(Equivalent Test Methods: IP 149 and ISO 4265)
TEST SUMMARY
This test method is applicable in the range 0.005 to 10.0 mass % of phosphorus in unused lubricating oils and additive concentrates. It should be applicable to filtered used oils also; but no study on this has been done. The sample is ignited with an excess of zinc oxide whereby phosphorus is converted to phosphate. The residue is dissolved in hydrochloric acid, and any sulfide formed is oxidized with potassium bromate. Phosphorus is then precipitated as quinoline phosphomolybdate and determined volumetrically by addition of excess standard alkali and back titration with standard acid.
TEST PRECISION
Where X is the average of two results.
The bias of this test method is not known.