Researchers develop rapid test strips to detect swimming water contamination

April 30, 2012

    researchers at McMaster University have developed a rapid testing method using a simple paper strip that can detect E. coli in recreational water within minutes. The strips are coated with chemicals that react to the bacteria and change colour to indicate its presence. The new tool could can close the gap between outbreak and detection, improving public safety. Photo by JD Howell.
Urban beach closures due to coliform outbreaks have become disturbing signs of
summer, yet water-testing technology has never been fast enough to keep up with
changing conditions, nor accessible enough to check all waters.

Now, researchers at McMaster University have developed a rapid testing method using a
simple paper strip that can detect E. coli in recreational water within minutes. The new
tool can close the gap between outbreak and detection, improving public safety.

The new strips are coated with chemicals that react to the bacteria, and are printed
using inkjet technology similar to that found in standard desktop printers. Within 30
minutes of sampling, the paper changes colour to indicate the presence of E. coli, with
colours coded to represent different forms and concentrations of the bacteria.

Scientists from the Sentinel Bioactive Paper Network have created and validated the
viability of the test strip, which can detect potentially harmful concentrations of E. coli
in water quickly and simply, with much greater accuracy than existing portable
technology.

The Natural Sciences and Engineering Research Council of Canada (NSERC) funds
Sentinel, a strategic research network that spans the country and is based at McMaster.
Several dozen researchers are involved in its initiatives.

"Coliforms are always a big problem," said the paper's lead author John Brennan, a
McMaster chemistry professor who holds the Canada Research Chair in Bioanalytical
Chemistry. "The methods used to detect outbreaks are slow, and tend not to be
portable, as they often need a lab-based amplification step prior to testing, causing a
time lag between an outbreak and a beach closure."

Bioactive paper is both old and new, Brennan says. Since the late 1950s, physicians have
been using bioactive paper to test for glucose in urine. In the last several years, the area
has expanded quickly and research has become very competitive as scientists work on
new applications.

"It's always a race," Brennan said.

In the future, the test strips should make it possible for consumers to check their water
affordably and easily, without additional equipment, scientific knowledge or long waits.

"One of the problems right now is that there is no simple, fast and cheap way to test
recreational water, and certainly nothing out there in the realm of rapid tests for
drinking water," Brennan said.

Field testing of the prototype strips is planned or under way in Canada and across the
globe, in regions where untreated water poses particular health hazards. The results of
these studies will help to refine the test strips and may lead to strips that are sensitive
enough to tell whether water is safe enough to drink, said Brennan.

The standards for safe drinking water are hundreds of times tighter than those for safe
swimming water. Typically, limits for safe swimming allow for a maximum of 100 to 500
cells of E. coli in 100 mL of water, depending on jurisdiction. For water to be considered
safe for drinking, there cannot be even one cell in 100 mL - a little less than half a cup
of water.

The next stage of pre-commercial development of the test strips is already funded by
NSERC through a Phase I Idea to Innovation grant. Commercialization of a final product
could take as little as two to three years.

The work is described in a paper published online in the journal Analytical and
Bioanalytical Chemistry
.