How can I mix my vitamins with water, and still get every drop of the solution without losing any of the vitamins to the glass?

When I put my vitamins into water or juice their always seems to be a small amount left in the glass that I mix them in. If I continue to add water to the glass I eventually get most all of any trace amounts left in the glass, but it takes a while and a lot of drinking. Since I take these vitamins often does it matter that I miss these small amounts?