Liquid chromatography and mass spectrometry for the analysis of acylglycerols in art and archeology

Abstract

Lipid characterization in art and archeology, together with the study of lipid degradation processes, is an important research area in heritage science. Lipid‐based materials have been used as food since ancient times, but also employed as illuminants and as ingredients in cosmetic, ritual, and pharmaceutical preparations. Both animal and plant lipids have also been processed to produce materials used in art and crafts, such as paint binders, varnishes, waterproofing agents, and coatings. Identifying the origin of the lipid materials is challenging when they are found in association with artistic historical objects. This is due to the inherent complex composition of lipids, their widespread occurrence, and the chemical alterations induced by ageing. The most common approach for lipid characterization in heritage objects entails profiling fatty acids by gas chromatography/mass spectrometry after saponification or transesterification. New developments in high‐performance liquid chromatography coupled with mass spectrometry (HPLC‐MS) for the characterization of acylglycerols, together with more efficient sample treatments, have fostered the introduction of liquid chromatography for characterizing the lipid profile in heritage objects. This review reports the latest developments and applications of HPLC‐MS for the characterization of lipid materials in the field of heritage science. We describe the various approaches for sample pretreatment and highlight the advantages and limitations of HPLC‐MS in the analysis of paint and archeological samples. © 2020 John Wiley & Sons Ltd.

The stability of paintings and the molecular structure of the oil paint polymeric network

“…The detailed list of compounds identified is reported in Table S.4. By combining the data interpretation for both the oxidized and non-oxidised species 29 we identified a mixture of linseed oil and traces of safflower oil as the paint binder.…”

“…The detection of a drying oil in a painting is, in general, relatively straightforward, and can be achieved using a variety of analytical approaches, including, most commonly, those based on FTIR 24 – 26 , GC-MS 27 , Py-GC-MS 28 , HPLC-MS 29 .…”

“…Free metal soaps may also be determined by using mass spectrometry 32 , 41 . HPLC-MS based methods are the methods of choice for glyceride profiling in paintings 29 , and flow injection analysis coupled with ESI–MS can help visualise the distribution of glycerides and more abundant oligomers in a paint layer 33 , 42 . While spectroscopic techniques allow the bulk of the sample or its surface to be analysed, based on the instrumental set-up used, GC-MS, HPLC-MS and ESI-MS give only information on the soluble/hydrolysable fraction of the oil matrix.…”

Human metabolite detection by surface-enhanced Raman spectroscopy

“…MS and HPLC can be combined for unknown endogenous or exogenous metabolites characterization in complicated biological samples [ [54] , [55] , [56] ]. However, the combination of these technologies requires expensive equipment, complicated sample preparation and long test time [ 57 ].…”

Soft Ionization mass spectrometry of lipid residues in archaeological findings: ESI vs APCI

“…In both cases, significant characteristic information that are linked to the structural uniqueness of TAGs are lost. Thanks to the relatively recent introduction of soft ionization techniques, handling large molecules with ordinary mass spectrometer analyzers has become possible [2] and thus the study of intact lipid has been introduced also in archaeometry [3]. Specifically, electrospray ionization (ESI) provides ionized analytes by spraying the sample trough a capillary bearing strong electrical field whereas in atmospheric pressure chemical ionization the ionization occurs in gas phase and the energy is provided by the so-called corona discharge needle.…”