Pink paper probe exposes formaldehyde

A new test, developed by investigators in China, exposes formaldehyde quickly and colourfully wherever it may be.

Formaldehyde is a carcinogenic pollutant produced mainly by industrial activity. It also occurs naturally in plants and animals, albeit only in small quantities. The simple aldehyde can be harmful in larger concentrations, but detecting it requires specialised equipment or applying harsh acids or bases.

Weiying Lin and her team at the University of Jinan designed a simple test to detect formaldehyde in solution, air and even in living cells. The probe contains a molecule that performs a ring-closing reaction when exposed to the aldehyde and turns pink – the more formaldehyde is present, the stronger the colour.

The test found formaldehyde in solution within 10 seconds, but could also identify the compound in living human cells and in dried shiitake mushrooms. To be able to test for gaseous formaldehyde, Lin and her colleagues redesigned the test to fit on a paper strip. The strip could detect the pollutant even at low levels in a well-ventilated room.