Melamine and Cyanuric Acid in Foodstuffs and Pet Food: Method Validation and Sample Screening

Abstract

Hazardous levels of melamine in food and feed products have been of great concern after the outbreak of contamination reported in Chinese commodities in 2008. Despite the existence of several analytical methods for melamine (MEL) detection in food, few provide a full validation data set, especially when MEL and cyanuric acid (CYA) are analyzed simultaneously. The aim of this study was to validate an analytical methodology for MEL and CYA analysis in foodstuffs by GC-MS after trimethylsilylation with N,O-bis(trimethylsilyl)trifluoroacetamide. Linearity was obtained in the range of 0.4 to 800 mg/kg for both compounds, with limits of detection (LODs) of 0.15 and 0.05 mg/kg for MEL and CYA, respectively. Screening in 20 food products [3 soya milk powder, 1 baby milk powder, 3 soya powder, 13 diversified cookies and biscuits (8 from China and 2 from Portugal), and 3 dog food) revealed MEL incidence in 55% of the cases, with a maximum concentration of 3.4 mg/kg. CYA was not detected in all samples.

Keywords:

• Cyanuric acid
• Food stuffs
• GC/MS
• Melamine
• Method validation
• Pet food

Acknowledgments

This paper is part of a special issue organized by Dr. Nikolaos Thomaidis and Dr. Antony C. Calokerinos from research presented at the Aegean Analytical Chemistry Days Conference in Lesvos, Greece on 29 September–3 October 2010.

The authors wish to thank Fundação para a Ciência e a Tecnologia (FCT - Portugal) for Project PTDC/AGR-CFL/73156/2006. Fátima Ferreira and Serafim Pereira (DEQ-FEUP) are thanked for their help in the analytical protocol.

Notes

AMD, ammelide; AMN, ammeline; I.S., internal standard.

*The final volume is 600 µL since 100 µL of internal standard were added in each experiment.

*Limit of detection (LOD) for melamine is 0.15 mg/kg.

SM, soya milk powder; MP, milk powder; SP, soya powder; CB, cookies and biscuits; DF, dog food.