A novel analytical method for determination of picogram levels of total mercury in gasoline and other petroleum based products

A new and simple sample preparation method has been developed for the determination of mercury in gasoline and other petroleum products. The organo-mercury compounds in the materials are oxidized, while being extracted into the aqueous phase using an oxidant/acid solution, BrCl/HCl. The inorganic mercury is simultaneously extracted into the solution. The mercury extracted into the aqueous phase is then reduced to Hg-0 by SnCl2 and detected by cold vapour atomic fluorescence spectrometer (CVAFS). The detection limit (DL), expressed as 3 S.D. of repeated measurements for the determination of a low concentration sample, was similar to 0.01 ng/g. The method is sensitive enough to determine low levels of mercury in all gasoline samples studied with RSDs < 10%. The recoveries for determination of mercury in a certified reference material, Conoco, Jet Fuel CRM DRM 1080 were close to 100% with an RSD of less than or equal to 5%. Gasoline samples and other petroleum based materials, such as Kerosene, diesel and heating oil from different origins were analyzed and satisfactory results were obtained. The analytical results are independent of the mercury species studied making the use of direct standardization possible, thus ensuring the accuracy and reliability of the method. The concentrations found in most gasoline and other products were at or below 1 ng/g.