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Researcher invents easy-to-use formalin test kit

A Mahidol Universtiy researcher has developed simple but ingenious testing technology that would come in handy for consumers to detect formalin contamination in foods.

Applying chemistry science to food testing methods, Assoc. Prof. Dr. Palangpon Kongseree, lecturer at Department of Chemistry, Faculty of Science, has come up with a formaldehyde test kit that gives quick, clearly visible results enabling users to learn right away whether foods or beverages contain harmful amounts of this much-abused substance.

The test kit is inexpensive and convenient for on-site test. Testing procedures are also simple. It requires no sophisticated equipment, sample preparation or special skills.

Though highly specific for formaldehyde, this device only reacts when the substance are present at levels considered hazardous to health.

When this happens, the test strip changes from colorless to pink-red and glows under green light. It produces no color changes though when formaldehyde contents are at levels occurring naturally.

Formalin contamination in foods has been a major problem for the food industry in Thailand. Formalin, a solution of formaldehyde 37% by mass in water, is used as an embalming agent to temporarily preserve corpses.

However, the chemical has been widely misused to preserve freshness of vegetables, fruits meats and seafood. High concentrations of formaldehyde in foods are toxic and harmful to health.

Formaldehyde with concentrations up to 100 ppm can be found naturally in different types of foods, according to Dr. Palangpon, who is also a researcher at Center for Excellence in Protein Structure and Function. .

While human body can get rid of formaldehyde at certain levels, the doses of formalin used as preservatives usually exceed the body's capacity to purge it and its residue in the body could pose danger to consumers' health.

Thus the test kit is designed to detect formaldehyde contamination when its concentrations are above a threshold of safety, or greater than 1,000 ppm.

Since formaldehyde is electron-poor, it wants to react with electron-rich substances. Taking advantage of this fact, the researcher uses a reagent that—when reacts with formaldehyde—produces a red-color substance to alert the user to the danger.

"What is challenging is that this chemical reaction must be fast and able to occur in water since most samples have high content of water.

"Most important, it must not react with formaldehyde at levels found naturally," said Dr.Palangpon, who received 2013 Invention Award (Chemical Sciences and Pharmacy Section) from National Research Commission for the project.

This innovative testing technique has addressed the drawbacks of purpald test, which has been in use for more than forty years. The latter needs to be performed under strongly alkaline conditions, has low specificity and unstable color development and cannot be used in colored samples.

Because formaldehyde is colorless and testing is difficult, people are hardly aware or able to detect formalin contamination in their foods.

Although formaldehyde can be diluted or dissolved partially by washing and heat, for safety or when suspecting formalin contamination, consumers should wash fresh vegetables and fruits properly as follows:

Add 20-30 potassium permanganate flakes to 4-5 liters of water. Then soak the foods in the solution. Formaldehyde will react with potassium permanganate and turn into formic acid, which is soluble in water and can be washed away.


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