Visual Detection and Determination of Melamine Using Synthetic Dyes

We have used spectroscopic technique for the detection of melamine. The effect of melamine on the colour as well as the pH of bromophenol, methyl red and alizarin red dye solutions was examined at different mole ratios. It is found that we observe color transition and the absorption maxima for bromophenol were at 598？nm, while for methyl red, and alizarin red-S dye they are at 520？nm and 423？nm, respectively. We observe an increase in the absorption intensities at 598？nm with increase in the concentration of melamine in bromophenol blue dye. The absorption intensities at 520？nm decreases and new peak at 420？nm emerges in methyl red dye-melamine mixture. While the absorption intensities at 420？nm decreases and 520？nm peak emerges in alizarin red S dye-melamine at higher mole ratios. The results indicate that we can choose the appropriate dye of suitable range to detect the concentration of melamine from 3 to 206？mg？dm？3. The results demonstrate possible use of the simple method for the qualitative and quantitative detection of melamine in adulterated food samples. 1. Introduction Melamine is a weak organic base with the chemical formula C3N6H6 which contains 67% of nitrogen mass. Melamine in combination with formaldehyde produces melamine resin and has been widely used as fire retardant for the release of nitrogen when burned [1, 2]. Melamine foam has also been employed as a colourant, superplasticizer, polymeric cleansing product, insulator and so forth [3]. In early 1950 and 1960s, melamine was used as nonprotein food source for ruminants and also as source of nitrogen for food crops [4]. Development of dairy industries in last few decades has resulted in the promotion of adulterating the food products across the world with an ulterior motive to gain higher profits [5]. Several thousand people die every year due to the consumption of adulterated food. One of the classic examples is the sudden death of infants and pets across the world in 2007 and 2008 due to the adulteration of infant milk powder and pet food with melamine [6]. One of the most widely used methods to detect the protein content in the samples is by using Kjeldahl and Dumas test. In this test, nitrogen content will be estimated to obtain information about the protein content [7]. Melamine contains higher percentage of nitrogen content and this promoted the food industries to adulterate the food products with melamine illegally to enhance the apparent nitrogen content in the milk powder during the estimation of protein levels [8]. Alternative techniques used for the detection of melamine