Rapid determination of diesel fuel properties by near-infrared spectroscopy

Abstract The properties of middle distillates, which form diesel fuels, must be monitored during production according to the specific requirements established by standard analytical test methods. Although these test methods are accurate and well accepted, they are time-consuming and expensive. Hence, the best solution is to apply a method that reduces investment, maintenance costs, and time. The aim of this study was to determine seven properties of middle distillates (kinematic viscosity, cold filter plugging point, pour point, contents of sulfur, mono-, di-, and poly-aromatics) using rapid and inexpensive method, near-infrared (NIR) spectroscopy combined with chemometrics multivariate calibrations and the partial least squares (PLS) algorithm. The root mean square error of calibration (RMSEC) and root mean square error of cross-validation (RMSECV) were applied as basic chemometric diagnostic tools to optimize the NIR model predictions. We confidently predicted satisfactory results: the calibration samples were equally distributed along the line of the NIR models and observed a significant correlation between the reference values obtained by the standard methods and the calculated values by the NIR model. Therefore, NIR spectroscopy is an efficient tool for simultaneously determining several diesel fuel properties, which makes it an excellent option for online monitoring during fuel production.