During the final aspiration, her pipette tip touched the side of the conical tube. A tiny speck of serum-rich residue—invisible, but chemically catastrophic—smudged the tip. She had to swap to a fresh one. That cost her 8 seconds.
Three minutes and fifty seconds. Ten seconds to spare. xfer serum free
"No," Elena said, not looking up from the eyepiece. "I did it myself." During the final aspiration, her pipette tip touched
With a 200-microliter pipette, she carefully, painfully slowly, removed the supernatant. She left a tiny film of liquid above the pellet—not enough to contain any serum, but enough to keep the cells from drying out. During the final aspiration
Then, disaster.