Advancing Water Analyses

Water is life. Indeed, its existence on Mars has driven the search for life on the red planet (see Art of Analysis). Water is also a powerful solvent, carrying a myriad of chemicals, many of which undergo chemical conversion in the resulting complex mixture. Importantly, the quality of water entering a processing facility can affect the purity of the polished product. But, how much control do we have? Monitoring water and limiting toxic chemicals introduced into our water system can improve the process, and regulations govern what we know to be dangerous. However, there is a struggle to predict what new contaminants should be restricted.

At Pittcon 2015, we presented the conundrum of water quality in our session on emerging contaminants and healthy water. At the University of South Carolina, exquisite analyses based on chromatographic separation and high-resolution mass spectrometry provide powerful insight into the complex and dynamic mixture that is our municipal water. Analyzing water for pharmaceuticals, illegal drugs, food additives, pesticides, herbicides, and consumer products can reveal much. For example, penta and octa brominated contaminants (originating from polybrominated diphenyl ethers once used in flame-retardants) are toxic (1). A deca-brominated contaminant should be safe, except that it degrades to these more toxic constituents (1). So we must ask: “Is this an isolated problem?” Perhaps not. Iopamidol is an invaluable imaging agent in medicine; it is safe for consumption and improves lives. Yet, when it is excreted by the body and subjected to chlorination, a 200-gram dose of a critical medical chemical becomes a toxic iodinated disinfection by-product (2). How could this have been anticipated? If we put the power of an LC-MS into a wastewater treatment facility, the operator would know, but such equipment and knowledge comes at a cost. What if we reduced the cost by using non-toxic, disposable microfluidics to make simple and robust sensors? This would allow the operator to identify those species that are intolerable in the water system, those that can be better removed with changes in processing, and those that are indicators of anthropogenic contamination of natural waters. When knowledge is power, such strategies make sense.

At Oregon State University, researchers use polycaprolactone to build portable devices by printing simple patterns on laboratory filter paper (3, 4). The work – supported by the Bill and Melinda Gates Foundation – paints an interesting picture; colorimetric assays for bromide using the technology, for example, can easily recognize the yellow spots of hydraulic fracturing (fracking) fluid leakage. Paper is cheap and the human eye is the ultimate convenient detector.  The measurement can be performed on a tight budget for less than one dollar with no training required. And, for an additional 100 dollars, a stable light source and USB adapter can be added to the device to improve quantification; another option is to use a mobile phone for detecting and data sharing. With these relatively low-cost tools, on-site monitoring becomes achievable for bromide and the principle may be applied to any other contaminant that can be adapted to colorimetric detection. But let’s return to the question about what is not known. There are 800 known endocrine disrupting compounds, but the bigger threat comes from those compounds, metabolites or mixtures for which toxicity is not yet known. In our waterways, for example, dying freshwater fish tell us when agricultural runoff, antibacterial additives in soap, or pharmaceuticals excreted by humans, lead to a toxic recipe for aquatic life. So, we can learn a lot by monitoring wildlife.  Population declines or sudden die-offs can be signs of caution, as can indicators of reproductive dysfunction, compromised immune systems, cancer, neurotoxicity and behavioral effects in fish living in these waters. Sediment, water, passive samplers, and fish may hold secrets that led a U.S. Geological Society (USGS) research team to assay 138 chemicals collected from samples at six different sites throughout the Potomac River basin – which supplies water to more than five million people in Maryland, Pennsylvania, Virginia, Washington D.C., and West Virginia in the USA (5, 6). What can be done when human activities create chemical cocktails in our water system? Researchers at West Virginia University demonstrated the power of analyzing circulating steroids in fish by using a rapid capillary electrophoresis method to separate multiple steroids within five minutes, enabling detection of steroids in individual fish using UV-visible absorbance (7). When adapted for the analysis of a single zebrafish weighing only 1.5 grams, this method generates nanomolar detection limits and provides insight into hormonal responses to chemical exposure that correlates well with physiological endpoints. Monitoring changes in multiple circulating steroids enables researchers to screen chemicals rapidly for endocrine disruption. With information about specific changes in estrogens, androgens, and progestogens, the mechanisms of dysfunction can be better elucidated. After we presented the above examples in our Pittcon session, we had a lively panel discussion, which increases the likelihood that this topic will be included in other national and international meetings. Being able to show how integrating technologies and how analytical chemistry can tackle such a complex problem, such as water safety, fires debate and, above all, we hope that scientists and citizen scientists will seek answers to these environmental issues with new enthusiasm. Certainly, further research must be supported to address these important questions (8).

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