The purpose of this paper is to demonstrate the accuracy of physicochemical
determinations based on equations calculated by multivariate analysis of n
ear infrared spectra which gives access to simultaneous analyses both on-li
ne and off-line. Detailed results concerning the determination of the refra
ctive index at 20 degrees C, the density, the weight% of hydrogen, the % of
aromatic cal;bott, the weight% of mono-, di- and total aromatics and the c
etane number on mid-distillates are given in a shorter time than using the
conventional approach by standardized methods. It is shown that near infrar
ed spectroscopy combined with chemometrics should allow detailed and precis
e comparisons of the hydrotreatment process efficiencies.