Voltamperometric Discrimination of Urea and Melamine Adulterated Skimmed Milk Powder

Abstract

Nitrogen compounds like urea and melamine are known to be commonly usedfor milk adulteration resulting in undesired intoxication; a well-known example is theChinese episode occurred in 2008. The development of a rapid, reliable and economic testis of relevance in order to improve adulterated milk identification. Cyclic voltammetrystudies using an Au working electrode were performed on adulterated and non-adulteratedmilk samples from different independent manufacturers. Voltammetric data and their firstderivative were subjected to functional principal component analysis (f-PCA) and correctlyclassified by the KNN classifier. The adulterated and non-adulterated milk samples showedsignificant differences. Best results of prediction were obtained with first derivative data.Detection limits in milk samples adulterated with 1% of its total nitrogen derived frommelamine or urea were as low as 85.0 mg/L and 121.4 mg/L, respectively. We presentthis method as a fast and robust screening method for milk adulteration analysis andprevention of food intoxication.