Determn. of carbonate basicity, esp. of oils - by treating with acid and IR analysis of carbon di:oxide released

摘要

Determn. of the carbonate basicity of aq. or organic media (esp. lubricant additives and new or used oils) is carried out by (a) treating a soln. of the test sample with excess non-oxidising mineral acid in an inert atmos, and (b) measuring the amt. of CO2 released by measuring the IR absorption intensity in the C-O vibration band of CO2. Oil samples are pref. dissolved in an aromatic solvent, esp. toluene. The acid is pref. 13-18N H2SO4. The method is capable of determining carbonate concncs. ranging from 1 ppm to several percent with a reproducibility better than 3% an analysis times of less than 10 min. It gives a more accurate measure of carbonate-derived total base no. (TBN) then the methods of ASTM D 2896 and D 664.