Chair of Analytical Food Chemistry, ZIEL Research Center for Nutrition and Food Sciences, Technische Universität München, Alte Akademie 10, D-85354 Freising, Germany.
J Agric Food Chem. 2012 Jul 25;60(29):7129-36. doi: 10.1021/jf3015602. Epub 2012 Jul 13.
The first stable isotope dilution assay for the determination of enniatins A, A1, B, and B1 and beauvericin was developed. The (15)N(3)-labeled enniatins and beauvericin were biosynthesized by feeding two Fusarium strains Na(15)NO(3) and subsequently isolated from the fungal culture. The chemical structures of the biosynthesized products were characterized by LC-MS/MS and (1)H NMR. Standard solutions of (15)N(3)-labeled beauvericin, enniatin A, and enniatin A1 were accurately quantitated by quantitative NMR. On the basis of the use of the labeled products as internal standards, stable isotope dilution assays were developed and applied to various food samples using LC-MS/MS. The sample extracts were directly injected without any tedious cleanup procedures. The limits of detection were 3.9, 2.6, 3.7, 1.9, and 4.4 μg/kg for enniatins A, A1, B, and B1 and beauvericin, respectively. Limits of quantitation were 11.5 (enniatin A), 7.6 (enniatin A1), 10.9 (enniatin B), 5.8 (enniatin B1), and 13.1 μg/kg (beauvericin). Recoveries were within the range between 90 and 120%, and good intraday and interday precisions with coefficients of variation between 1.35 and 8.61% were obtained. Thus, the stable isotope dilution assay presented here is similarly sensitive and precise but more accurate than assays reported before. Analyses of cereals and cereal products revealed frequent contaminations of barley, wheat, rye, and oats with enniatins B and B1, whereas beauvericin was not quantifiable.
建立了用于测定恩镰孢菌素 A、A1、B 和 B1 以及 beauvericin 的首个稳定同位素稀释分析方法。通过喂食两种镰刀菌菌株 Na(15)NO(3)，随后从真菌培养物中分离出来，生物合成了（15）N(3)-标记的恩镰孢菌素和 beauvericin。通过 LC-MS/MS 和（1）H NMR 对生物合成产物的化学结构进行了表征。通过定量 NMR 准确定量了（15）N(3)-标记的 beauvericin、恩镰孢菌素 A 和恩镰孢菌素 A1 的标准溶液。基于使用标记产物作为内标，开发了稳定同位素稀释分析方法，并应用于使用 LC-MS/MS 的各种食品样品。样品提取物无需繁琐的净化程序即可直接进样。恩镰孢菌素 A、A1、B 和 B1 以及 beauvericin 的检测限分别为 3.9、2.6、3.7、1.9 和 4.4 μg/kg。定量限分别为 11.5（恩镰孢菌素 A）、7.6（恩镰孢菌素 A1）、10.9（恩镰孢菌素 B）、5.8（恩镰孢菌素 B1）和 13.1 μg/kg（beauvericin）。回收率在 90%至 120%之间，日内和日间精密度良好，变异系数在 1.35%至 8.61%之间。因此，与以前报道的方法相比，本研究提出的稳定同位素稀释分析方法具有同样的灵敏度和精度，但更准确。对谷物和谷物制品的分析表明，大麦、小麦、黑麦和燕麦经常受到恩镰孢菌素 B 和 B1 的污染，而 beauvericin 则无法定量。
