Method for quantitative determination of total base or acid number of oil

Abstract

The total base number of an oil sample of measured volume is determined by solvating the oil sample, adding a predetermined amount of acidic species to the solvated sample to react the acidic species with any basic species contained in the oil sample, extracting the remaining acidic species into an extractant phase, separating the extractant phase from the oil sample, and measuring the acidic species content of the extractant phase to determine the quantity of basic species in the oil sample. The same technique may be used to determine the total acid number of an oil sample by adding a predetermined amount of basic species to the sample and measuring the basic species content of the extractant phase. Apparatus comprising a test kit for carrying out the method comprises a sampling syringe (10) for drawing a fixed volume of sample oil, a reaction container (22) containing premeasured quantities of acidic species and solvent in first and second frangible ampules (28, 30) and a titration container (32) containing a pH indicator in a third frangible ampule (38). A titration syringe (50) contains a basic solution for titrating the extractant and bears graduations (55) which are scaled and numbered to indicate the total base number of the sample, and a cap (56) for securing the titration syringe (50) to titration container (32).