Determination of Chlorine in Crude Oil by High-Resolution Continuum Source Graphite Furnace Molecular Absorption Spectrometry Using AlCl, InCl, and SrCl Molecules

In this work, high-resolution continuum source graphite furnace molecular absorption spectrometry (HR-CS GF MAS) using AlCl, InCl, and SrCl molecules was proposed for direct Cl determination in crude oil. Crude oil analysis was performed by pipetting masses of crude oil directly on the graphite platform. Calibration was performed using aqueous standard solutions containing chlorine. A solution containing Sr2+ ions should be used to increase the sensitivity for AlCl and InCl molecules. For SrCl, only Sr2+ solution was used and the graphite platform should be covered with a Zr permanent modifier. Accuracy was evaluated using certified reference material (NIST 1634c, fuel oil) and also by comparison of results obtained with HR-CS GF MAS to those obtained by microwave-induced combustion (MIC), microwave-assisted extraction (MAE), ASTM D6470-99, and neutron activation analysis (NAA). Significant differences were not observed by comparison of results obtained by HR-CS GF MAS to the certified reference value and the other methods for Cl determination (95% confidence level). The AlCl molecule provided the lowest characteristic mass (0.28 ng). Limits of detection (LODs) of 1.4 and 0.5 mg kg(-1) of Cl were obtained for AlCl and SrCl molecules, respectively. Sample preparation was minimized using direct analysis of crude oil combined with HR-CS GF MAS providing better LOD when compared to conventional methods for Cl determination. HR-CS GF MAS using AlCl and SrCl molecules was suitable for quality control of crude oil for Cl determination in compliance with the requirements of crude oil industries.