Llana-Ruíz-Cabello M, Pichardo S, Jiménez-Morillo N T, González-Vila F J, Guillamón E, Bermúdez J M, Aucejo S, Camean A M, González-Pérez J A
Universidad de Sevilla, Profesor García González n°2, 41012 Seville, Spain.
IRNAS-CSIC, Av. Reina Mercedes, 10, 41012 Seville, Spain.
J Chromatogr A. 2017 Nov 24;1525:145-151. doi: 10.1016/j.chroma.2017.10.023. Epub 2017 Oct 8.
Compound-specific isotope analysis (CSIA) usually requires preparative steps (pretreatments, extraction, derivatization) to get amenable chromatographic analytes from bulk geological, biological or synthetic materials. Analytical pyrolysis (Py-GC/MS) can help to overcome such sample manipulation. This communication describe the results obtained by hyphenating analytical pyrolysis (Py-GC) with carbon isotope-ratio mass spectrometry (IRMS) for the analysis of a polylactic acid (PLA) a based bio-plastic extruded with variable quantities of a natural plant extract or oregano essential oil. The chemical structural information of pyrolysates was first determined by conventional analytical pyrolysis and the measure of δC in specific compounds was done by coupling a pyrolysis unit to a gas chromatograph connected to a continuous flow IRMS unit (Py-GC-C-IRMS). Using this Py-CSIA device it was possible to trace natural additives with depleted δC values produced by C3 photosystem vegetation (cymene: -26.7‰±2.52; terpinene: -27.1‰±0.13 and carvacrol: -27.5‰±1.80 from oregano and two unknown structures: -23.3‰±3.32 and -24.4‰±1.70 and butyl valerate: -24.1‰±3.55 from Allium spp.), within the naturally isotopically enriched bio-plastic backbone derived from corn (C4 vegetation) starch (cyclopentanones: -14.2‰±2.11; lactide enantiomers: -9.2‰±1.56 and larger polymeric units: -17.2‰±1.71). This is the first application of Py-CSIA to characterize a bio-plastic and is shown as a promising tool to study such materials, providing not only a fingerprinting, but also valuable information about the origin of the materials, allowing the traceability of additives and minimizing sample preparation.
化合物特异性同位素分析（CSIA）通常需要进行制备步骤（预处理、萃取、衍生化），以便从大量地质、生物或合成材料中获得适合色谱分析的分析物。分析热解（Py-GC/MS）有助于克服此类样品处理问题。本通讯描述了将分析热解（Py-GC）与碳同位素比率质谱（IRMS）联用，用于分析一种聚乳酸（PLA）基生物塑料的结果，该生物塑料中挤出了不同量的天然植物提取物或牛至精油。热解产物的化学结构信息首先通过常规分析热解确定，特定化合物中δC的测量是通过将热解单元与连接到连续流IRMS单元的气相色谱仪联用（Py-GC-C-IRMS）来完成的。使用这种Py-CSIA装置，可以追踪由C3光系统植被产生的具有贫化δC值的天然添加剂（伞花烃：-26.7‰±2.52；萜品烯：-27.1‰±0.13；香芹酚：-27.5‰±1.80，来自牛至，还有两个未知结构：-23.3‰±3.32和-24.4‰±1.70；以及戊酸丁酯：-24.1‰±3.55，来自葱属植物），这些添加剂存在于源自玉米（C4植被）淀粉的天然同位素富集的生物塑料主链中（环戊酮：-14.2‰±2.11；丙交酯对映体：-9.2‰±1.56和更大的聚合物单元：-17.2‰±1.71）。这是Py-CSIA首次应用于表征生物塑料，显示出它是研究此类材料的一种有前景的工具，不仅提供了指纹图谱，还提供了有关材料来源的有价值信息，允许追踪添加剂并最大限度地减少样品制备。
