Tamburini Diego, Dyer Joanne, Bonaduce Ilaria
Department of Scientific Research, The British Museum, Great Russell Street, WC1B 3DG, London, United Kingdom.
Department of Chemistry and Industrial Chemistry, University of Pisa, via G. Moruzzi 13, I-56124, Pisa, Italy.
Sci Rep. 2017 Nov 1;7(1):14784. doi: 10.1038/s41598-017-14907-7.
A strategy based on electrospray ionisation (ESI) in negative mode coupled with quadrupole-time of flight (Q-ToF) detection techniques was adopted to characterise some samples of shellac resin. Flow injection analysis (FIA) was used to investigate the distribution of the components of the resin. Eight groups of compounds with increasing masses were detected and assigned to free acids, esters and polyesters with up to eight units. High pressure liquid chromatography (HPLC) enabled the compounds to be chromatographically separated. Accurate molecular masses and tandem mass (MS/MS) spectra interpretation were used to characterise the different compounds, assigning and/or suggesting molecular structures. In some cases, highly detailed information about the ester linkages was provided by the MS/MS spectra, enabling the different isomers to be distinguished. Oxidation products were also identified in the samples and differences were observed in terms of hydrolysis and oxidation. In addition to providing the first characterisation of shellac by HPLC-ESI-Q-ToF and an atlas of MS/MS spectra of shellac components, this work demonstrates the suitability of the proposed strategy for characterising the resin, and provides the identification of previously unknown degradation products and minor components. This represents a significant step forward in the chemical knowledge of this material.
采用一种基于负模式电喷雾电离（ESI）与四极杆飞行时间（Q-ToF）检测技术相结合的策略来表征紫胶树脂的一些样品。采用流动注射分析（FIA）来研究树脂成分的分布。检测到八组质量递增的化合物，并将其归类为游离酸、酯和最多含八个单元的聚酯。高压液相色谱（HPLC）能够对这些化合物进行色谱分离。利用精确的分子量和串联质谱（MS/MS）谱图解析来表征不同的化合物，确定和/或推测分子结构。在某些情况下，MS/MS谱图提供了有关酯键的高度详细信息，从而能够区分不同的异构体。还在样品中鉴定出了氧化产物，并观察到了水解和氧化方面的差异。除了首次通过HPLC-ESI-Q-ToF对紫胶进行表征并给出紫胶成分的MS/MS谱图集外，这项工作还证明了所提出的策略适用于表征该树脂，并鉴定出了先前未知的降解产物和次要成分。这代表了在该材料化学知识方面向前迈出的重要一步。
