A new method for the quantification of 2-EHN (2-ethylhexyl nitrate) was developed and validated. In order to speed up and simplify the chemical analysis of diesel samples throughout inspection procedures, we propose a single analytical method to determine 2-ethylhexyl nitrate by using the distillation curves routine assay used to evaluate the quality of diesel (ASTM D86). This test was allied with multivariate calibration based on PLS (partial least squares) regression. The results were comparable with reference methodology. Using distillation curves of commercial diesel samples results in a prediction of the cetane improver content with relative standard deviations lower than 12% for all fuel samples. Since this correlation was established using commercial samples, the new approach is immediately applicable in the petrochemical industry, which needs an adaptation to biodiesel/diesel blends.