Tales of mass spectrometry applications: Detection of legacy and emerging contaminants in the environment
Noguera Oviedo, Katia Maria
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Environmental contaminants are naturally occurring, manufactured or man-made compounds which have been discovered to pose a threat to living organisms. The advancement in our knowledge on past and present contaminants in the environment has been the result of the appearance and evolution of highly sensitive and powerful analytical instrumentation that has allowed the identification and trace quantification of contaminants in complex environmental matrices. The overall goal of this research was to develop and optimize mass spectrometry techniques for the analysis of emerging contaminants (e.g., hormones) and legacy pollutants (e.g., pesticides and metals) in different environmental matrices. The first part of this work focuses on the optimization of solid-phase extraction (SPE) methods for the analysis of estrogens and their conjugated metabolites in dairy manure. Multiple techniques were used to obtain information different pieces of information that allow a complete assessment on estrogen concentrations and estrogenic potential of the manure samples. Liquid chromatography tandem mass spectrometry (LC/MS/MS) was used for the analysis of conjugated estrogens; gas chromatography mass spectrometry (GC/MS) for the analysis of free estrogens and yeast estrogen screen (YES) assay was used to determine the overall estrogenic potential of the manure. Following development, these methods were used to assess estrogen and estrogenicity in a full-scale dairy manure anaerobic digester. The total hormone concentrations were not found to decrease significantly during digestion, however, the relative composition of the estrogens changed from E2α (65%) being the predominant species before digestion to mostly E1 (72%) after digestion. This conversion process has important implications because E1 was more estrogenic than E2α. Total E2 equivalents associated with E1, E2α and E2β concentrations as determined by GC/MS indicate that E1 was the most important contributor to the endocrine-disruption activity of the treated manure. Estrogens find their way into streams via different sources such agricultural run-off of land applied manure and WWTPs. These compounds are not yet regulated but different strategies are used to control nutrient pollution which share source, with estrogens in the environment. Therefore, the impact of different nutrient management (agricultural and urban best management practices or BMPs, advanced wastewater treatment, and combined sewer overflows or CSOs) on estrogens in streams was examined. Estrogens were analyzed by LC/MS/MS while estrogenicity was measured using the BLYES assay. Estrone was the main estrogen found in the streams. The concentrations of estrone with BMPs decreased by 44-69% relative to unrestored streams without BMPs while over 99% of estrone was removed from wastewater during nitrification/denitrification as a part of advanced wastewater treatment. Results suggested that watershed nutrient management strategies have the potential to remove estrogens from point and nonpoint pollution sources. Pesticides play an important role in our society in areas such as food security and control of diseases. However, there is a global concern due to their widespread in the environment and intrinsic toxic nature. A method for the analysis of different pesticide families in sediments was developed using a Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) and gas chromatography triple quadrupole mass spectrometry (GC-QQQ-MS/MS). The method developed was applied to sediment samples from Colombia, a country where the lack of knowledge on the levels of these pollutants make significant the need of identifying their occurrence and source of exposure to assess their potential ecological risk and environmental fate. Pesticide levels were determined in sediments from two significant aquatic environments in Colombia: the Magdalena River, the main river of and source of fresh water in Colombia and the Cartagena Bay that receives discharges from the Magdalena River. Results show the occurrence of pesticides with total levels between 0.29-16.48 ng/g in the river, and 1.47-14.01 ng/g in the Cartagena Bay. Additionally, a methodology for the analysis of metal in sediments using inductively coupled plasma mass spectrometry (ICP/MS) was validated and applied to the Colombian sediments described above. The data indicates that the Magdalena River has lower levels of metal content (0.4-40.3 mg/kg) compared to the Cartagena Bay (1.1-231.4 mg/kg), which was expected because the bay serves as a recipient of the pollution brought by the river. These data serve as a baseline for the pollution of pesticides and metals in sediments in Colombia.