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reportedly been affected by adulterated formula. Over 50,000 were hospitalized, and at least 6 died. Reports of Melamine contaminated foods manufactured in the USA and other countries occurred in the subsequent months (Ingelfinger, J. R. (2008). Melamine and the global implications of food contamination. New England Journal of Medicine, 359, 2745–2748.).
These Melamine contamination incidents prompted the US Food and Drug Administration (FDA), the European Community and other countries and regions to establish the criteria of Maximum Residue Limits (MRLs) for Melamine in various everyday products. Today’s methods for reliable detection of Melamine in milk and accurate analysis of its concentration require several purification steps followed by HPLC analysis and are time consuming and costly.
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Melamine, (2,4,6-triamino-s-triazin), is a common raw ingredient for the manufacture of plastics, but it is frequently misused by adding it to food to raise the nitrogen content, thereby giving the false impression of a high protein content. Although Melamine has low toxicity, it may lead (especially in children) to kidney stones, eventual renal failure, and ultimately death, when it forms an insoluble compound with the analogue cyanuric acid. In 2007, Melamine was found in pet-food products, and led to kidney toxicity in dogs and cats in the USA. Later, Melamine contamination was found in milk-based products for infants in China. Because China is a major exporter of milk products and ingredients, the events created a widespread food-safety scare. More than 294,000 children in China have B
Forensics, Food Safety and Quality, Pharmaceuticals, Biotechnology, Plastics and polymers, Cell Biologist, Biology, Chemicals, Academic research and teaching labs, Enviromental Analysis
Although alternative methods for melamine detection in milk (including those by Raman spectroscopy, both regular, and SERS) have been recently developed, they also required either a preliminary melamine extraction procedure (using either SPE columns, HPLC, or differential centrifugation, ex.: M. Lin et al., (2008). Detection of Melamine in Gluten, Chicken Feed, and Processed Foods Using Surface Enhanced Raman Spectroscopy and HPLC. Journal of Food Ccience, 73: 129-134), and/or specially synthesized and rather expensive “cylindrical” or “imprinted polymer” SERS particles (P. Rajapandiyan et al., (2015). Rapid detection of melamine in milk liquid and powder by surface enhanced Raman scattering substrate array. Food Control 56: 155e160; Yaxi Hu et al., (2015) Detection of melamine in milk using molecularly imprinted polymers–surface enhanced Raman spectroscopy. Food Chemistry 176: 123–129).
Digilab recently partnered with companies developing SERS substrate requesting creating substrate(s) specific to melamine. This opens a possibility of melamine detection without a need to extract the chemical from the milk sample. The contaminated milk samples thus can be directly placed into wells of 96-well plate and scanned by Identity Raman plate reader to obtain clear “yes”-“no” result. Identification of melamine with this method is going to be fast and inexpensive. As an example of such procedures, the image below illustrates detection of melamine in raw milk samples with such a SERS substrate recently obtained by one of our partners. There is clear dependency of the peak intensity of the melamine concentration in milk which opens a possibility to not only detect melamine in contaminated milk, but also determine/estimate its concentration in the sample.
Digilab has combined recent technology advancements in the miniaturization of spectrometers, data storage, laser technology, robotics and automation and developed Digilab Identity Raman Plate Reader, enabling high throughput sample measurement into microtiter plates or slides for many research applications and industries. To see more on the Identity Raman plate reader, click here.