In this paper the application of near infrared (NIR) spectroscopy for the determination of petroleum macromolecules content in model systems is reported. Eighty (80) solutions of three main types of oil macromolecules (asphaltenes, resins, and paraffins) in toluene were studied. NIR spectra within the range 8000–14,000 cm^–1 were used to construct calibration models using the partial least squares method. The low prediction error of the models (0.43, 0.79 and 0.39% w/w for asphaltenes, resins and paraffins, respectively) indicate that NIR spectroscopy can be applied to analyse the petroleum macromolecule content in natural systems (crude oil and its refined products).

Keywords: petroleum (crude oil), macromolecules, NIR, polymers, partial least squares (PLS) regression