Epigenetic library screening: a) Raw droplet traces of the screening. The upper trace is the reaction product H3K9, and the lower one is the isotope-labeled internal standard H3K9*. The first 3 sets are negative controls at the beginning, in the middle, and at the end of the assay plate, respectively. b) Enlarged view of a control, reaction containing suramin, and some other test reactions droplets. c) The final analysis of the screening. Each bar is the averaged H3K9/H3K9* of an assay. The negative control (green) is normalized to 100% enzyme activity. Four reactions showed that the enzyme activity was lowered by more than 50% (n=3).