Occurrence of Melamine and Cyanuric Acid in Milk, Baby Food, and Protein Supplements Marketed in Croatia

The aim of this study is to investigate the occurrence of melamine and cyanuric acid in milk, baby food, and protein supplements collected in Croatia. A total of 56 samples were collected during 2022 and 2023 from retail stores in Zagreb, Croatia. Sample preparation involved acetonitrile extraction, followed by analysis using ultra-high-performance liquid chromatography coupled with tandem mass spectrometry (UHPLC-MS/MS). Cyanuric acid concentrations above the limit of quantification (LOQ) were found in five milk samples (33.3% detection frequency), with a range from 0.26 to 0.39 mg/kg and a mean concentration of 0.31 mg/kg. In protein supplements, melamine was detected above the LOQ in six samples (23% detection frequency), with a mean concentration of 0.30 mg/kg and concentrations ranging from 0.20 to 0.57 mg/kg. No concentrations above the LOQ were found in baby food samples. All detected values were below the EU maximum limits (2.5 mg/kg for general food and 1.0 mg/kg for baby food). The accuracy and reliability of the method were verified using certified reference material. This is the first study to confirm the presence of melamine and cyanuric acid in protein supplements and milk on the Croatian market. The detected levels do not indicate a potential health risk to consumers.