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Gazi University Journal of Science GU J Sci 29(3):549-558 (2016) The Determination of Ammeline by Differential Pulse Polarography /Application to Milk Zehra Yazar AYDIN1, Ümmihan T. YILMAZ2, 1Department of Nanotechnology and Nanomedicine, Hacettepe University, Ankara, Turkey 2Department of Chemistry, Gazi University, Polatli Science and Art Faculty,06900, Ankara, Turkey Received:01/04/2016 Accepted: 23/06/2016 ABSTRACT An electrochemical approach has been proposed for the determination of ammeline. Electrochemical behavior of ammeline was investigated by differential pulse polarography and cyclic voltammetry in a Britton–Robinson buffer. Optimum conditions for the analytical determination were found to be pH 9.5 at a reduction potential of –30 mV. The calibration graph was linear in the concentration range of ammeline from 0,5 μM - 39,65 μM (0.06 µg mL-1 – 4.76 µg mL-1) with a correlation coefficient of 0.998. Based on this use and under optimized conditions, with the DPP method for ammeline analysis had detection of limit (LOD) and the limit of quantification (LOQ) were obtained as 0.15 µM and 0.5 µM (0.02 µg mL-1 - 0.06 µg mL-1), respectively. This offered method has been used for the determination of ammeline in spiked milk. The result demonstrated that this method is a simple, rapid, sensitive, stable and low-cost method for ammeline detection. Keywords: ammeline, determination, polarography, milk, cyclic voltammetry 1. INTRODUCTION formaldehyde resins (AMFR). Melamine-based resins represent an important class of aminoplastic resins and Ammeline (4,6-Diamino-2-hydroxy-1,3,5-triazine) is a there are most applications as wood adhesives. AMFR product of the degradation of s-triazine herbicides. systems containing from 5-10% ammeline are more Ammeline gives the alkaline hydrolysis of melamine [1]. flexible than MFR resins and exhibit different adhesion There are various uses of ammeline. Ammeline is used properties than MFR resins [3]. The aqueous ozone in lubricating greases [2] the properties of ammeline treatment of atrazine [2-chloro-4-(ethylamino)-6- greases, including their thermo-oxidative stability (isopropylamino)-s-triazine] in the presence of hydrogen (TOS), have been studied. It was determined the peroxide was reinvestigated using a new tandem solid- influence of the ammeline concentration on the TOS. phase extraction procedure. In the experimental Another use of is Ammeline-melamine- conditions ammeline was found as the major end-product (20% at pH 8) [4]. Corresponding author, e-mail: [email protected] 550 GU J Sci, 29(3):549-558 (2016) / Zehra Yazar AYDIN, Ümmihan T. YILMAZ In March 2007, the illness and deaths of cats and dogs that the hydroxytriazines as the ammeline are less toxic were reported to the United States FDA [5] (Food and than the chlorotriazines as the atrazine. Drug Administration). The FDA’s investigation revealed that they had consumed melamine-contaminated pet Testing of the wheat glutens showed they contained food. This incidence caused a dozen deaths and hundreds significant levels of melamine and/or several related of cases of kidney-related illness to cats and dogs, and compounds including cyanuric acid, ammeline, and led to the largest pet food recall in FDA history. Further ammelide [12]. These compounds are structurally investigation found that the melamine-tainted pet foods similar, containing a 1,3,5-triazine ring (see Scheme 1). were also contaminated with structurally similar Quantitative analysis was needed as a partial basis for compounds such as cyanuric acid, ammeline and health hazard evaluations, to understand and track the ammelide. It was revealed that some ingredients used to sources of the problem, and to help assess cross make pet food, such as wheat gluten and rice protein, had contamination in the manufacturing chain. been intentionally adulterated with melamine and related Consequently, there has been growing concern about the compounds. It is assumed that these nitrogen-rich significance and toxicity of melamine and analogues; this chemicals were added to make the final product appear fact encouraged the development of methods for its trace to be protein rich, resulting in higher commercial value determination in various sample materials. [2]. Thousands of pigs died after being fed diets containing melamine at 3026 mg/kg, ammeline at 958 mg/kg and cyanuric acid at 69 031 mg/kg [6] Sheep given ammeline or ammelide with various concentrations of melamine developed crystalluria and renal failure and died [7]. Data from experimental animals and pets have shown that co-exposure, in particular to melamine and analogues, results in renal crystal formation and subsequent kidney damage. Currently, there are insufficient data on which to