Another important parameter indicative of the
quality of BioDiesel is Total Acid Number (aka TAN or
Neutralization Number), expressed as the number of
milligrams Potassium Hydroxide required to neutralize
one gram of sample. This test is carried out as a
Potentiometric Titration described in standard test
methods ASTM D664, ISO 6619, and JIS K2501. The TAN
of a sample can also be used to calculate its Free Fatty
Acid content – a key process parameter to monitor in
BioDiesel production, where FFAs are converted to Fatty
Acid Methyl Esters (FAMEs). When performing
Potentiometric Titration to determine Acid number it is
recommended to use an Automatic Potentiometric
Titrator in order to simplify running the test while
minimizing human error. The Titrant used in this test is 0.1
mol/L of KOH 2-propanol solution. And the Mixed
Solvent to be titrated is a 500:5:495 ratio of Toluene, Pure
Water, and 2-Propanol respectively.