Application of FTIR spectroscopy to the characterization of archeological wood.
Two archeological wood samples were studied by attenuated total reflectance Fourier transform infrared (FTIR-ATR) spectroscopy. They originate from a shipwreck in Ribadeo Bay in the northwest of Spain and from a beam wood of an old nave of the Cathedral of Segovia in the central Spain. Principal component analysis was applied to the transposed data matrix (samples as columns and spectral bands as rows) of 43 recorded spectra (18 in the shipwreck and 25 in the beam wood). The results showed differences between the two samples, with a larger proportion of carbohydrates and smaller proportion of lignin in the beam than in the shipwreck wood. Within the beam wood, lignin content was significantly lower in the recent than the old tree rings (P=0.005). These variations can be attributed to species differences between the two woods (oak and pine respectively), with a mixture of guaiacyl and syringyl in hardwood lignin, whereas softwood lignin consists almost exclusively of guaiacyl moieties. The influence of environmental conditions on the FTIR fingerprint was probably reflected by enhanced oxidation of lignin in aerated conditions (beam wood) and hydrolysis of carbohydrates in submerged-anoxic conditions (shipwreck wood). Molecular characterization by analytical pyrolysis of selected samples from each wood type confirmed the interpretation of the mechanisms behind the variability in wood composition obtained by the FTIR-ATR.
Departamento de Edafología y Química Agrícola, Facultad de Biología, Universidade de Santiago de Compostela, Campus Sur s/n, Santiago de Compostela 15782, Spain. Electronic address: traore.mohamed19@gmail.com.
Mohamed
M
Traoré
Instituto de Ciencias del Patrimonio (Incipit), Consejo Superior de Investigaciones Científicas (CSIC), San Roque 2, Santiago de Compostela 15704, Spain. Electronic address: joeri@samage.net.
Joeri
J
Kaal
Departamento de Edafología y Química Agrícola, Facultad de Biología, Universidade de Santiago de Compostela, Campus Sur s/n, Santiago de Compostela 15782, Spain. Electronic address: antonio.martinez.cortizas@usc.es.
Antonio
A
Martínez Cortizas
D001106:Archaeology; D008401:Gas Chromatography-Mass Spectrometry; D005843:Geography; D008031:Lignin / Q000032:analysis; D025341:Principal Component Analysis; D012767:Ships; D013030:Spain; D017550:Spectroscopy, Fourier Transform Infrared; D013696:Temperature; D014934:Wood / Q000737:chemistry*
D008031:Lignin
Beam wood; Carbohydrate; Lignin; Principal component analysis; Shipwreck wood; Transposed matrix