develop a hazard characterization for these combined exposure scenarios, Scheme 1. Structure of ammeline but it is anticipated that they would be more toxic than separate exposures. Chinese infant formula reportedly contained levels of cyanuric acid, ammeline and ammelide that were only about 0.1% of the melamine Chromatographic methods have been usually used for levels. They were also much lower than levels present in ammeline detection. A variety of chromatographic contaminated wheat gluten and rice protein concentrate detection methods, including high performance liquid ingredients that were used in the production of pet foods chromatography [13], development of a high during the 2007 melamine contamination incident in the performance liquid chromatography method and a liquid USA, Canada and South Africa [8] This was confirmed chromatography–tandem mass spectrometry method by [9] who conducted a rat study that tested ingestion of with pressurized liquid extraction for simultaneous melamine alone, ammeline or ammelide alone (both quantification and confirmation of cyromazine, analogs of melamine), a mixture of melamine and melamine and its metabolites in foods of animal origin cyanuric acid and a mixture of all four compounds. [14-16]. Micellar electro kinetic chromatography Neither ammeline nor ammelide alone produced any (MEKC) [17] liquid chromatography-tandem mass renal effects, but the mixtures produced significant renal spectrometry [18, 19] hydrophilic interaction liquid damage and crystals in nephrons. Analysis confirmed the chromatography [20] Matrix-assisted laser desorption presence of melamine and cyanuric acid in the kidney ionization/time-of-flight (MALDI/TOF) mass [8]. These human data are different from what has been spectrometry [21] and isotope dilution gas described for the outbreaks in pets in 2004 and 2007. chromatography-mass spectrometry (ID-GC-MS) [22] From all data reported to date, infants were exposed are the preferred methods of choice for ammeline primarily to melamine alone or to very low levels of analysis. Ammeline and ammelide are also produced cyanuric acid when melamine was present at very high during the production of melamine as by-products and concentrations, whereas pets were exposed to melamine their HPCEC analysis has been reported by Debowski and cyanuric acid and possibly to ammeline and and Wilde [23]. ammelide. Affected infants appear to have developed Only a few studies are available for the electrochemical stones primarily in the urinary tract, which sometimes led investigation of melamine in general [24-26] and to the to obstructive renal failure [10]. Pets, however, exposed best of our knowledge, no publications dealing with the to the combination of melamine and cyanuric acid, electroanalytical or polarographic determination of formed crystals in renal tubules, developing an intra- ammeline have appeared so far. Compared to tubular obstructive nephropathy. Pets developed acute chromatography, voltammetric techniques have several renal failure within 2 days of exposure in severe advantages such as low cost and possibility of analysis exposures, whereas most infants with stones reportedly without the need of pre-treatments, as well as the short did not have overt clinical symptoms [11]. Regarding the time required for the analysis [27]. toxicity, Stratton [4] determined the toxic effects of atrazine and four of its degradation products. Point out The purpose of the present work is to examine the polarographic determination of ammeline, find out GU J Sci, 29(3): 29(3):549-558 (2016) / Zehra Yazar AYDIN, Ümmihan T. YILMAZ 551 optimum analysis conditions and apply the method for Contaminated mercury was cleaned by passing it -1 the determination of melamine in milk. Also, successively through dilute HNO3 (3.0 mole L ) and electrochemical behaviors of melamine are investigated water columns in the form of fine droplets by using a with cyclic voltammetry. platinum sieve. The collected mercury was dried between sheets of filter paper. Whether there is of 2. EXPERIMENTAL impurities before use in mercury was checked by DPP. 2.1. Reagent Ten milliliters (10 mL) of supporting electrolyte solution The mercury used in the dropping mercury electrode was was put into the polarographic cell. The supporting purchased from Merck (Darmstadt, Germany). electrolyte was used Britton-Robinson (B-R) buffer Ammeline was purchased from Sigma. Other all solution. NaOH and HCl was used to adjust pH. At the chemicals used analytical grade, was purchased from start of all experiments, pure N2 gas about 5 min was Merck and Sigma. Working standard solutions were passed from all of the prepared solutions for extract prepared by dilution of stock solution with water. oxygen. All the experiments were done at room Distilled