In situ Raman mapping of art objects.

Raman spectroscopy has grown to be one of the techniques of interest for the investigation of art objects. The approach has several advantageous properties, and the non-destructive character of the technique allowed it to be used for in situ investigations. However, compared with laboratory approaches, it would be useful to take advantage of the small spectral footprint of the technique, and use Raman spectroscopy to study the spatial distribution of different compounds. In this work, an in situ Raman mapping system is developed to be able to relate chemical information with its spatial distribution. Challenges for the development are discussed, including the need for stable positioning and proper data treatment. To avoid focusing problems, nineteenth century porcelain cards are used to test the system. This work focuses mainly on the post-processing of the large dataset which consists of four steps: (i) importing the data into the software; (ii) visualization of the dataset; (iii) extraction of the variables; and (iv) creation of a Raman image. It is shown that despite the challenging task of the development of the full in situ Raman mapping system, the first steps are very promising.This article is part of the themed issue 'Raman spectroscopy in art and archaeology'.

Evaluation of portable Raman spectroscopy and handheld X-ray fluorescence analysis (hXRF) for the direct analysis of glyptics.

In archaeometry, the advantages of a combined use of Raman spectroscopy and X-ray fluorescence spectroscopy are extensively discussed for applications such as the analysis of paintings, manuscripts, pottery, etc. Here, we demonstrate for the first time the advantage of using both techniques for analysing glyptics. These engraved gemstones or glass materials were originally used as stamps, to identify the owner, for instance on letters, but also on wine vessels. For this research, a set of 64 glyptics (42 Roman glass specimens and 22 modern ones), belonging to the collection of the museum 'Quinta das Cruzes' in Funchal (Madeira, Portugal), was analysed with portable Raman spectroscopy and handheld X-ray fluorescence (hXRF). These techniques were also used to confirm the gemological identification of these precious objects and can give extra information about the glass composition. Raman spectroscopy identifies the molecular composition as well as on the crystalline phases present. On the other hand, hXRF results show that the antique Roman glass samples are characterised with low Pb and Sn levels and that the modern specimens can be discriminated in two groups: lead-based and non-lead-based ones.

[Occupational asthma caused by isocyanates]. / Asthme professionnel aux isocyanates.

The aim of our study is to find whether the percentage of RAST positives to isocyanates within a company is a reflection of the exposure of the workers. Specific IgE was sought in 199 workers from ten companies where isocyanates were used. Twenty of them were followed for some time (june 87 to september 90). A non-exposed reference group was used for comparison. Measurements were made by the Pharmacia RAST-ELISA Method. In some cases, controls were made by RAST-RIA and CAPS ELISA/RIA. Results show that the proportion of positive RAST varies from one organisation to another and is probably a measure of the type and intensity of the exposure; the improvement of the working conditions to reduce the ambient concentration reduces, in time, the proportion of positive RAST; there were no positive RAST in the reference group; the conditions of taking and storage of blood samples before analysis influences the result. In conclusion, measurement of specific IgE may be an useful alternative to measurement of ambient concentration for following workers exposed to isocyanates.

[Asthma and isocyanates]. / Asthme et isocyanates.

1. After having reviewed all the 22 patients in Belgium who are indemnified for isocyanate occupational asthma, the authors cannot find any significant factor that would permit screening and previous eviction (atopy, smoking habits). Every patient suffers from a non-specific bronchial responsiveness even after the end of exposure. 2. The specific RAST HDI, MDI, TDI, performed on 26 exposed workers suggests an IgE-mediated sensitization, that does not appear to be a reliable diagnostic or prognostic factor of the disease.