Determination of melamine in milk by fluorescence spectroscopy and second-order calibration

• Published in: Food chemistry 2021-12, Vol.364, p.130407-130407, Article 130407
• Main Authors: Barreto, Matheus C., Braga, Raíssa G., Lemos, Sherlan G., Fragoso, Wallace D.
• Format: Article
• Language: English
• Subjects: Adulterated milk; Fluorescence spectroscopy; Melamine; PARAFAC; Second-order calibration; U-PLS/RBL
• ISSN: 0308-8146; 1873-7072
• DOI: 10.1016/j.foodchem.2021.130407

•EEM spectroscopy can be used with second-order methods to determine melamine in milk.•A single step environmentally friendly clean-up can be used.•Melamine was detected in adulterated milks starting at 2% of fraudulent dilution. Melamine is a compound commonly used in the manufacturing of plastic and flame retardant products, but due to its solubility on water and high nitrogen content, it is also used to adulterate milk to mask adulteration by dilution in protein content tests. This work proposes a quick method using excitation-emission matrix (EEM) fluorescence spectroscopy and second-order calibration methods (PARAFAC and U-PLS/RBL) for the identification and quantification of melamine in milk. The proposed method uses a single clean-up step with acetic acid, resulting in a quick, low-cost, and environmentally friendly procedure, in agreement with green chemistry principles. Both PARAFAC and U-PLS/RBL were capable of detecting melamine in milk above 120.6 and 146.5 ppm respectively, adequate for adulterations above 2% in volume, with RMSEPs of 68.6 and 81.9 ppm, respectively.