Szterk et al. (Food Chemistry 243 (2018) 403–409) have recently analyzed the content of menaquinone-7 (MK-7) in eight dietary supplements. The authors concluded that five out of eight were below the declared content. For all samples, the authors used tetrahydrofuran (THF) to extract MK-7 prior to analysis. Two of the tested products that were below the declared content were microencapsulated MK-7 which had a coating with limited solubility in THF. By dissolving the coating with water and ethanol prior to extraction with ethyl acetate, all MK-7 will be made accessible prior to analysis by HPLC. We have repeated the analysis of the two microencapsulated products that Szterk et al. claimed were below the declared content, and have shown they contain 102% and 105% of the label claim. Since Szterk et al. have used a solvent that does not dissolve the coating on microencapsulated MK-7, their conclusion is not justified and is thus misleading.

Szterk 等人。(Food Chemistry 243 (2018) 403–409) 最近分析了八种膳食补充剂中甲萘醌 7 (MK-7) 的含量。作者得出的结论是，八分之五的含量低于声明的含量。对于所有样品，作者在分析前使用四氢呋喃 (THF) 提取 MK-7。两种低于声明含量的测试产品是微胶囊化的 MK-7，其涂层在 THF 中的溶解度有限。通过在用乙酸乙酯萃取之前用水和乙醇溶解涂层，所有 MK-7 将在 HPLC 分析之前变得可及。我们重复了 Szterk 等人的两种微胶囊化产品的分析。声称低于声明的含量，并显示它们包含标签声称的 102% 和 105%。由于 Szterk 等人。