[zhang2200]

I'm doing a preliminary experiment with acetonitrile, water, and soil. I add soil to a tube, add water, then add acetonitrile as 20, 40, 60, 80, and 100 percent of the solution. Controls contain the same proportions, but without soil. Assume that acetonitrile adsorbs strongly to soil, and that the density of acetonitrile is significantly lower than that of water.

Now, when acetonitrile adsorbs to the soil, is the density on top of the soil after mixing and centrifuging the samples going to be the same as the control, or greater?

I basically need a way to measure the concentration of acetonitrile after adsorption experiments. My HPLC is not set up for it, and I cannot afford a device that measures the dielectric constant. I can measure changes in density +/- 0.3 percent since I'm extremely skilled at measuring volumes. For example, if the density of water is 0.997, I can measure 0.997 grams with a 1 mL syringe +/- 0.0005 grams by hand.

[zhang2200]

I did some more research at the suggestion of a friend. It's better to measure changes acetonitrile concentration using a GAC with Nitrogen Phosphorus Detector, but I don't believe our laboratories have one. I'll ask around, but it would still be interesting to get some answers. This really isn't something I'm familiar with and I know it's simple for some of you.