Department of Analytical Chemistry, Institute of Fine Chemistry and Nanotechnology, Edificio Anexo Marie Curie, Campus de Rabanales, Córdoba, Spain.
J Chromatogr A. 2011 Dec 16;1218(50):8996-9002. doi: 10.1016/j.chroma.2011.10.041. Epub 2011 Oct 21.
A supramolecular solvent (SUPRA) made up of octanoic acid aggregates is proposed for the microextraction of bixin and norbixin, the two major components of the natural food colouring annatto, in food. The procedure involved the extraction of sub-gram quantities (200mg) of homogenized food with 0.8mL of the supramolecular solvent. The overall sample treatment took about 20 min, and several samples could be simultaneously treated using conventional lab equipment. No clean-up or solvent evaporation were required. Extraction efficiencies mainly depended on the major components making up the SUPRAS (i.e. octanoic acid and tetrahydrofuran) and were not affected by the pH or the temperature in the ranges studied (1-4 and 10-80°C, respectively). Bixin and norbixin in the extracts were quantified by liquid chromatography (LC) and diode array detection (DAD). They were separated in a Hypersil C18 column using a mobile phase consisting of 5% acetic acid and methanol (15:85, v/v). The retention times for norbixin and bixin standards were 5.1 and 8.6 min, respectively. Recoveries in samples ranged between about 78% and 113%. The precision of the method, expressed as relative standard deviation, was about 1.5% and the quantitation limits for bixin and norbixin were 0.19 and 0.23 mg kg(-1), respectively, which were far below the maximum limits permitted by the European Union for the level of addition to food. Concentration of norbixin in samples belonging to the five major groups of food commodities defined in the literature, ranged between 3.75 and 43.8 mg kg(-1) whereas bixin was only found in one snack sample (6.6 mg kg(-1)). The method is simple and rapid, while delivering accurate and precise results, and can be used for the routine determination of annatto in food for the control of the compliance of current legislation.
一种由辛酸聚集物组成的超分子溶剂（SUPRA）被提议用于从食品中微萃取胭脂树红和降胭脂树红，这是天然食用色素胭脂树的两种主要成分。该方法涉及用 0.8mL 的超分子溶剂提取 200mg 均质食品。整个样品处理过程耗时约 20 分钟，并且可以使用常规实验室设备同时处理多个样品。不需要净化或溶剂蒸发。萃取效率主要取决于构成 SUPRAS 的主要成分（即辛酸和四氢呋喃），并且不受研究范围内的 pH 值或温度的影响（分别为 1-4 和 10-80°C）。提取液中的胭脂树红和降胭脂树红通过液相色谱（LC）和二极管阵列检测（DAD）定量。它们在 Hypersil C18 柱上用由 5%乙酸和甲醇（15:85，v/v）组成的流动相分离。降胭脂树红和胭脂树红标准品的保留时间分别为 5.1 和 8.6min。样品中的回收率在约 78%和 113%之间。该方法的精密度，以相对标准偏差表示，约为 1.5%，胭脂树红和降胭脂树红的定量限分别为 0.19 和 0.23mgkg(-1)，远低于欧盟对食品添加剂水平的最大允许限量。文献中定义的五类主要食品中降胭脂树红的浓度在 3.75 和 43.8mgkg(-1)之间，而胭脂树红仅在一种零食样品中发现（6.6mgkg(-1)）。该方法简单快速，可提供准确和精确的结果，可用于常规检测食品中的胭脂树红，以控制现行法规的合规性。
