Intracellular analysis is much easier and valuable as well.
Read about it at the site below. Dear Dr B., This is a new one on me. The link you provided was very helpful. I knew about the challenge test but have not used it so far. Sometimes he got up in the middle of the night and ran to the hospital to wait in the corner of the operatory hoping the surgeon would feel he could step back for a moment to allow Burton to take his samples.