2016.02.01PolyU Develops Fluorescent Probes for Rapid Detection of Formaldehyde in Food

The fluorescent probes developed by PolyU will appear to be fluorescent blue if the food sample contains formaldehyde. The result can be easily observed by naked eyes. The design and operation of the fluorescent probes are simple.

The Department of Applied Biology and Chemical Technology (ABCT) of The Hong Kong Polytechnic University (PolyU) has developed fluorescent probes for rapid detection of formaldehyde in food. In recent years, formaldehyde has been discovered to be illegally used in food processing for bleaching and preservation purposes, arousing health concerns by the general public. PolyU's highly selective formaldehyde rapid detection method involves only simple procedures. It can test 10 food samples on-site in one go in comparison to traditional methods which entail 30 minutes for the testing of each food sample one by one. Its cost is less than HK$30, which is 90% lower than traditional testing methods. If the food sample contains formaldehyde, under hand-held UV light, the fluorescent probes will appear to be fluorescent blue, which can be easily observed by naked eyes.

Traditional methods for formaldehyde measurement are liquid chromatography which involves chemical derivation of formaldehyde, chromatographic separation and instrumental analysis of the formaldehyde content with reference to the sample standard. However, these methods require expensive instruments, sophisticated operational skills, tedious sample preparation and time-consuming analysis. Given their low testing through-put, the testing of 10 food samples would require up to 5 hours (10 X 30 minutes), making these methods not suitable for on-site food safety inspection. In addition, the test results of formaldehyde testing kits available in the market are easily interfered by irrelevant substances. Their low selectivity and stability make them difficult to satisfy the on-site food safety inspection and high through-put needs of the industry and authorities.

Based on prior research on a chemical reaction that enables chemical coupling of 1) amine-functionalized resins, 2) formaldehyde and 3) fluorescent dyes via gold catalysis, PolyU researchers have developed fluorescent probes for rapid detection of formaldehyde in food with excellent selectivity and high stability. Firstly, researchers added pre-treated food samples, amine-functionalized resins, fluorescent dyes and gold catalysts into a container, and heated the solution at 50 oC for 1 hour. After that, organic solvents were added to wash out excessive reagents. The three-component coupling reaction will connect resin-linked sterically bulky amines and fluorescent alkynes through chemical bonding with formaldehyde in food so that the surface of the resins will give out fluorescent blue colour under hand-held UV light. One can easily detect the formaldehyde concentration by observing the brightness of the fluorescent colour by naked eyes. Not only is the design and operation of PolyU's invention simple, it does not require expensive instruments and sophisticated operational skills. It can test 10 food samples in one go, making it an ideal solution for on-site food safety inspection and front-line quality control. The research was conducted by ABCT in collaboration with Guangdong Entry-Exit Inspection and Quarantine Bureau.

The related paper has been recently published in Organic & Biomolecular Chemistry, a leading journal in Organic Chemistry. A joint PolyU-GDCIQ China patent has been filed. The research team will continue to enhance the formaldehyde rapid detection method, which include developing a new class of tunable fluorescent dyes and developing high through-put rapid detection formats.

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PolyU Pushes Food Test Forward with Fluorescent Probes for Rapid Detection of Formaldehyde in Food

In collaboration with Guangdong Entry-Exit Inspection and Quarantine Bureau, the Department of Applied Biology and Chemical Technology (ABCT) of The Hong Kong Polytechnic University (PolyU) has successfully developed fluorescent probes, which can quickly detect formaldehyde in food. It has been reported that formaldehyde is illegally used in food processing for bleaching and preservation, raising health concerns among Hong Kong people.

Concerning that traditional methods for formaldehyde measurement are less efficient, PolyU's research team has now designed a far more effective detection method involving simple procedures. On condition that the food sample contains formaldehyde, under hand-held UV light, the fluorescent probes will show fluorescent blue colour, which can be easily observed by naked eyes.

This new food test can be carried out for 10 food samples on-site in one go, while traditional methods usually take 30 minutes for each food sample one by one. The new method for food test also costs less than HK$30, which is 90% lower than traditional methods.

Based on previous research on a chemical reaction that enables chemical coupling of 1) amine-functionalized resins, 2) formaldehyde and 3) fluorescent dyes via gold catalysis, PolyU researchers developed the new fluorescent probes with excellent selectivity and high stability for rapid detection of formaldehyde in food. First, researchers put pre-treated food samples, amine-functionalized resins, fluorescent dyes and gold catalysts into a container. Then, the solution is heated at 50 oC for an hour. After that, organic solvents were added to wash out excessive reagents. The three-component coupling reaction will connect resin-linked sterically bulky amines and fluorescent alkynes through chemical bonding with formaldehyde in food, so that the surface of the resins will show fluorescent blue colour under hand-held UV light. The design and operation of this invention is not only simple, but also cost-effective. The related paper on food test has been published in Organic & Biomolecular Chemistry, a top-notch journal in Organic Chemistry. In the near future, the research team will continue to enhance the detection method, such as developing a new class of tunable fluorescent dyes, as well as high through-put rapid detection formats.

Press Contacts

Dr Man Kin Wong

Associate Professor, Department of Applied Biology and Chemical Technology

Email(852) 3400 8701
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