Abstract
Color is an essential part of the characteristics of food and can affect the products’ success in the food market. Since the visual aspect of a product can be an important factor in a consumer’s decision, artificial color additives are widely used to enhance the appearance of food and beverages to stimulate appetite. Considering the advantages from synthetic dyes including better stability, brightness, lower cost and availability of a range of colors are frequently chosen over natural dyes by food industries. However, in recent years, consumption of synthetic colorants are subject to stringent regulation because of concerns about the potential health risks in public health. As a family compounds in the class of azo dyes, mostly Sudan dyes have been used for coloring chili products by illegal manufacturer due to their strong color giving nature and low cost. Even, Sudan dyes are categorized as Class 3 carcinogens by the International Agency for Research on Cancer (IARC) and, therefore, are illegal as food additives according to both the FDA and the EU. The EU has set detection limits at 0.5-1 mg/kg, and any food material containing more than the limit should be withdrawn from the market. Here, we synthesized a kind of magnetic strong anion exchange adsorbents for the first time, developed sample pretreatment, used UPLC to rapid separate four Sudan Dyes. In this work, firstly magnetic nanoparticles were synthesized using chemical coprecipitation method and followed by coating with polymers of Tetraethoxysilane (TEOS) and N-trimethoxysilylpropyl-N,N,N- trimethylammonium chloride (TMSPTMA) through polymerization process to obtain magnetic strong anion exchange adsorbent (MSAEA). Further the synthesized material was characterized using Z-potential, FT-IR, SEM and SQUID. Sudan dyes contain hydroxyl groups which can be ionized under certain pH range and formed anions, which can be attracted by MSAEA and make it less interference. Consequently, they can be separated by external magnet and eluted using proper solvent and become free state to be detected by UPLC. The result showed that the method had good linearity (r= 0.990–0.997), and the limits of detection (LODs) of four Sudan dyes were from 15 ng/mL. Recoveries obtained by analyzing the five spiked chili oil samples were in the range of 76.4-86.8% and the intra-day and inter-day relative standard deviations (RSDs) were between 3.1-7.6% and 5.2-10.3%, respectively. The results indicated that the novel method could be applied successfully for the determination of Sudan dyes in chili oil samples. MSAEA prepared by this method has high selectivity, easy synthesis, and low solvent consumption, compared to aluminum oxide adsorbent used in national standard method. In addition, our material is consistent with the requirements of green chemistry.