[Sojourner26]

Is there a reliable reference specifying temperature conditions for hydrodistillation? We have students in my college doing a study on black seed oil (Nigella sativa). To determine the volatile constituents, they performed hydrodistillation and gave to me the sample for GC-MS. The resulting chromatogram showed peaks for methyl esters. They shouldn't be detected as methyl esters are indicative of the presence of fatty acids. I referred the matter to my Head who has a PhD. She told me the detection of methyl esters is normal. I was in disbelief as I had 3 references showing volatiles are aroma compounds. Fatty acids are classified as fixed oil components. I investigated further and found out that the students were using a heating mantle with no power control. The mantle's temperature went as high 239 °C for heating up to 3 hours! I'm bringing this matter up as my reference papers don't mention the temperature setting for the heating mantle.

Comments would be much appreciated.