I see a white substance floating on top of the sulfuric acid after a Kjeldahl digestion. Will this substance affect my results?

If you do the de-fat procedure using ANKOM XT4 filter bags, after you complete the Kjeldahl digestion, there will be a white substance on top of the resulting liquid. This substance is the PTFE coating on the XT4 filter bags. This substance will NOT impact your results.