Note: when doing a titration, the solution in your beaker should be constantly and gently stirred. Always avoid contamination by keeping your lab area clean and lids on all your containers.
To accurately determine the acidity (FFA content) of your oil, you need to accurately know the strength of your base solution. It is nearly impossible to measure out a small amount of the base (like sodium hydroxide) to mix into a solution with a high degree of accuracy. One of the problems encountered in trying to do this, is the fact that NaOH quickly absorbs water and CO2 out of the air. This makes the compound both heavier and weaker. Steps 2-6 (above) have allowed you to determine the strength of the basic solution that you are using to titrate your oil. To double check the strength of your base solution, repeat steps 2-6 to make sure the results compare.
Because a basic solution will lose strength over time, whenever, you have a day that you plan to titrate some oil or fuel, start by employing steps 2-6 to find the strength of your base solution. If it has degraded somewhat, there is no need to worry. Simply use the new number that you have for “true grams of NaOH/liter” in step 5 below.
Now to actually titrate your oil (or finished biodiesel if you are testing for TAN):
To process this in the BioPro™ 190, you should have less than 5% FFA To pass TAN test for finished fuel you should have less than .28% FFA.
For greater accuracy on the TAN test you can use 50ml of Isopropyl (step 1), 10 ml of fuel (step 3), and divide by 12.8 instead of 1.28 (step 5).