Analysis of Dicyandiamide and Melamine in Milk Powders by LC/MS/MS Method

Introduction

Melamine was found to be used as a protein-rich adulterant first in pet-food in 2007, and then in infant formula in 2008 in China. The outbreak of the melamine scandal that killed many dogs and cats as well as led to death of six infants and illness of many had caused panic in publics and great concerns in food safety worldwide. Melamine was added into raw milk because of its high nitrogen content (66%) and the limitation of the Kjeldahl method for determination of protein level indirectly by measuring the nitrogen content. In fact, in addition to melamine and its analogues (cyanuric acid etc), a number of other nitrogen-rich compounds was reported also to be potentially used as protein-rich adulterants, including amidinourea, biuret, cyromazine, dicyandiamide, triuret and urea. Recently, low levels of dicyandiamide (DCD) residues were found in milk products from New Zealand [3-4]. Instead of addition directly, the DCD present in the milk products was explained to be due to that cows eating the grass “contaminated by DCD” may produce milk containing traces of DCD residues. Dicyandiamide is a toxic agrichemical compound and could be used to promote the growth of pastures where cows graze. We report here a LC/MS/MS method for sensitive detection and quantification of both dicyandiamide (DCD) and melamine in infant milk powder samples.

January 28, 2014 GMT