IISc Bengaluru researchers develop cheaper, simpler way to detect hydrogen peroxide

“You can actually visualise this green emission (photoluminescence) with the naked eye. You don’t need any sophisticated instruments. All you need is a simple UV (ultraviolet) light source. Since the paper disc is low-cost, biodegradable and easy to use, it could serve as a powerful tool in low-resource settings, even for testing biological fluids like blood. Detecting hydrogen peroxide efficiently is also crucial in other fields; peroxide-based explosives, for example, can be traced using hydrogen peroxide, which is sometimes used as a starting material,” said Arnab Dutta, a PhD student in the Department of Organic Chemistry and the first author of the study published in the ACS Sensors journal.

When the researchers applied this technique to randomly test five different hand sanitiser brands, they found that only three of them contained the level of hydrogen peroxide mandated by the World Health Organization – 0.125 per cent. A fourth appeared to have much lower than 0.125 per cent and one had almost no hydrogen peroxide.

“Hydrogen peroxide can be detected on a larger scale using titration and other experiments, but those are cumbersome and require training. This method is easy because of its simplicity,” said Uday Maitra, professor in the department and a senior author of the study.

Maitra’s lab has been working on developing several “sensitiser” molecules that turn on the photoluminescence of elements called lanthanides in the presence of specific chemicals or compounds. They have previously developed paper-based sensors for detecting specific antioxidants in green tea – and thereby testing its quality – as well as sensors for various enzymes.

The sensitiser molecule they designed enables a metal called terbium to emit a green light under an ultraviolet lamp. When the sensitiser is combined with a masking agent, the green light vanishes. When hydrogen peroxide is added to this combination, it unmasks the sensitiser molecule, making it glow green once again. Maitra added,“The molecule we have designed is very specifically unmasked by hydrogen peroxide.”

The team is working on cutting down the reaction time; it takes a bit longer if the concentration of hydrogen peroxide is lower. Maitra said they were also working on developing a small, portable device where the detection can be done in a more automated manner. “We are in touch with a start-up in Chennai. We have a few prototypes made with UV LEDs and a camera to generate the emission, take a photograph, and use an image processing app to quantify the amount of hydrogen peroxide,” he said.