3 ml of solution, about 50 tests.
Take a common translucent water drinking glas and place it upside down. Place now one drop of the Red-E-Meter cocaine testing solution on the bottom and add a knife point of the sample into the drop.
All immediately turning blue is cocaine, all the rest is cut-off.
After short practice everybody is able to perform this test and to evaluate the quality of the sample. Avoid hurry and use bright light with white background. The ratio between blue and non-blue material equals the percentage.
e.g. 1/2 turning blue , and 1/2 does not, there is ca. 50% Cocaine in the sample.
Even different cuts can be determinded according to their specific crystal form.