Scientists at East China University of Science and Technology, Shanghai, have developed a rapid and sensitive color-based test that could be used to determine if food or beverages have been contaminated with low-level concentrations of phthalates, writes Russell Johnson for Chemistry World.
Phthalates can be used as plasticizers to give materials more flexibility, but ingesting them can cause hazardous hormonal imbalance. Therefore, strict rules prohibit plasticizers such as phthalates from leaching from food packaging into food or drinks or being added to foods during processing.
However, as described in the video from earlier this year (below), plasticizers have been found in instant noodle products made in China, and Taiwan’s food industry faced a scandal related to high levels of plasticizers in food.
The team showed that their test could detect levels of phthalates as low as 0.5 ppm in tea, juice, and carbonated drinks. That level surpasses the food safety limit of 1.5 ppm. Because the test doesn’t require special analytical equipment, it could be conducted during on-site inspections to food companies.
Bang-Ce Ye and his team created a test that stays red if the food or drink does not contain phthalates, and turns purple if it does. The test uses gold nanoparticles modified with uridine 5′-triphosphate to detect the phthalates.
Johnson describes how the test works:
In the presence of phthalates and Cu2+, the modified gold nanoparticles are cross-linked together with the phthalates, forming a bridge between different nanoparticles. The cross-linking reaction causes aggregation of the nanoparticles and the distinctive red-to-purple colour change.
Other researchers praised the work. Juewen Liu, an expert in bioinorganic and analytical chemistry at the University of Waterloo, Canada, told Johnson:
This is a beautiful example of combining the knowledge of coordination chemistry, supramolecular chemistry and nanoscience to solve an emerging analytical challenge.
Source: “Detecting plasticisers in drinks,” Chemistry World, 10/6/11
Source: “Plasticizers Found in Chinese-made Instant Noodles,” YouTube
Image by Like_the_Grand_Canyon, used under its Creative Commons license.
Rachel Petkewich is a freelance science writer and editor. She has worked as a research scientist in the chemical industry and spent eight years as a staff writer and editor at various science journals and magazines, including Chemical & Engineering News.