Total Sulfur (TS) stands for the sum parameter of all organic and inorganic sulfur compounds. Trace levels (0.02 – 10.000 mg/kg or ppm by weight) of Total Sulfur are measured with an elemental combustion analyzer according to UV-Fluorescence detection technique or Microcoulometric detection technique. These measurements are carried out mainly in the Oil & Gas Industry.
Petroleum products like gasoline, diesel and fuel oil, may include many organic sulfur compounds. These can be classified as acidic and non-acidic. Acidic sulfur compounds are the thiols (mercaptans). Thiophene, sulfides, and disulfides are examples of non-acidic sulfur. These organic sulfur compounds are products of the degradation of sulfur containing biological components, present during the natural formation of the crude oil. Hydrogen sulfide is the main inorganic compound found in crude oil. Most sulfur compounds can be removed from petroleum streams through hydrotreatment processes, where hydrogen sulfide is produced and the corresponding hydrocarbon released. Hydrogen sulfide is then absorbed in a suitable absorbent and recovered as sulfur.
The sulfur is being removed from petroleum distillates to reduce sulfur dioxide (SO2) emissions when fossil fuels are combusted and in order to protect catalysts in the refining process against poisoning. Elemental combustion analyzers are being used to monitor the amount of sulfur present in crude, intermediates and final products.
Environmental regulations like the TIER III and EURO VI wield a maximum of 10 mg/kg of Total Sulfur or ppm by weight in diesel oils. The maximum amount of 10 ppm is also included in the Chinese norms GB 19147-2013 for Diesel fuels and GB 17930-2013 for Gasoline, deriving from the CHINA 5 environmental program. The maximum allowable amount of sulfur present in fuels demonstrates a downward trend on global scale. This raises the importance of accurately measuring the total amount of sulfur in petro (chemical) products at trace level.