Nutrition and Food Security Research Center, Department of Food Science and Technology, School of Nutrition and Food Science, Isfahan University of Medical Sciences, Isfahan, Iran.
Nutrition and Food Security Research Center, Department of Food Science and Technology, School of Nutrition and Food Science, Isfahan University of Medical Sciences, Isfahan, Iran.
J Chromatogr B Analyt Technol Biomed Life Sci. 2023 Sep 1;1229:123902. doi: 10.1016/j.jchromb.2023.123902. Epub 2023 Oct 4.
Melamine is added illegally to milk and dairy products to increase the amount of apparent protein. This organic nitrogen rich chemical compound has been of great challenge in food safety based on its adverse effect on health. Therefore, the extraction and determination of melamine from milk is necessary. Recently, ionic liquid (ILs) as solvent usage has been noticeable for low melting point, low toxicity, high thermal stability, and high extraction capabilities in a wide range of separation processes. ILs are introduced as organic-inorganic salts and green solvents in microextraction preparation. Therefore, in this study, three ionic liquids ([C6mim][NTF2], [C4mim][NTF2] and [C2mim][NTF2] ILs) were prepared and employed as an extraction solvent in dispersive liquid-liquid microextraction (DLLME) of melamine from milk samples followed by HPLC-UV. The selected ILs were designed using three types of alkyl-imidazolium (as the short organic cations) and bis (tri fluoro methyl sulfonyl) imide as anion and characterized by ATR-FTIR spectra, carbon, and hydrogen Nuclear Magnetic Resonance spectroscopy (H&C-NMR) and energy-dispersive X-ray spectroscopy (EDX). These techniques confirmed the formation of functional groups, the structure of hydrogen and carbon atoms, and various elements of ionic bond between imidazolium and bis (tri fluoro methyl sulfonyl) imide. In the next step, the effect of significant parameters, including type and volume of ILs, adsorption time, pH of the sample solution, and sample volume, were optimized. Under the optimal conditions, the limits of detection (LOD), limits of quantification (LOQ), and linearity range were obtained 63.64 µg kg, 210.03 µg kg and 210.03-1000 µg kg, respectively, for as prepared [C6mim][NTF2] as the best ILs. Notably, the achieved LOQ was lower than the maximum residue level (MRL) for the melamine residue in dairy products. Eventually, the proposed method was applied to detect melamine in milk samples, and the relative recoveries were examined as 79.6-105.0 %.
三聚氰胺被非法添加到牛奶和乳制品中以增加表观蛋白质的含量。这种富含有机氮的化合物因其对健康的不良影响，对食品安全构成了极大的挑战。因此，从牛奶中提取和测定三聚氰胺是必要的。最近，离子液体（ILs）作为溶剂的使用因其低熔点、低毒性、高热稳定性和在广泛的分离过程中具有高萃取能力而引人注目。ILs 被引入到微萃取制备中作为有机-无机盐和绿色溶剂。因此，在本研究中，制备了三种离子液体（[C6mim][NTF2]、[C4mim][NTF2]和[C2mim][NTF2] ILs），并将其作为萃取溶剂用于分散液液微萃取（DLLME）中，从牛奶样品中萃取三聚氰胺，然后用 HPLC-UV 进行分析。所选择的 ILs 采用三种类型的烷基-咪唑（作为短有机阳离子）和双（三氟甲基磺酰基）亚胺作为阴离子进行设计，并通过 ATR-FTIR 光谱、碳和氢核磁共振光谱（H&C-NMR）和能谱（EDX）进行表征。这些技术证实了官能团的形成、氢和碳原子的结构以及咪唑𬭩和双（三氟甲基磺酰基）亚胺之间离子键的各种元素。下一步，优化了重要参数的影响，包括 ILs 的类型和体积、吸附时间、样品溶液的 pH 值和样品体积。在最佳条件下，获得了制备的 [C6mim][NTF2] 的检出限（LOD）、定量限（LOQ）和线性范围分别为 63.64µgkg、210.03µgkg 和 210.03-1000µgkg。值得注意的是，所得到的 LOQ 低于乳制品中三聚氰胺残留的最大残留限量（MRL）。最终，该方法应用于检测牛奶样品中的三聚氰胺，相对回收率为 79.6-105.0%。
