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Molecules 2018, 23(5), 1056; https://doi.org/10.3390/molecules23051056

Analysis of Menaquinone-7 Content and Impurities in Oil and Non-Oil Dietary Supplements

Department of Spectrometric Methods, National Medicines Institute, 30/34 Chełmska, 00-725 Warsaw, Poland
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Received: 17 March 2018 / Revised: 24 April 2018 / Accepted: 28 April 2018 / Published: 1 May 2018
(This article belongs to the Section Analytical Chemistry)
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Abstract

Rapid, global technological development has caused the food industry to use concentrated food component sources like dietary supplements ever more commonly as part of the human diet. This study analysed the menaquinone-7 (MK-7) content of dietary supplements in oil capsule and hard tablet forms. A novel method for separating and measuring geometric isomers of MK-7 in dietary supplements was developed and validated. Eleven different isomers of cis/trans- menaquinone-7 were identified. Identification of cis/trans isomers was performed by combination of HPLC, UPLC and HRMS-QTOF detection, whereas their quantities were determined by DAD detection. The content of menaquinone impurities was ascertained, including cis/trans- menaquinone-6 isomers (5.5–16.9 µg per tablet/capsule) and cis/trans-menaquinone-7 isomers (70.9–218.7 µg tablet/capsule), which were most likely formed during the chemical synthesis of the menaquinone-7. The all-trans MK-7 content was lower than the isomeric form and often lower than what the labels declared. A new method of quantification, developed and validated for menaquinones in oil capsules, provided on average 90% recovery and a limit of quantification (LOQ) of approximately 1 µg mL−1. View Full-Text
Keywords: dietary supplements; menaquinone; cis-isomers; trans-isomers; vitamin K2 dietary supplements; menaquinone; cis-isomers; trans-isomers; vitamin K2
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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).

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Szterk, A.; Bus, K.; Zmysłowski, A.; Ofiara, K. Analysis of Menaquinone-7 Content and Impurities in Oil and Non-Oil Dietary Supplements. Molecules 2018, 23, 1056.

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