I am using soxhlet extraction to extract fat from fish muscles using petroleum ether. After extraction, the ether is recovered by distillation. We are facing the following issues for which we need some guidance.
1. When a little amount (10 ml) of ether has left in the flask, we evaporate it on hot plate, but even this small amount of ether didn't remove even for hours even though it remain boiling.
2. The extract that is obtained is dark brown in color and still contain some liquid that doesn't remove. Is this liquid is due to presence of oily fraction in fish lipids?.
Any help in this regard will be highly appreciated.