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Earlier this year, a state-of-the-art liquid chromatography-tandem mass spectrometer (LC-MS/MS) was installed in the laboratory of Michigan State University (MSU) Plant Soil and Microbial Sciences associate professor Hui Li.

Liquid chromatography-mass spectrometry (LC-MS) enables scientists to examine pharmaceutical chemicals in water, soil and other natural resources. Using this advanced technique they can identify, characterize and quantify a vast range of chemicals in the presence of other compounds.

Detecting nanogram-size concentrations

An indispensable tool in the lab, LC-MS has helped advance science by combining the physical separation capability of liquid chromatography with the analysis capability of mass spectrometry. The new spectrometer is more sensitive and convenient to use than the instrument it replaced. MSU AgBioResearch contributed funds for the equipment.

The accurate quantification of antibiotics in soil and water using the LC-MS/MS is essential to evaluating their fate and transport in the environment, and assessing their potential risks to microbial communities and humans. One of the major challenges in this line of research is to identify and quantify the extremely low concentration of antibiotics, considered as chemicals of emerging concern (CECs), in environmental matrices.

Li said the new LC-MS/MS can detect the presence of pharmaceuticals in water down to the levels of nanograms (one billionth of a gram) per liter.

80 percent of streams contaminated

Li said he was prompted to study CECs after a United States Geological Survey (USGS) report released in 2002 showed that 80 percent of stream samples taken from 30 states, including Michigan, were contaminated by pharmaceuticals, hormones and other organic wastewater contaminants.

“Pharmaceuticals are of particular concern because they have high bioactive potentials. They have di‡fferent physicochemical properties, and more complicated chemical structures than the conventional organic contaminants. I saw this clearly as an area in need of more scientific information to fill the knowledge gaps, and I wanted to be able to help.”

One concern is that the pharmaceuticals, either in the water system or in land-applied biosolids, can possibly have negative impacts on ecosystems such as enhancing the development and proliferation of antibiotic resistance in bacteria.

“Pharmaceuticals are designed to stay for a short time, take e‡ffect and exit the body,” Li said. “So the assumption is that, when these chemicals get into the environment, they will disappear or last a very short time. But that’s just not the case.

Focus on tetracyclines

Wastewater treatment plants are designed to treat heavy metals, nutrients — nitrogen and phosphate, or some other organic compounds, but not specifically for pharmaceuticals.

The team has conducted studies that showed that only 60 to 90 percent of CECs can be removed from wastewater treatment plants. As a result, a fair amount of CECs are still released to the surrounding environments.

Through a project funded by the National Science Foundation, MSU scientists are exploring the issue of antibiotic resistance as it relates to antibiotics in soil and water. They are mainly focused on tetracyclines — the most commonly used antibiotic in animal feeding operations, accounting for an estimated 40 percent of all antibiotics use in animal agriculture.

Their research results indicate that tetracycline specifically the zwitterion species could be the major speciation to exert selective pressure on bacteria such as E. coli for development of antibiotic resistance.

“Unfortunately, pharmaceuticals end up in the environment as a mixture of multiple chemicals, and we don’t know much about the ecological e‡ffects of the mixture,” Li said. “The concentrations of these pharmaceuticals are fairly low by themselves, but a mixture of these pharmaceuticals could have potentially dangerous impacts to ecosystem and human health.”

– excerpted from “100 times More Sensitive,” Futures (Spring/Summer 2015) by Holly Whetstone

– Photo:  State-of-the-art liquid chromatography-tandem mass spectrometer (LC-MS/MS) was installed in the laboratory of MSU Plant, Soil and Microbial Science associate professor Hui Li in March. The piece of equipment can detect the presence of pharmaceuticals down to a nanogram. Photo by Kurt Stepnitz.

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