Application of First Order Derivative UV Spectrophotometry Coupled with H-Point Standard Addition to the Simultaneous De
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Application of First Order Derivative UV Spectrophotometry Coupled with H-Point Standard Addition to the Simultaneous Determination of Melamine and Dicyandiamide in Milk Huayu Zou & Kailin Xu & Yuyan Feng & Bing Liang
Received: 7 May 2014 / Accepted: 3 July 2014 # Springer Science+Business Media New York 2014
Abstract A simple and rapid method for simultaneous determination of melamine and dicyandiamide in milk was developed, in which first order derivative UV spectrophotometry was coupled with the improved H-point standard addition proposed in our previous paper for melamine and with Kratio-H-point standard addition for dicyandiamide, respectively. Dicyandiamide and melamine did not influence with each other determination. The method was applied successfully to the determination of melamine and dicyandiamide in three kinds of milk samples, including two kinds of milk powder and one kind of liquid milk. The relative standard deviation (n= 3) for the determination of melamine was in the range of 4.37∼6.05 % with recoveries of 94.3∼110.6 %, for dicyandiamide was in the range of 0.12∼3.44 % with recoveries of 94.27∼110.6 %. The proposed method can be applied to samples containing melamine higher than 0.69 mg kg−1 in milk powder and 0.15 mg L−1 in liquid milk, and dicyandiamide higher than 0.011 mg kg−1 in milk powder and 0.013 mg L−1 in liquid milk. Furthermore, it is organic solvents-free and less laborious. Keywords Melamine . Dicyandiamide . Milk . Simultaneous determination . HPSAM
Introduction Melamine, due to its very high proportion of nitrogen, has been added illegally to foods and feed to increase the measured protein content (Tsai et al. 2010). But the chronic administration of high concentration of melamine can induce H. Zou : K. Xu : Y. Feng : B. Liang (*) College of Chemical Engineering, Sichuan University, Chengdu 610065, China e-mail: [email protected]
renal pathology and even death, especially in babies and children (Guan et al. 2009). In order to guarantee the safety of food and protect the health of humans, many countries and regions such as the USA, the European Union (EU), and Australia have established a tolerance level for melamine and its analog in food to be 2.5 mg/kg. In China, the tolerance level for melamine has been set to 1 mg/kg for infant formula and 2.5 mg/kg for milk, milk products, and food containing >15 % milk. In July 2, 2012, the 35th Session of the Codex Alimentarius Commission reviewed the melamine limits in liquid infant formulas and adopted the melamine limit of 0.15 mg/kg (WHO 2009). New Zealand’s milk and milk products are famous around the world. In January 2013, it was reported that New Zealand’s milk and milk products were found to contain dicyandiamide (DCD) due to the use of fertilizers containing DCD as a nitrification inhibitor in some pastures to promote the growth of grass. The New Zealand government ordered a ban on the sale of milk products containing DCD. Afterwards, DCD was added by the US Food and Drug Administration (FDA) to the list of materials that ne
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