Subject: How do you measure the amount of oil in sand after trying to clean it up?

I am doing an experiment mixing sand and cooking oil and then trying to 
clean the oil up using different materials.  Is there a scientific way to 
measure the amount of oil in the sand after trying to clean it up?  I tried 
finding an answer using searches but couldn't find anything.  I thought of 
weighing the sand but don't think this would be entirely accurate because 
the items I try to clean the oil spill up with will become mixed with the 
oil and sand.  Thank you.

Re: How do you measure the amount of oil in sand after trying to clean it up?