Screening and determination of melamine residues in tissue and body fluid samples

Melamine is a chemical product that was sporadically mixed into animal feeds to boost protein content. Excessive melamine in animal feed can induce renal failure and even death in animals. The residue of melamine in edible animal products also threatens human health. Currently, there is no real-time and high throughput method to detect residual melamine in animal tissues. Successful development of such methods is very important for fast and on-site screening of melamine residue in animal tissues to eliminate the potential threat to human health. Here we demonstrate the detection of residual melamine from swine and chicken tissues and body fluids using indirect competitive enzyme-linked immunosorbent assay (ELISA) method. A detection sensitivity of 0.5 μg mL−1 and a limit of detection of 0.05 μg mL−1 were achieved with this method. A gas chromatography–mass spectrometry (GC–MS) method was also developed to act as a confirmatory and quantitative procedure for the ELISA results. The limits of quantitation (LOQ) of were 0.01 μg g−1 and 0.005 μg mL−1 for tissues and body fluids, respectively. The two methods showed good agreement (r2 > 0.992). The method developed was performed on samples of tissues from chickens fed with melamine-spiked feed.