METHOD FOR DETECTING DRAG REDUCER ADDITIVES IN GASOLINE

A method for detecting polymer-based drag reducer additives in gasoline. One embodiment of the invention is a method for detecting the concentration of polymer-based drag reducer additives in gasoline, the method including the following: (a) placing a gasoline sample in a receptacle having at least two adjacent clear sides and irradiating one of the two clear sides of the receptacle with a pulsed laser beam, the pulsed laser beam having a wavelength in the ultra violet region shorter than 300 nm; (b) detecting laser-induced fluorescence wavelength resolved spectrum at 90° angle relative to the incident laser beam and through a slit defined in a diffraction screen, the diffraction screen being placed at a pre-defined first distance from the receptacle; (c) adjusting the position of the receptacle and slightly de-focusing the collimating lenses so that the low resolution fluorescence wavelength-resolved spectrum of the gasoline sample appears with a first peak at about 380 nm and a second peak at about 430 nm; (d) recording the laser-induced fluorescence wavelength-resolved spectra of the gasoline sample within a defined time-gate starting at the end of the temporal span of the laser pulse; and (e) comparing the percentage intensity of the first peak relative to the second peak for the laser-induced fluorescence spectrum near 380 nm of the gasoline sample to that of a gasoline sample free of any polymer-based drag reducer additives. In another embodiment of the method, the location of the diffraction-screen is at the pre-defined distance of between 0.5 mm to 2 mm from the side of the receptacle. In another embodiment of the method, the time- gate in step (d) is of 3 ns width and starting immediately after the end of the laser pulse. L'invention porte sur un procédé pour détecter des additifs réducteurs de traînée à base de polymères dans de l'essence. Un mode de réalisation de l'invention porte sur un procédé pour détecter la concentration d'additifs réducteurs de traînée à base de polymères dans de l'essence, lequel procédé comprend les étapes suivantes, consistant à : (a) disposer un échantillon d'essence dans un récipient ayant au moins deux côtés transparents adjacents et irradier l'un des deux côtés transparents du récipient avec un faisceau laser pulsé, le faisceau laser pulsé ayant une longueur d'onde dans la région des ultraviolets plus courte que 300 nm ; (b) détecter un spectre à longueur d'onde de fluorescence résolue induit par laser à un angle d