ARS | Publication request: Development of an immunochromatographic strip test for rapid detection of melamine in raw milk, milk products, and animal feed

Submitted to: Journal of Agriculture and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 28, 2011
Publication Date: May 6, 2011
Citation: Li, X., Lui, P., Tang, S., Beier, R.C., Wu, X., Yang, L., Li, Y., Xiao, X. 2011. Development of an immunochromatographic strip test for rapid detection of melamine in raw milk, milk products, and animal feed. Journal of Agricultural and Food Chemistry. 59:6064-6070.

Interpretive Summary: In the last few years, melamine has been used intentionally and illegally in food and food-related products to provide a false indication of increased protein content during testing procedures for the food item. High or continuous exposure to melamine can cause renal stones and urinary bladder tumors. Melamine contaminated food led to kidney failure in dogs and cats in 2004, and resulted in illnesses and deaths of pets in the United States during 2007. In 2008, milk powder contaminated with melamine in China led to infant hospitalizations and deaths. In this study, an immunogold chromatographic strip test was developed to test for melamine onsite. The strip test is based on a monoclonal antibody that specifically binds melamine. Antibodies are substances that are produced by the immune system in response to foreign substances which enter the body. Once the antibodies to a foreign substance are isolated, they can be used in a method to detect the presence of that foreign substance. The melamine strip test is similar to the common pregnancy test, and is as simple to use. The melamine strip test was evaluated for raw milk, milk products, and animal feed samples. The limit of detection was 2 µg/mL (or 2 µg/g) for milk drinks, yogurt, condensed milk, cheese, and animal feed and 1 µg/g for milk powder. Sample pretreatment was simple and rapid, and the results can be obtained within 3–10 min. The results demonstrate that the developed method is suitable for the onsite determination of melamine in a large number of samples.

Technical Abstract: A simple, rapid and sensitive immunogold chromatographic strip test based on a monoclonal antibody was developed for the detection of melamine (MEL) residues in raw milk, milk products and animal feed. The limit of detection was estimated to be 0.05 µg/mL in raw milk, since the detection test line on the strip test completely disappeared at this concentration. The limit of detection was 2 µg/mL (or 2 µg/g) for milk drinks, yoghourt, condensed milk, cheese, and animal feed and 1 µg/g for milk powder. Sample pretreatment was simple and rapid, and the results can be obtained within 3–10 min. A parallel analysis of MEL in 52 blind raw milk samples conducted by gas chromatography–mass spectrometry showed comparable results to those obtained from the strip test. The results demonstrate that the developed method is suitable for the onsite determination of MEL residues in a large number of samples.