Department of Analytical Chemistry, Facultad de Ciencias, Edificio Anexo Marie Curie, Campus de Rabanales, 14071-Córdoba, Spain.
J Chromatogr A. 2010 Apr 16;1217(16):2376-82. doi: 10.1016/j.chroma.2009.10.085. Epub 2009 Nov 4.
A supramolecular solvent made up of reverse micelles of decanoic acid, dispersed in a continuous phase of THF:water, was proposed for the simple, fast and efficient microextraction of OTA in wheat prior to liquid chromatography-fluorescence determination. The method involved the stirring of 300 mg-wheat subsamples (particle size 50microm) and 350microL of supramolecular solvent for 15min, subsequent centrifugation for 15min and the direct quantitation of OTA in the extract, previous 5.7-fold dilution with ethanol/water/acetic acid (49.5/49.5/1), against solvent-based calibration curves. No clean-up of the extracts or solvent evaporation was needed. Interactions between the supramolecular solvent and major matrix components in the wheat (i.e. carbohydrates, lipids and proteins) were investigated. The reverse micelles in the extractant induced gluten flocculation but only in the coacervation region of lower analytical interest (i.e. at percentages of THF above 11%). The quantitation of OTA was interference-free. Representativity of the 300 mg-wheat subsamples was proved by analysing a reference material. OTA recoveries in wheat ranged between 84% and 95% and the precision of the method, expressed as relative standard deviation, was 2%. The quantitation limit of the method was 1.5microgkg(-1) and was below the threshold limit established for OTA in raw cereals by EU directives (5.0microgkg(-1)). The method developed was validated by using a certified reference material and it was successfully applied to the determination of OTA in different wheat varieties from crops harvested in the South of Spain. OTA was not detected in any of the analysed samples. This method allows quick and simple microextraction of OTA with minimal solvent consumption, while delivering accurate and precise data.
一种由癸酸反胶束组成的超分子溶剂,分散在 THF:水的连续相中,被提议用于在高效液相色谱-荧光检测之前,对小麦中的OTA 进行简单、快速和有效的微提取。该方法涉及搅拌 300mg 小麦样品(粒径 50μm)和 350μL 超分子溶剂 15min,随后离心 15min,直接对提取物中的 OTA 进行定量,之前用乙醇/水/乙酸(49.5/49.5/1)进行 5.7 倍稀释,与基于溶剂的校准曲线相对。无需对提取物进行净化或溶剂蒸发。研究了超分子溶剂与小麦中主要基质成分(即碳水化合物、脂质和蛋白质)之间的相互作用。萃取剂中的反胶束诱导面筋絮凝,但仅在分析上不感兴趣的凝聚区(即在 THF 百分比高于 11%的情况下)。OTA 的定量不受干扰。通过分析参考物质证明了 300mg 小麦样品的代表性。OTA 在小麦中的回收率在 84%至 95%之间,方法的精密度(表示为相对标准偏差)为 2%。该方法的定量限为 1.5μgkg(-1),低于欧盟指令中规定的原谷物中 OTA 的限量(5.0μgkg(-1))。使用认证参考物质对所开发的方法进行了验证,并成功应用于西班牙南部收获的不同小麦品种中 OTA 的测定。在所分析的样品中均未检测到 OTA。该方法允许快速简单地进行 OTA 微提取,溶剂消耗最小,同时提供准确和精确的数据。