Determination of Melamine and Cyanuric acid in some food products using Liquid Chromatography with Tandem Mass Spectrometry

Abstract

Simple, rapid and sensitive method for determination of melamine and cyanuric acid in baby milk and liquid milk was developed using LC-MS/MS. Extraction with 100 mM ammonium acetate buffer at pH 4 was selected based on the resulted accepted recovery and precision. The Sample was extracted with ammonium acetate buffer, followed by centrifugation; the supernatant was diluted with acetonitrile, and re-centrifuged. The extract was filtered and injected into LC-MS/MS system. Different parameters (e.g. declusting potential and collision energy) were optimized using Sciex 4000 QT in electron spray ionization positive and negative modes. Due to LC-MS/MS signal suppression/enhancement, determination of melamine and cyanuric acid was based on matrix matched standard calculation. The method was validated at different fortification levels for liquid milk and baby milk. Recovery values of melamine ranged from 72% to 97% with RSD% less than 5%. Recovery values for cyanuric acid ranged from 83 and 112% with RSD% less than 8.6%. Limit of quantification of 0.05 mg/kg and 0.01 mg/kg was obtained for melamine for baby milk and liquid milk, respectively. For Cyanuric acid Limit of quantifications were 0. 5 mg/kg, 0.1 mg/kg for baby milk and liquid milk, respectively. The method performance was confirmed by participating in different proficiency tests from FAPAS, UK and EURL-SRM, Germany, and accepted Z-scores were obtained. Key words:Melamine, Cyanuric acid, Baby milk, LC-MS/MS.