Nontoxic Water Screening System Blasts Off

September 15, 2009

University of Utah chemists have developed a new nontoxic water testing system that they recently sent via the Discovery shuttle to be tested over six months in the International Space Station.

Astronauts there have two water purification systems--the Americans use iodine and the Russians use colloidal silver. Too little of either means microbe growth while too much iodine can cause thyroid problems and too much silver turns the skin grayish-blue, permanently. To test the water, the astronauts usually send samples back to Earth and wait for the results. Until now.

University of Utah chemistry professor Marc Porter led the creation of a two-part water testing system ten years in the making. A water sample is injected into a cartridge containing a membrane-covered disc of a nontoxic reactive chemical--5-(dimethylaminobenzylidene) rhodanine (DMABR) for silver and polyvinylpyrrolidone (PVP) for iodine. The cartridge is then loaded into an industrial sensor usually used commercially to measure automotive paint color. The sensor can determine exactly how much iodine or silver is in the water sample. If all goes well, the astronauts will be able to correctly calibrate water disinfection in space.

The chemists are currently reworking their color-sensitive NASA system to detect levels of arsenic and heavy metals such as cadmium and lead in water on Earth. The inexpensive color-based detection systems out there now tend to be unreliable, says Lorraine Siperko, a senior research scientist on the University of Utah team. The chemists' goal is to create reliably reactive cartridges that cost less than a few dollars each.

"We want to make something that’s affordable and could be used in many parts of the world, especially where they have limited resources," Siperko says. "We want to make it easy, so you don’t have to be an astronaut."

Top: University of Utah chemist Lorraine Siperko has a zero gravity moment while testing a water monitoring system aboard a NASA aircraft. Bottom: Two of the color sensors. Credit: Courtesy of NASA.