Testing Biodiesel or Methanol For Soap Levels Using A Soap Test Kit

[redblue18700]

I add the bromophenol blue turns yellow when i add it to the isopropanol.. not dark yellow, but it's not blue at all (not greenish either). no bioD added yet. same with acetone as solvent.

only when i add tiny drops of naoh solution does it turn blue-very blue. this indicates the indicator is working... but the alcohol solution indicates yellow to start. can't get this to be otherwise.

[UtahBiodiesel]

@redblue18700 That means your Isopropyl Alcohol is acidic. You need to get new Alcohol. However, by "blanking the solution" by getting it to turn slightly blue with some NaOH solution is fine.

[UtahBiodiesel]

@redblue18700 You might need to swap out your Isopropyl for some newer stuff. It sounds like it might be slightly acidic; which can throw off the test.