The Trouble With Water
Admit it. With all the headlines about unsafe drinking water, have you ever wondered what might actually be in the water where you live?
Beyond lead there are any number of things that can get into our water supply, such as chemicals, microbes, pesticides, and other potential toxins, just to name a few. At most water municipalities, for example, water is tested for more than a hundred different compounds that are both intentionally and unintentionally found in drinking water. All of those inorganic compounds, microbials, and chlorine disinfectant are measured in the parts per million on a regular basis as required by law. 1
That seems impressive. Until you realize that we live in a world where untold amounts of engineered nanoparticles (ENPs) used in everything from catalytic convertors to sunscreen are finding their way into our drinking water supply at molecular levels that until recently have been difficult to quantify. What has changed?
A New Level Of Precision
The introduction of single particle inductively coupled plasma-mass spectroscopy (SP-ICP-MS) now allows scientists the ability to detect elements down to the single particle mode quickly and more precisely than current light-based technologies. 2
At Missouri University of Science and Technology, researchers employed a PerkinElmer NexION® 350D ICP-MS that was outfitted with a Syngistix™ Nano Application Module to track the presence of several inorganic nanoparticles in drinking water from the Mississippi River, including titanium dioxide (TiO2) silver (Ag), gold (Au), zinc oxide (ZnO), and cerium dioxide (CeO2). While these compounds are widely used in a number of commercial products and applications, some are considered to “have a relatively high acute toxicity...,” writes Ariel R. Donovan, the lead author of three studies on the subject. 3
Because of the chemicals’ potential to cause harm, Donovan and her colleagues successfully calibrated the NexION ICP-MS to monitor for the presence and apparent removal of these nanoparticles during a typical drinking water treatment process at three facilities. In so doing, they relied on a series of highly regulated experiments using a six-gang stirrer system to simulate the water treatment steps that are typically employed in real-world systems. In one phase, the scientists used ultra-pure water containing measured amounts of the nanoparticles. They then repeated the experiments using water from the Mississippi River both with and without the added chemicals. All of the experiments included lime softening, alum coagulation, and disinfection, to simulate the actual water treatment process.
The Results, Please
According to the research team, the NexION proved its superiority in detecting nanoparticle size, size distribution, particle concentration, and dissolved ion concentrations in master samples – all simultaneously without the need for lengthy sample preparation or data processing.
“As more complex nanoparticles are being used and introduced in various consumer products, there is an increased need for pilot studies to further investigate the impact of these emerging chemicals on the environment and, subsequently, human health,” the research team concluded. “SP-ICP-MS can serve not only for the pilot research, it may also serve as a rapid tracking technology as part of routine water quality testing for nanoparticles.” 4
As for the quality of the drinking water? “The selected nanoparticles were nearly completely (97 ± 3%) removed after lime softening and alum coagulation/activated carbon adsorption treatments,” Donovan said. “Additionally, source and drinking waters from [the] three large drinking water treatment facilities utilizing similar treatments with the simulation test were collected and analyzed by the SP-ICP-MS methods. Ti-containing particles and dissolved Ti were present in the river water samples,” she noted, “but Ag and Au were not present. Treatments used at each drinking water treatment facility effectively removed over 93% of the Ti-containing particles and dissolved Ti from the source water.” 5
Equally important, the American Water Works Association presented two awards to Donovan and the Missouri S&T research team for their work in developing a new SP-ICP-MS methodology for testing nanoparticles in drinking water. 6
- Aquarion Water Company, “2013 Water Quality Report For Customers in the Greater Bridgeport [CT] System,” Aquarion, 2013.
- Ariel R. Donovan, Honglan Shi1, Craig D. Adams, Chady Stephan, “Monitoring Cerium Dioxide And Zinc Oxide Nanoparticles Through Drinking Water Treatments Using Single Particle ICP-MS,” PerkinElmer Application Note, 2016.
- Ariel R. Donovan, Craig D. Adams, Yinfa Ma, Chady Stephan, Todd Eichholz, Honglan Shi, “Detection Of Zinc Oxide And Cerium Dioxide Nanoparticles During Drinking Water Treatment By Rapid Single Particle ICP-MS Methods,” Analytical and Bioanalytical Chemistry, July 2016, Volume 408, Issue 19, pp 5137-5145. See also, Ariel R. Donovan, Craig D. Adams, Yinfa Ma, Chady Stephan, Todd Eichholz, Honglan Shi, “Single Particle ICP-MS Characterization Of Titanium Dioxide, Silver, And Gold Nanoparticles During Drinking Water Treatment,” Chemosphere, February 2016.
- Ariel R. Donovan, et. al., “Monitoring Cerium Dioxide And Zinc Oxide Nanoparticles Through Drinking Water Treatments Using Single Particle ICP-MS,” op.cit.
- Peter Ehrhard, “Missouri S&T Student Earns Awards For Tracking Nanoparticles In Water,” Missouri S&T News and Events, February 10, 2016.