QUANTIFICATION OF MELAMINE IN MILK AND DAIRYrnPRODUCTS BY LIQUID CHROMATOGRAPHY AFTERrnA SIMPLE SAMPLE CLEAN-UP PROCEDURE

摘要

In this work, a simple procedure of melamine determination in dairy products isrnreported. This is based first on melamine extraction from dairy products by 1% aceticrnacid, sonication, centrifugation and filtration by 0.45 mm filter. The proposedrnmethod has a low detection limit (0.50mg kg~(-1)), high accuracy (%recoveryrn98.9%), high precision (%RSD range 1.6–2.5%), high calibration sensitivity (19,335rn(mg l~(-1))~(-1)), and a wide dynamic range (1.0–50.0mg l21).Melamine was accuratelyrnquantified in spiked powdered milk, infant powder milk, full-fat liquid milk, fatfreernliquid milk, local yoghurt, and local soft cheese (spiking levels 0.5, 50, and 1000rnmg kg~(-1)). The samples have variable amounts of fat (0–29%) and protein (3–23%)rnindicating the wide applicability of the proposed method. The %recoveries withrn%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),rn78.0–89.2 (8.3), and 91.8–103.8(3.2) for soft cheese, yoghurt, powdered milk, infantrnpowder, full-fat liquid milk, fat-free liquid milk, respectively.