ISO 4265:1986

Petroleum products — Lubricating oils and additives — Determination of phosphorus content — Quinoline phosphomolybdate method

The method used is applicable to products containing any of the phosphorus compounds in normal use and having contents between O,OO5 and 1O,O % (m/m). The method is free from most interferences because the high insolubility of the quinoline phosphomolybdate precipitate leads to constant composition and freedom from most adsorbed or occulated impurities, especially from cations which would otherwise interfere in the subsequent titration of the precipitate.