Does low-flow sampling get representative samples of petroleum NAPLs in an inlet that is 10 meters below the water level?

When sampling a well that has NAPL present there is always the issue of: what are we sampling? If you are trying to get a sample of the NAPL, the only way you are able to do that is by using something like a bailer or some other type of grab sampler from the surface. But, if you are trying to get a sample of dissolved fraction in a well that has NAPL present, then you have another set of concerns because wells can tend to act as accumulators for NAPL. You could have several centimeters or more of petroleum NAPL present in a well but find that there is far or less than that in the surrounding formation because it accumulates in the well.  Because it’s present in the well and in contact with the water column, we can see concentrations in the water column, in the borehole, or in the screen zone that are essentially at or very close to the solubility limit of those contaminants in water. So, I generally try to avoid sampling dissolved fraction for wells that have NAPL.