Since the reaction is dependent on the formation of water, check the acetic acid for moisture, if >0.1% it could cause variation in results. If you have changed the p-anisidine, is it a fresh lot? It needs to be stored in a dark bottle, 0-4 deg Celsius and then expect about a year of shelf life. A fresh solution in a 1 cm cuvette at 350 nm should have an absorbance

Dear Lance,

Everything you mentioned has been accounted for.

Yet, the results are still absurd.

Is the sample a crude or refined? Crude oils can be especially tricky due to particulate that will scatter the light and result in an artificially high result. Filtration through a Whatman #40 should be sufficient, however, it should be with nitrogen under pressure as gravity filtration and vacuum filtration will be too slow and vacuum filtration can result in changes in the sample due to loss of volatiles.

Is the result absurd because it is inconsistent (not reproducible?) or is there other characteristics that appear to demonstrate that the oil is high quality (not blended, contaminated or chemically or physically abused?) for example peroxide value, free fatty acid or iodine value.

Dear Lance,

The results as you mentioned are artificially high thus why I said they are absurd. They are consistent in their high value.

I conducted the peroxide value and the results turned out as they should be (low for fresh oil and high for rancid oil).

The oil is crude oil so you're feedback is highly valuable and appreciated. I will definitely try filtrating the oil as you recommended.

Thank you!

Best,

Maria

kindly help me with the SOP of p-Anisidine value

Pannan Dajams May be it helps

https://www.iffo.net/system/files/FOB12.PDF