菜籽油（油菜籽）同位素指纹快速一步样品制备方法的评价：考察使用 2,2-二甲氧基丙烷对气相色谱燃烧/热解同位素比质谱法进行化合物特异性稳定碳和氢同位素分析的影响。

Evaluation of a quick one-step sample preparation method for the determination of the isotopic fingerprint of rapeseed (Brassica napus): Investigation of the influence of the use of 2,2-dimethoxypropane on compound-specific stable carbon and hydrogen isotope analyses by gas chromatography combustion/pyrolysis isotope ratio mass spectrometry.

机构信息

Institute IWAR, Technische Universität Darmstadt, Franziska-Braun-Straße 7, Darmstadt, Hessen, DE, 64287, Germany.

Jager Biotech GmbH, An der Ziegelei 57, Groß-Zimmern, DE, 64846, Germany.

出版信息

Rapid Commun Mass Spectrom. 2021 May 15;35(9):e9064. doi: 10.1002/rcm.9064.

DOI:10.1002/rcm.9064

PMID:33554384

Abstract

RATIONALE

Gas chromatographic analyses for vegetable oils require transesterification, which generally involves multiple steps, mainly to generate fatty acid methyl esters (FAMEs). A quick method based on acid-catalyzed transesterification using 2,2-dimethoxypropane (DMP) enables the conversion in one step, in a single reactor. For compound-specific stable carbon and hydrogen isotope analyses (C- and H-CSIA) of individual fatty acids (FAs) in oil, the verification of this one-step method has not yet been reported.

METHODS

In this study, we evaluated the feasibility of the one-step method for C- and H-CSIA of individual FAMEs in rapeseed samples. The focus was on the investigation of the influence of methanol, which was produced from the reactions of DMP with glycerol and water during transesterification, on the accuracy of isotope composition of FAMEs, consequently of the FAs. The reproducibility of the one-step method was assessed by the measurement of the FAMEs from rapeseed and rapeseed oil. For the C- and H-CSIA of individual FAMEs, a gas chromatography combustion/pyrolysis isotope ratio mass spectrometry system was used.

RESULTS

Our results showed that no significant differences arise in the carbon and hydrogen isotope compositions of the selected main FAMEs produced with and without DMP except for the H-CSIA value of C18:3. The reproducibility of the one-step method for rapeseed was in the range of ±0.1 mUr to ± 0.3 mUr for C-CSIA and ±1 mUr to ±3 mUr for H-CSIA of the main FAMEs.

CONCLUSIONS

DMP improves the transesterification efficiency without influencing the accuracy of the C- and H-CSIA of FAMEs. The performance of the one-step method for rapeseed samples for the determination of C- and H-CSIA values of FAMEs is satisfactory. Thus, the applicability of the one-step method for isotopic fingerprint analyses of FAs in oilseeds is reported for the first time.

摘要

原理

气相色谱分析植物油需要进行酯交换反应，通常涉及多个步骤，主要是为了生成脂肪酸甲酯（FAMEs）。一种基于 2,2-二甲氧基丙烷（DMP）酸催化酯交换的快速方法可以在一个反应器中一步完成转化。对于油中单个脂肪酸（FAs）的化合物特异性稳定碳和氢同位素分析（C-和 H-CSIA），尚未报道对此一步法的验证。

方法

在本研究中，我们评估了一步法用于油菜籽样品中单个 FAMEs 的 C-和 H-CSIA 的可行性。重点研究了在酯交换过程中 DMP 与甘油和水反应生成的甲醇对 FAMEs 同位素组成准确性的影响，进而对 FAs 的影响。通过油菜籽和菜籽油中 FAMEs 的测量来评估一步法的重现性。对于单个 FAMEs 的 C-和 H-CSIA，使用气相色谱燃烧/热解同位素质谱系统。