IP 471: Determination of the water content of distillate petroleum products - Potentiometric Karl Fischer titration method

Overview:

Scope

This method specifies a method for the direct determination of water in fuel oil using a potentiometric Karl Fischer titration procedure over the range 0,05% (m/m) to 2,00% (m/m) in fuel oil containing less than 0,05% (m/m) of either mercaptan sulfur or sulfide ion sulfur or both. It covers the range 0,02% (m/m) to 2,00% (m/m) water in fuel oil containing less than 0,005% (m/m) of either mercaptan sulfur or sulfide sulfur or both.

NOTE 1 Water in light and middle distillate petroleum products may be determined using IP 438 or IP 439.

NOTE 2 A number of substances and classes of compounds associated with condensation or oxidation-reduction reactions interfere in the determination of water by Karl Fischer titration. However, the only likely interferences in fuel oils are mercaptans and ionic sulfides. At levels of less than 0.05% (m/m) as sulfur the interference for these compounds is insignificant when determining water in the range 0.05% (m/m) to 2.00% (m/m). Other organic sulfur compounds commonly present such as sulfides, disulfides and thiophenes do not interfere.