Summary

核磁共振作为鱼油补充剂的血脂的快速评价一个强大的工具

Published: May 01, 2017
doi:

Summary

这里,高分辨率1 H和13 C核磁共振(NMR)光谱被用作包封的鱼油补充剂的定量和定性分析的快速和可靠的工具。

Abstract

西方饮食同n-3脂肪酸差,因此建议鱼油补充剂的消费,以增加这些必需营养素的摄入量。这个工作的目的是利用高分辨率1个 H和13利用两个不同的NMR仪器C NMR光谱法证实包封的鱼油补充剂的定性和定量分析;一个500兆赫和850兆赫的仪器。两个质子(1个 H)和碳(13 C)NMR谱可用于定量测定鱼油补充剂的主要成分。在鱼油补充剂脂质的定量是通过适当的NMR信号的积分在相关1D光谱来实现。通过1 H和13 C NMR得到的结果彼此一致,尽管在两个核和两个仪器之间的分辨率和灵敏度的差异。 1 H-NMR报价SA的快速分析相比13 C NMR,作为频谱可被记录在小于1分钟,而相比之下,13点 C NMR分析,它从10分钟持续到一小时。 13 C NMR谱,然而,更加丰富。它可以用于单个脂肪酸更大数量提供定量数据,并可以被用于确定在甘油骨架的脂肪酸的位置分布。两者的核可以提供仅在一个实验中的定量信息,而无需纯化或分离步骤。的磁场的强度主要影响:1个 H NMR谱由于相对于13 C NMR其较低的分辨率,但是,即使是更低的成本NMR仪器可以有效地应用为食品工业和质量控制实验室的标准方法。

Introduction

在饮食Ñ-3脂肪酸的消费已被证明是对几个条件有利如心脏疾病1,2,3,炎性疾病4和糖尿病5。西方饮食被认为是穷人的N-3脂肪酸,因此建议鱼油补充剂的消费,提高n个 -6 / N -3平衡消费者的营养1。尽管鱼油补充剂的消费,最近越来越多,问题仍然是关于安全性,真实性,以及一些产品的质量。鱼油补充剂的快速和准确的成分分析是必不可少的,以正确评估这些商业产品的质量,保证消费者的安全。

鱼油补充评估的最常见方法s为气相色谱法(GC)和红外光谱(IR)。虽然这些都是高度敏感的方法,他们从几个缺点遭受6。 GC分析是因为单独的化合物的分离和衍生化,需要7和分析8,9期间可能发生的脂质氧化耗时(4-8小时)。虽然IR光谱可以是定量,需要一个预测模型,使用偏最小二乘回归(PLSR)构造,但也有例外,其中IR带可以归因于一个单一的化合物10。 PLSR需要大量的样品,从而增加了分析11的时间的分析。出于这个原因,存在的新的分析方法,使大量的鱼油样品的准确,快速分析发展的越来越大的兴趣。组织,如OFFI在健康(NIH)和美国食品和药物管理局(FDA)全国学院膳食补充剂(ODS)的CE与官方分析化学师协会(AOAC)合作开发这些新方法12,13。

一个用于筛选和多组分基质,如膳食补充品的评价最有前途的分析方法,是核磁共振(NMR)光谱14,15。 NMR光谱法有几个优点:它是一种非破坏性的和定量技术,它需要极少的无样品制备,并且其特征在于优良的精确度和再现性。此外,NMR光谱是一种环境友好的方法,因为它仅使用少量的溶剂。 NMR光谱法的主要缺点是其相对低的灵敏度相比其他analytiCAL方法,但是,例如更强的磁场,各种直径的低温探针,先进的数据处理,和通用的脉冲序列和技术在仪表最近的技术进步增加了灵敏度高达nM范围内。虽然核磁共振仪器是成本高,核磁共振波谱仪的长寿命和NMR的许多应用降低了分析的,从长远来看成本。这个详细的视频协议的目的是帮助本领域从业者新避免与1个 H和13个 C NMR光谱分析鱼油补充剂的相关联的缺陷。

Protocol

1. NMR样品制备注意:注意,使用前请咨询所有相关的材料安全数据表(MSDS)。在样品制备中使用的氘代氯仿(CDCL 3)是有毒的。进行样品制备,包括使用通风橱和个人保护设备的时,请使用所有的适当的安全实践(安全眼镜,手套,实验室外套,全长裤,封闭趾鞋)。 1个 H和13个 C样品的制备 用注射器从膳食胶囊提取鱼油?…

Representative Results

1 H和13个 C NMR光谱收集使用两个NMR仪器市售鱼油补充剂; 850 MHz和500 MHz光谱。这些光谱可用于定量测定鱼油的组分,如二十二碳六烯酸(DHA)和二十碳五烯酸(EPA),以及其它化合物,如正 -1酰基链的和营养的重要指标,如正 -6 / N -3比。所述定量可即使不使用内标来进行,然而,定量结果必须表示为相对摩尔百分比。当数据需要以绝对?…

Discussion

修改和策略疑难解答

光谱质量 。 NMR信号,从而NMR谱的分辨率的线宽是高度依赖于匀场,这是用于磁场的均匀性的优化的方法。对于常规分析,1D匀场是足够的,并不需要3D匀场,因为它是通过NMR人员定期进行。 D 2 O中(90:10):如果不是这种情况下,3D匀场必须被分析之前,使用含有0.6毫升氧化氢的样品进行的。为了实现更好更快匀场,样品需要在?…

Divulgations

The authors have nothing to disclose.

Acknowledgements

这项工作是由俄亥俄州立大学食品卫生发现主题和食品科学与技术在美国俄亥俄州立大学的部门支持。作者要感谢俄亥俄州立大学的NMR设施和宾夕法尼亚州立大学的核磁共振设备。

Materials

Avance III 850 NMR instrument Bruker
Avance III 500 NMR instrument Bruker
TCI 5mm probe Bruker Helium cooled inverse (proton deetected) NMR probe featuring three independent channels (1H, 13C, 15N)
BBO prodigy 5mm probe Bruker Nitrogen cooled observe (X-nuclei detected) probe, featuring two channels; one for 1H and 19F detectionand one for X-nuclei (covering from 15N to 31P)
Spinner turbin Bruker NMR spinners are made by polymer materials and they have a rubber o-ring to hold the NMR tube securely in place
Topspin 3.5 Bruker
deuterated chloroform Sigma-Aldrich  865-49-6 99.8 atom % D, contains 0.03 TMS
2,6-Di-tert-butyl-4-methylphenol, Sigma-Aldrich  128-37-0 purity >99%
Fish oil samples
NMR tubes New Era NE-RG5-7 5mm OD Routine “R” Series NMR Sample Tube
BSMS Bruker Bruker Systems Management System; control system device

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Williamson, K., Hatzakis, E. NMR Spectroscopy as a Robust Tool for the Rapid Evaluation of the Lipid Profile of Fish Oil Supplements. J. Vis. Exp. (123), e55547, doi:10.3791/55547 (2017).

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