Abstract: Nitrogen element exerts strong interference in the ultraviolet fluorescence method for determination of total sulfur content in detergent additives for diesel fuel and results in great inaccuracy. This problem was investigated and solved by using high nitrogen suppressor. The effects of the installation of high nitrogen suppressor on elimination of the interference were studied. The working curve was established and the linearity of the working curve was investigated after the test condition was set up. The accuracy and the lower limit of detection of sulfur content were also investigated. The results showed that the strong interference problem is solved and the accuracy of the method is improved in determination of total sulfur content in diesel detergent additives. The working curve is linear up to 0.9998; the practical detection the lower limit is 0.2 mg?L-1. The relative standard deviation is less than 5% in the determination of practical samples.

Key words: sulfur, nitrogen, ultraviolet fluorescence, diesel fuel detergent, elimination