Determination of Melamine in Liquid Milk by Ion Chromatography with UV Detection

An analytical method using ion chromatography separation coupled with UV detection was developed for the determination of melamine in liquid milk. The procedure was based on extraction of test portions with acetonitrile, cleanup on an OnGuard II RP column to remove fat and filtration through 0.22 μm nylon membrane followed by ion chromatographic analysis of the extracts, using an IonPac CS17 column and UV detection at 240 nm. The calibration curve showed good linearity in the range of 0.02-5.0 mg/L, with a correlation coefficient of 0.99995. The recoveries for melamine spiked liquid milk ranged 82% -94%. The method has the advantages of easiness and quickness, and therefore can be applied for the determination of melamine in liquid milk.