If you pour off the water/naptha into something like a mayonnaise jar that gets smaller at the top that will make for a thick layer of naptha. You can suck the naptha up into the turkey baster. If you suck some MHRB/water up into the turkey baster you can just hold it with the tip just below the surface of the naptha and the water/mhrb will fall out. Put the naptha into something like a baby food jar and then put it into the freezer and you should have crystals precipitate out. The small amount of naptha that you can't get off of the top you can pour off into something like a graduated cylinder to make it easier to separate.