More on melamine extraction in dairy and biological samples.
Recently, a great deal of interest has been seen in the analysis of melamine and its metabolites. Melamine (structure shown) is traditionally used in making plastics; however, its low cost and high nitrogen content has led to exploitation in various sections of the food industry, most notably involving dairy products. The standard test for estimating protein content is based on measurement of nitrogen levels, therefore, addition of melamine to sub standard or diluted milk results in the protein levels appearing higher. Sustained melamine exposure can result in kidney stones and renal failure, with the young being most susceptible.Many methods have been shown for the analysis of melamine. They often use a mixed-mode cation exchange phase when sample preparation is necessary to reach low quantification values. However, the vast array of complex matrices in which melamine must be detected, combined with the sensitivityoften required, has led to the development of a product and methodology that provides even greater clean-up without additional steps or cost. This article describes the use of a new mixed-mode resin based SPE column, EVOLUTE CX for a more efficient extraction of melamine from a range of complex samples, including both dairy products and biological fluids. A range of extraction conditions were investigated, to identify the optimum procedure for extraction of this small, polar basic molecule in terms of both analyte recovery and extract cleanliness in LC–MS–MS.