Quantification of Melamine in Milk and Dairy Products by Liquid Chromatography after a Simple Sample Clean-Up Procedure

Abstract

In this work, a simple procedure of melamine determination in dairy products is reported. This is based first on melamine extraction from dairy products by 1% acetic acid, sonication, centrifugation and filtration by 0.45 µm filter. The proposed method has a low detection limit (0.50 mg kg−1), high accuracy (%recovery 98.9%), high precision (%RSD range 1.6–2.5%), high calibration sensitivity (19,335 (mg l−1)−1), and a wide dynamic range (1.0–50.0 mg l−1). Melamine was accurately quantified in spiked powdered milk, infant powder milk, full‐fat liquid milk, fat‐free liquid milk, local yoghurt, and local soft cheese (spiking levels 0.5, 50, and 1000 mg kg−1). The samples have variable amounts of fat (0–29%) and protein (3–23%) indicating the wide applicability of the proposed method. The %recoveries with %RSD were 78.2–103.6(2.5), 92.7–98.8(4.7), 79.3–101.5(3.8), 86.3–101.0(2.6), 78.0–89.2 (8.3), and 91.8–103.8(3.2) for soft cheese, yoghurt, powdered milk, infant powder, full‐fat liquid milk, fat‐free liquid milk, respectively.