4
11. Allow the plunger to return to the up position.
12. Discard the tip by depressing the tip ejector button. A
fresh tip should be used for each sample to prevent
sample carryover.
Tip Selection
■
Tips must seal properly on the shaft to assure an air-
tight seal and avoid leaks or poor accuracy.
■
Tips must be soft and flexible so that the shaft is not
scratched or worn prematurely.
■
Tips must be free from microscopic flash and particu-
lates. Flash gives poor precision and accuracy.
■
The tip orifice must be the correct size, and orifice size
and geometry must be consistent from tip to tip. Other-
wise, accuracy and precision will be affected.
■
Interior and exterior surfaces must be clear, smooth,
and hydrophobic to avoid retention of liquid. Too much
retention results in poor accuracy and reproducibility.
Figure 2
Operating Pipetman
pipetman rev I 9/13/00 3:12 PM Page 6
