Texas A&M Technology To Detect Trace Amounts of Fecal Contamination

Interested in Laboratory?

Get Laboratory articles, news and videos right in your inbox! Sign up now.

Laboratory + Get Alerts

Researchers at Texas A&M University are developing technology that will detect fecal matter contamination in water that are thousandths and even millionths of times smaller than those found by conventional methods.

Working with a team of collaborators, Vladislav Yakovlev, professor in the Department of Biomedical Engineering, has developed an ultrasensitive method that can detect molecules associated with human and animal fecal matter in water systems. These extremely small indicators have been traditionally difficult to detect but can signal greater levels of contamination, which can lead to illness and even death.

The team’s research is funded by the National Science Foundation and is featured in the journal Proceedings of the National Academy of Sciences. It details the development of technology that Yakovlev characterizes as affordable, highly sensitive, easy to implement and capable of delivering analysis of water samples in real time. That combination of benefits gives the system a leg up on other detection technologies, making it ideal for use not only in the United States but in developing countries, which often face water quality issues.

Animal and human waste can contaminate recreational and source waters, carrying diseases such as polio, typhoid and cholera. This form of contamination can even result in environmental crises, such as devastation to the aquatic population and red-tide blooms, Yakovlev notes. These types of contamination events might be mitigated or even avoided if samples from water systems are more thoroughly analyzed. In other words, finding trace amounts of contaminants such as fecal matter in water systems can sound the alarm for a serious contamination events because these trace amounts likely originate from a larger source in the water system.

However, detecting these trace amounts isn’t easy, especially in a timely manner. High costs, sample-size limitations and lengthy analysis times have prevented environmental researchers from using highly sensitive techniques that can deliver real-time analysis.

Yakovlev and his colleagues are poised to change things with an innovative approach to detecting urobilin. Urobilin is a byproduct excreted in the urine and feces of many mammals, including humans and livestock such as cows, horses and pigs. Urobilin molecules are small and diffuse quickly so they easily occupy large volumes, such as lakes and reservoirs.

In addition, urobilin possesses another interesting property; it glows — or more accurately, it can be made to glow. When mixed with zinc ions, urobilin forms a phosphorescent compound. This means if urobilin is present in a water sample — and zinc ions have been added — the sample will give off a greenish glow when examined under an ultraviolet light. There’s just one catch: In some samples with low concentrations of urobilin, the glow, or phosphorescent emission, can be weak, making it difficult to analyze the sample. Researchers must be able to thoroughly excite the sample (causing the reaction), observe the glow and then measure it to perform an accurate analysis.

Yakovlev and his team have developed technology that lets them thoroughly excite extremely small amounts of urobilin in large samples of water and then efficiently collect the resulting phosphorescent emission, regardless of how weak that emission might be. It’s done with the help of device researchers refer to as an “integrated cavity.”

The integrated cavity is essentially a hollow, cylindrical container manufactured in Yakovlev’s laboratory. A water sample is placed inside the cylinder where it interacts with zinc ions, and a laser light is beamed into the object and onto the sample through a small hole. The light excites the urobilin compound present in the sample, causing it to glow. The only way for the light to exit the cylinder is through the hole that it initially entered. Not only does this ensure that all the light that enters the cylinder is used to excite the entire sample, it also enables researchers to efficiently collect the resulting phosphorescent emission so it can be directed to a photo detector, such as a spectrometer, for analysis.

Employing the integrated cavity in their detection efforts, Yakovlev and his team have detected the presence of urobilin down to a nanomole per liter. What’s more, the technology provides actual concentration levels of the contaminant, and it does so much quicker than other methods.

“We can demonstrate detection of ultralow concentrations of urobilin in solution,” Yakovlev says. “This is a huge improvement in terms of sensitivity, and our technique has tremendous potential for analysis of global drinking water supplies, particularly in developing nations and following natural disasters, where sophisticated laboratory equipment may not be available.”

Another key element of the technology, which can be produced for a few hundred dollars, is its ability to analyze large samples. Conventional methods cannot analyze large samples. This is a problem because it is unlikely that an accurate analysis of an overall water system can be derived from a small sample. For example, researchers might collect a small sample that is free of the contaminant, but that doesn’t mean the entire water system is contaminant free. A larger sample gives researchers a better predictive power about the water that the system contains.

“The bigger the sample, the better,” Yakovlev says. “And with our technology the sensitivity scales with the amount of water in our sample. Using one liter will increase sensitivity by a factor of 20, and an additional 10 liters result in another order of magnitude increase in sensitivity.”

Yakovlev and his team are working to commercialize the technology for urobilin detection. Because it delivers nearly instant results, it could serve as the basis for in-home detection systems that alert users if the water coming from a faucet is suddenly contaminated. Think smoke detector for a water faucet. The technology can be used for detection of other types of toxic compounds in liquids and gases.

Yakovlev’s collaborators are Marlan O. Scully and Edward S. Fry — professors in the Department of Physics and Astronomy at Texas A&M — and graduate students Joel N. Bixler, Michael Cone, Brett Hokr, John Mason and Ellie Figueroa.



Discussion

Comments on this site are submitted by users and are not endorsed by nor do they reflect the views or opinions of COLE Publishing, Inc. Comments are moderated before being posted.