Ti Application Note No.
Acid number (TAN) of mineral oils
Determination of the acid number (TAN) of mineraloils by nonaqueous, potentiometric titration with TBAOH using the (built-in) differential amplifier and three-electrode technique. Mineral oilsample
Sample: Sample Preparation:
Instruments and Accessories: 702, 794, 798 or 799 Titrino or 808, 809, 835 or 836 Titrando with6.2129.010 differential amplifier, 6.0431.100 Pt Titrode and 6.0729.100 Ag/AgCl reference electrode [inner and bridge electrolyte c(LiCl) = 2mol/L in ethanol] Analysis: Dissolve the sample (the sample size depends on the TAN expected) in 100 mL solvent* and titrate with c(TBAOH) = 0.1mol/L in isopropanol using the MET mode. * Solvent mixture: 500 mL toluene + 495 mL isopropanol + 5 mL dist. water Calculation: TAN (= mg KOH /g sample) = (EP1 – C01) * C02 * C03 / C00 EP1 C00 C01 C02 C03 Remarks: = = = = = titrant consumption for the sample in mL sample mass in gtitrant consumption for the blank (solvent) in mL 0.1 (concentration of the titrant in mol/L) 56.106 [M(KOH in g/mol]
– Condition the PtTitrode by immersing it in the solvent for 50 min. – After three titrations immerse the Pt Titrode in dist. water for 5 min. – Because of the verylow TAN of our mineral oil sample in this case a sample mass of 20 g was used. Result: AVG(3) = 0.006 ± 0.001 mg KOH / g sample
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