Patent ID: 7973926

Claim:
A method for determining an olefin concentration of an olefin-containing fuel, the method comprising: obtaining a linear calibration curve described by an equation: Olefin vol %= M ·(area ratio)+ B wherein: Olefin vol % comprises an actual olefin concentration, by volume percent; M comprises a slope of the linear calibration curve; “area ratio” comprises a ratio of a first area in an olefin spectral region compared to a second area in a first chemical spectral region of a Raman spectrum of a first chemical in a linear-calibration reference sample; and B comprises a Y-intercept of the linear calibration curve; obtaining a first Raman spectrum from a concentration-calculation reference sample; obtaining a second Raman spectrum from an olefin-containing fuel sample having an unknown olefin concentration; calculating a test area ratio by dividing the first area in the olefin spectral region of the second Raman spectrum by the second area in a second chemical spectral region of a second chemical in the first Raman spectrum obtained from the concentration-calculation reference sample; and calculating the unknown olefin concentration according to the linear calibration curve.