Evaluation of the infrared spectroscopy method for the quantification of NANOLIPE marker in feces of dairy cattle

LIPE® is an external marker obtained from lignin isolated from Eucaliptus grandis and enriched with phenolic groups that is used to estimate dry matter intake and digestibility (Saliba et al., 2003). Recently, methodological improvements in obtaining LIPE® led to the production of a newer and better version of this marker. Its particles have now reached the nano scale and for this reason it was called NANOLIPE (Saliba et al., 2012). The Fourier Transform Infrared Spectroscopy (FT-IR) is used for the quantification of NANOLIPE in feces. However, one of the key points to ensure the quality of the results is to assess the linearity of the calibration curves used in the determinations (Thompson, 2005). Therefore, the aim of this study was to statistically evaluate the linearity of the FT-IR method in quantifying NANOLIPE in feces of dairy cattle.