scope:

Specifies a colour-indicator titration method for the determination of acid or basic constituents in petroleum products and lubricants soluble in mixtures of toluene and propan-2-ol. It is applicable for the determination of acids or bases whose dissocation constants in water are greater than 10 ^-9; extremely weak acids or bases whose dissocation constants are less than 10 ^-9 do not interfere. Salts react if their hydrolysis constants are greater than 10 ^-9. The method is not suitable for measuring the basic constituents of many basic additive-type lubricating oils, for which ISO 3771 can be used.