Use of Methanol for the Efficient Extraction and Analysis of Melamine and Cyanuric Acid Residues in Dairy Products and Pet Foods

Abstract

The recent worldwide shortage of acetonitrile has prompted the development of a new method using methanol as an alternative organic solvent in the extraction and liquid chromatographic analysis of melamine and cyanuric acid that may be present as contaminants in dairy products and pet foods. A simple extraction of melamine and cyanuric acid residues in fortified samples was successfully achieved, using a methanol-water mixture and analysis by isotopic dilution high-performance liquid chromatography-triple-quadrupole mass spectrometry (HPLC-MS/MS). A two-step centrifugation procedure was employed to remove matrix components from extracts. The separation of melamine and cyanuric acid was carried out on a Dionex Acclaim Trinity P1 column, with a methanol and ammonium acetate buffer used as the mobile phase. Excellent linearity was achieved for both the melamine and cyanuric acid calibrations. A variety of dairy products and pet foods were fortified with melamine and cyanuric acid at three levels, 1, 2.5, and 10 microg/g, producing recovery yields of 101-119% for melamine and 84-123% for cyanuric acid. The lower limit of quantification (LLOQ) of melamine was 0.03 microg/g for liquid milk and 0.05 microg/g for dry infant milk formula. The quantitative results were comparable with those derived from previous methods that have been proposed by the U.S. Food and Drug Administration for the screening of melamine and its analogues in foods.

Determination of Cyanuric Acid in Milk Powder by Anion-exchange Chromatography

“…Several methods have been reported for the analysis of CA in swimming pool water, such as gas chromatography (GC), 6 gas chromatography-mass spectrometry (GC-MS), 7 liquid chromatography (LC), 1,3,8 liquid chromatography-mass spectrometry (LC-MS) [9][10][11][12][13] and ion-pair LC. 14 There has been no report about the determination of CA by ion chromatography (IC).…”

Application of Tandem Mass Spectrometry for Analyzing Melamine

“…Acetonitrile has the characteristics of miscibility with water, low viscosity and results in protein denaturation which is useful in food or feed preparation to eliminate protein in the sample solution. Some studies have also reported using 30-50% methanol to reduce the amount of acetonitrile combined with sonication or two step centrifugation to extract the MEL in liquid formula, dry powder or pet foods (Tran et al, 2010;Vendatasami & Sowa Jr 2010). In addition, the non-polar solvents dichloromethane and hexane are used in lipid-lipid extraction to reduce lipid effects in highfat bio-samples, such as animal-derived food or bakery goods.…”

A 100% Water Mobile Phase HPLC-PDA Analysis of Meamine and Related Analogues

“…The optimal harmonized method must be easyto-use, economical in time and cost, and must cause no harm to the environment and analyst. For determining either MEL alone or with related analogues, previous HPLC techniques combined with UV [6], photo-diode array detector (PDA) [7], and LC-MS/ MS [8][9][10][11] have been reported. The US Food and Drug Administration issued new methods for the analysis of melamine in liquid formula, based on LC-MS/MS detection [12].…”