That depends on the sizes. The article says > Only when the authors tested upwards of five drops combined (60 to 100 microliters) were they able to get accurat

That depends on the sizes. The article says > Only when the authors tested upwards of five drops combined (60 to 100 microliters) were they able to get accurate results. That still sounds pretty low volume to me. I can't read the actual article, so I can't comment in much more detail (also, I'm not a biologist).