A way of checking your solution/solvent is use of a Refractometer, temperature compensated. These can give a fairly accurate reading of solutions. Leica, Inc., may be able to help. Leica manufactures refractometers. We use a refractometer to measure the percent concentration of our solvent section and rinse stages of our semi-aqueous cleaner. Leica telephone number is (716) 891-0123. Address is shown below. Leica Inc. Microscopy & Scientific Instruments Division P.O. box 123 Buffalo, NY 14240-0123