DescriptionTitrimetric determination of total acid number (TAN) in crude oil. Protocol is applicable to crude oils of medium acidity (approximately 0.5 mg KOH\/g). Sample and reagent volumes should be adjusted if the TAN value is expected to be outside of this range. InstrumentationThe analysis is carried out using a slightly modified version of ASTM 664 using a SI Analytics TitroLine 7750 (see attached documents for details of the original procedure). ReportingTAN values are reported in milligram of potassium hydroxide per gram of sample (mg KOH\/g).Quality control (QC) \/ system suitability test (SST)A synthetic oil containing a mixture of C13, C15 and C17 linear fatty acids (in 80:20 hexadecane:toluene) corresponding to to 0.5 mg KOH\/g is prepared and analyzed with each batch (maximum 6 oils). The value should be within 10% of the true value.