Determining the lowest sulfur detection limit in diesel fuel by ultraviolet fluorescence

Abstract

This technical review article focuses on determining a robust and precise lower-level sulfur detection procedure. When measuring under 0.1 ppm and approaching zero values, the limits of the instrument are pushed to separate real signal response from noise. One of the performance parameters in method validation studies is to determine these near-zero value samples reliably when the instrument works near the noise signal level. The study examined the early stages of the method development process, regarding the determination of the validation parameters limit of blank, limit of detection (LOD), and limit of quantification (LOQ). The sulfur content in diesel fuel was determined with guidance from the standard ISO 20846:2011. The average sulfur readings of a diesel test sample and blank (99% iso-octane) were measured as 3.9 and 0.0196 ppm, respectively. For a 1.5% diluted diesel test sample the mean sulfur value was measured as 0.0613 ppm and this value was verified as the LOD. For a 3% diluted diesel test sample the mean sulfur value was measured as 0.1158 ppm and this result was verified as the LOQ. The LOD and LOQ were tested for conformity. The accuracy of these tested values was checked according to EUROCHEM guidelines.