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Annals of Forest Science

, Volume 65, Issue 8, pp 803–803 | Cite as

Correction of moisture effects on near infrared calibration for the analysis of phenol content in eucalyptus wood extracts

  • Thomas Giordanengo
  • Jean-Paul Charpentier
  • Jean-Michel Roger
  • Sylvie Roussel
  • Loïc Brancheriau
  • Gilles ChaixEmail author
  • Henri Baillères
Original Article

Abstract

  • • Methods based on near infrared spectroscopy used to assess wood properties are susceptible to variations in physical parameters (temperature, grain size, etc.). As wood is a hygroscopically sensitive material, we studied the effects of moisture on near infrared absorbance and calibration to accurately determine the application potential of this technique under routine.

  • • A collection of Eucalyptus urophylla × E. grandis hybrid wood pieces were analysed to obtain reference calibration of polyphenol contents in wood extracts via NIR spectra acquired under constant moisture conditions. Other specimens from the same source were assessed to obtain spectra for eight moisture contents spanning a broad variation range. The effects of moisture on absorption and on estimates based on a reference model were analysed.

  • • An increase in moisture content prompted a rise in near infrared absorption over the entire spectrum and for water O-H absorption bands. The polyphenol content estimates obtained by assessing specimens against the reference calibration at variable moisture contents revealed prediction bias. Five correction methods were then tested to enhance the robustness relative to moisture.

  • • In-depth calibration and external parameter orthogonalization (EPO) were found to be the most efficient methods for offsetting this factor.

Keywords

EPO eucalyptus phenols moisture effect correction NIRS 

Correction de l’influence de l’humidité sur l’étalonnage proche infrarouge de la teneur en phénols dans les extraits de bois d’Eucalyptus

Résumé

  • • Les méthodes basées sur la spectroscopie proche infrarouge pour estimer les propriétés du bois sont sensibles aux variations des paramètres physiques (température, granulométrie…). Le bois étant un matériau hygroscopique sensible, l’influence de l’humidité sur l’absorbance et l’étalonnage proche infrarouge a été étudiée afin de mieux considérer les possibilités d’applications dans des conditions réelles.

  • • Un étalonnage de référence de la quantité de polyphénols présents dans les extraits a été établi à partir de spectres d’une collection de bois d’hybrides d’Eucalyptus urophylla × E. grandis à humidité constante fixée. D’autres spectres ont été obtenus sur des échantillons de même provenance mais à 8 teneurs en eau couvrant une large plage de variation. L’influence de l’humidité sur l’absorbance proche infrarouge puis sur l’estimation par le modèle de référence a été analysée.

  • • Une augmentation de l’humidité élève la ligne de base du spectre d’absorbance et également les régions d’absorbance caractéristiques de la liaison O-H de l’eau. Les estimations de la quantité de polyphénols à partir de l’étalonnage de référence sur les échantillons à humidité variable révèlent un biais sur les prédictions.

  • • Parmi les cinq méthodes de correction testées pour rendre l’étalonnage robuste vis-à-vis de l’humidité, l’étalonnage exhaustif et l’EPO (External Parameter Orthogonalisation) s’avèrent être les plus efficaces et permettent de s’affranchir de ce facteur.

Mots-clés

EPO eucalyptus phénols correction effets humidité SPIR 

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Copyright information

© Springer S+B Media B.V. 2008

Authors and Affiliations

  • Thomas Giordanengo
    • 1
  • Jean-Paul Charpentier
    • 2
  • Jean-Michel Roger
    • 3
  • Sylvie Roussel
    • 4
  • Loïc Brancheriau
    • 5
  • Gilles Chaix
    • 6
    Email author
  • Henri Baillères
    • 5
  1. 1.R&D Tonnellerie RadouxJonzacFrance
  2. 2.Unité d’Amélioration, Génétique et Physiologie ForestièresINRA OrléansOrléans Cedex 2France
  3. 3.UMR ITAPCEMAGREFMontpellier Cedex 1France
  4. 4.ONDALYSPrades le LezFrance
  5. 5.PERSYST Department, Production and Processing of Tropical Woods Research UnitCIRADMontpellier Cedex 5France
  6. 6.BIOS Department - TA A-39, Genetic diversity and breeding of forest species unit researchCIRADMontpellier Cedex 5France

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