was available (Bade et al, 2015), however after transforming the compounds using SMILES codes, some errors were observed, leading to incomplete data, and a further 42 were removed from the initial ANN method development (Section 3.1) to use in a subsequent blind test (Section 3.2) .Further details relating to these compounds can be found elsewhere (Bade et al, 2015;Hernández et al, 2015b).…”

Critical evaluation of a simple retention time predictor based on LogKow as a complementary tool in the identification of emerging contaminants in water

“…Details relating to the standards can be found elsewhere [17]. Retention times were obtained by injecting mixed working standard solutions (25 µg/L or 50 µg/L, diluted from mixed standard solutions in methanol or acetonitrile with water).…”

Screening of pharmaceuticals and illicit drugs in wastewater and surface waters of Spain and Italy by high resolution mass spectrometry using UHPLC-QTOF MS and LC-LTQ-Orbitrap MS

“…A qualitative validation was previously performed using a similar analytical procedure based on LC-QTOF MS measurements, and the empirical screening detection limits (SDL) and limits of identification (LOI) in different type of water samples were established for some of the compounds included in the present work. For most compounds evaluated SDLs were 0.02 or 0.1 µg/L (Diaz et al, 2013;Hernández et al, 2015). For compounds where no standards were available, the database included data regarding fragment ions and molecular formula from literature or online databases such as MassBank (Horai et al, 2010).…”