New Toxic Chemical Detection System Created For Identifying Melamine in Milk

Scientists from Gazi University recently created a new analysis system for detecting melamine, a toxic chemical, in milk samples. Their work was published in Spectrochimica Acta, Part A: Molecular and Biomolecular Spectroscopy (1).

Natural whole milk | Image Credit: © iprachenko - stock.adobe.com

Melamine is a nitrogen-heavy chemical commonly used in plastics, coatings, kitchenware, and more. However, MEL can also be illegally used in food and feed products to increase protein content, which can be problematic because of potentially causing tissue injury and bladder cancer. Because of this concern, there is a need for rapid, low-cost, and sensitive methods for detecting trace MEL levels. In their study, the research team demonstrated the utility of a new phosphorescence sensor based on inorganic surface molecularly imprinted polymers and manganese-doped zinc sulfur (ZnS) quantum dots (QDs).

Quantum dots (QDs) are nanostructured semiconductors that have been used in fluorescence detection studies. Specifically, researchers have been looking at the phosphorescent properties of QDs, and how room temperature phosphorescence (RTP) QDs can be used as phosphorescence sensors. Scientists believe RTP has the capability to reduce interferences from autofluorescence and scattering light from the studied matrices. RTP allows for higher selectivity, and studies on RTP are usually conducted with solid supports or in liquid media in the presence of deoxidants and other inducers. Because the researchers used the Mn-doped ZnS QDs based RTP detection technique, no deoxidant was required.

For this experiment, the scientists used a novel room temperature phosphorescence sensor (IMIPs-ZnS QDs RTP sensor) based on inorganic surface molecularly imprinted polymers and Mn-doped ZnS QDs. The surface of the Mn-ZnS Qds were modified with 3-(mercaptopropyl) trimethoxy silane (MPTS), with MEL, 3-aminopropyltriethoxysilane (APTES) and tetraethoxysilane (TEOS) being used as the template (target molecule), functional monomer, and cross-linker, respectively. As such, the IMIPs-ZnS QDs RTP sensor was applied for detecting MEL residue in milk samples, yielding promising results in the process. Recovery values ranged from 88.62%–90.22%, with high precision values (0.57–0.92% RSD).

Overall, the findings showed the developed IMIPs-ZnS QDs RTP sensor exhibiting high sensitivity and selectivity towards the MEL in milk samples containing potentially high levels of interfering compounds. With this experiment, detecting toxic chemicals in milk samples is now a simpler process, though there is still more work to be done.

Reference

(1) Yilmaz, H.; Ertaş, N.; Basan, H. Development of a New Phosphorescence Sensor Based on Surface Molecularly Imprinted Mn-Doped ZnS Quantum Dots for Detection of Melamine in Milk Products. Spectrochim. Acta A Mol. Biomol. Spectrosc. 2024, 309, 123818. DOI: https://doi.org/10.1016/j.saa.2023.123818