Method for predicting crude oil nitrogen content by infrared spectroscopy

A method for predicting crude oil nitrogen content by infrared spectroscopy comprises the following steps: (1) collecting various crude oil samples, determining the nitrogen contents of the crude oil samples by a standard method, establishing a crude oil nitrogen content matrix Y; (2) determining infrared spectra of the collected various crude oil samples at different temperatures, performing first-order or second order differential processing, establishing a three dimensional spectrum matrix X (I*J*K) based on absorbances at characteristic spectrum zones of 730-851 cm-1 and 1029-1360 cm-1, wherein I is the number of the crude oil samples, J is the wavelength point number of the characteristic spectrum zones, and K is the temperature change value, establishing a correction model with the crude oil nitrogen content matrix established by the standard method by using a multidimensional partial least squares method; (3) determining the infrared spectra of a crude oil sample to be determined at different temperatures under a same condition as the collected crude oil samples, performing first-order or second order differential processing, establishing a three dimensional spectrum matrix Xun based on absorbances at characteristic spectrum zones of 730-851 cm-1 and 1029-1360 cm-1, substituting Xun into the correction model established in step (2) to obtain the nitrogen content of the crude oil sample to be determined. The method is rapid in analysis speed, high in testing accuracy, and good in repeatability.