Infrared (IR) spectroscopic methods may be an effective alternative
to the classical ASTM implementations, since their utilization
allows development of analytical methodologies that are fast and
clean, need only a few amounts of sample and do not require
extensive use of reagents. The main drawback of IR spectroscopic
methods is spectral overlapping of the signals of the analyte(s) of
interest and other contaminations in the sample. Then the usage
of chemometrics methods, such as multivariate calibration or classification,
is required to produce accurate results without needing
any sample treatment [3].