Proceedings e report - Firenze University Press

CHARACTERIZATION OF WATERLOGGED WOOD BY INFRARED SPECTROSCOPY
Fig. 4. Linear regression plot of estimated vs. laboratory-evaluated holocellulose content for the analysed
samples. The regression model refers only to the model obtained with open black circles, corresponding only to
elm samples from Pisa and Comacchio with low ash content (below 6.9% for all of them). The other circles are
samples with ash content above 10%, including elm, cypress and oak.
3.3. Influence of sample inhomogeneity
Fig. 5 shows two normalized spectra obtained in two different portions of the same fine powder and
apparently homogenised meal of the sample np_A07 (Naples, ship A). As can be observed the two
spectra show differences most noticeable at 1454, 1420, and 1024 cm -1 .
Fig. 5. Min-Max normalized (1800-1480 cm -1 ) ATR-FTIR spectra obtained in two different portions of the
extracted meal of the same sample, np_A07, from ship A of Naples. Main differences can be seen at 1454, 1420
and 1024 cm -1 .
If the two spectra are included in the regression line (Fig. 4), two different values of holocellulose
(41% and 55%) are obtained. This addresses the question of the representativeness of the aliquot used
to obtain the spectra that could be handled with a careful homogenisation of the samples
complemented with an increased number of spectra per sample.
4. Conclusions
The results obtained suggest that it would be possible to build models to assess the holocellulose
content of waterlogged archaeological wood by means of ATR-FTIR analysis using simple linear
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