Characterization Of Leather Finishing By Ir Spectroscopy And Canonical Variate Analysis

摘要

The finishing process is one of the crucial steps in the process by which the tanning industry transforms leather into an end-product. Therefore, ensuring the required quality in the product requires careful control of this step. Traditionally, the leather tanning industry has used polluting processes and slow analytical methods involving time-consuming separations and also, frequently, the use of environmentally unfriendly reagents. In this work, we used a large matrix of spectroscopic data obtained from 63 leather specimens (34 from Pielcolor and 29 from the laboratories of the Leather Technology School of Igualada) to develop a method allowing the finishing method used on a leather (viz. a resin, wax/oil or grain correction treatment) to be expeditiously, non-destructively identified with the need for no sample treatment. To this end, Fourier transform infrared (FTIR) spectra were recorded with the aid of an ATR module and near-infrared (NIR) spectra with a fibre-optic probe. Chemometric processing of the FTIR or NIR spectral information thus obtained by Principal Component Analysis (PCA) and Canonical Variate Analysis (CVA) allowed the identification of the finishing treatment used on the studied leather samples. The results for the external prediction set (80% of hits with the FTIR model and 60% with the NIR model) were of the same order of magnitude than those obtained by leave-one-out cross-validation of the calibration set (85% with FTIR and 72% with NIR).