Evaluation of a FTIR data pretreatment method for Principal Component Analysis applied to archaeological ceramics ☆

Published Date
March 2016, Vol.125:224–229, doi:10.1016/j.microc.2015.11.033

Title 
Evaluation of a FTIR data pretreatment method for Principal Component Analysis applied to archaeological ceramics ☆

• Author 

• Laura Medeghini ^a,1,
• Silvano Mignardi ^a
• Caterina De Vito ^a
• Aida Maria Conte ^b

• aDepartment of Earth Sciences, Sapienza University of Rome, P.le Aldo Moro 5, 00185 Rome, Italy
• bCNR – IGG – UOS Roma, c/o Department of Earth Sciences, Sapienza University of Rome, P.le Aldo Moro 5, 00185 Rome, Italy

Received 14 July 2015. Revised 11 November 2015. Accepted 17 November 2015. Available online 1 December 2015.

Highlights

• •
  A new FTIR data pretreatment method for PCA is proposed.
• •
  Normalization of FTIR data between 0–1 and the second derivative were considered.
• •
  The proposed procedure has been applied to ancient ceramics.
• •
  The manipulation of experimental data and the influence on PCA are minimized.
• •
  The limited number of variables highlights the correspondence between bands and minerals.

Abstract

The aim of this work is to explore the potential of Fourier Transform Infrared (FTIR) spectroscopy and chemometric analysis as a tool to differentiate ceramics having different provenance. We propose a new spectral FTIR data pretreatment method for Principal Component Analysis (PCA) as the selection of a proper algorithm and its application could play an important role in minimizing the manipulation of data. We consider the data in the spectral region between 400 and 1500 cm^{− 1}, since this range takes into account the contribution of the fingerprints of inorganic compounds (below 1000 cm^{− 1}), and the carbonate absorption band at about 1400 cm^{− 1}. Normalization of FTIR data between 0 and 1 has been followed by the calculation of the second derivative, without the smoothing of data; thus resulting in minimizing the manipulation of experimental data and reducing the influence on PCA. The proposed procedure has been applied to ancient potteries from Khirbet al-Batrawy (Jordan), Motya (Trapani, Italy) and the Palatine Hill (Rome, Italy). A series of elaborations with PCA, step by step, is proposed to reduce the number of variables (from more than 1000 to ~ 200). This allowed the identification of the discriminating vibrational bands for each group obtained by PCA to explain the separation of samples on the basis of their mineralogical composition. The application of the statistical data processing proposed here allowed for the discrimination of different ceramic productions.

Keywords

• Archaeological pottery
• FTIR
• PCA
• Pretreatment method
• Provenance

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• ☆
  Selected papers presented at TECHNART 2015 Conference, Catania (Italy), April 27–30, 2015.

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http://www.sciencedirect.com/science/article/pii/S0026265X15003033