Time travelling with microextraction techniques
- Published: Mar 21, 2017
- Author: Rafael Lucena
- Channels: Ion Chromatography / Laboratory Informatics / HPLC / Sample Preparation / Electrophoresis / Gas Chromatography / Detectors / Proteomics & Genomics / Atomic / NMR Knowledge Base / Base Peak / Raman / UV/Vis Spectroscopy / Proteomics / MRI Spectroscopy / X-ray Spectrometry / Infrared Spectroscopy / Chemometrics & Informatics
Just imagine that you could travel back in time to observe the creation of a famous work of art. I am sorry to say that unfortunately this is not possible, at least not yet, in a conventional way. However, we can use analytical techniques to obtain chemical information from ancient objects. In such a case, this chemical info could throw light on the materials used by the artist or the historical context of the object. It is not the same as actual travel in person l, of course, but it's still exciting!
The analysis of ancient objects is not a simple task due to the value and unique nature of the samples. Using invasive and destructive procedures is out of the question so we need to find other alternatives. Spectroscopic techniques are useful but they usually only provide preliminary data. In contrast, mass spectrometry is an excellent technique since it can identify the compounds present in the sample, but the samples are not directly compatible with the technique.
Microextraction techniques can act effectively as bridges between the raw sample and the MS analysis. The low absolute recovery provided by some microextraction techniques is advantageous since it allows the extraction of the target compounds with a negligible effect on the composition of the raw sample. This is the idea behind a recent proposal, a result of a joint collaboration between researchers from Italy and Israel, published in Analytical Chemistry. In this article a ethyl-vinyl acetate (EVA) film is used as support for the immobilization of cation/anion exchange and C8 particles. The resulting film (150-200 µm in thickness) can be placed over the surface of the ancient object to extract different targets which can be analysed by LC-MS. Among the targets, proteins and small molecules which have been used as binding agents and pigments can be highlighted.
The non-invasive nature of the procedure has been carefully considered. On the one hand, the surface of the EVA film was not modified during the extractions and it did not drag residues off the painting. On the other hand, the painting remained unaltered after the extraction. This strategy has been applied to the analysis of real samples where binders (such as casein) and pigments (e.g. carminic acid) have been identified.
- Method for Noninvasive Analysis of Proteins and Small Molecules from Ancient Objects. Anal. Chem.., 2017, 89(6), 3310-3317.
- "San Francesco / santi / Madonna che allatta il Bambino / S. Pietro / S. Paolo / santi / la Trinità / S. Giovanni Battista / Santo vescovo/ S Gerolamo" from Pietro da Alba Gallo. Palazzo Madama Museum, Turin. www.palazzomadamatorino.it/en/node/25230.
Blog post by: Rafael Lucena
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