D-4
Appendix D
Pipetting Techniques
The following example describes an instance when
the above 8-step procedure is required. An operator
needs to dispense 50 µL of reagent into each of 20
test tubes. The tube-to-tube consistency of reagent
volume is critical. However, in order to save time,
the operator wishes to make a single 1 mL
aspiration from the reagent reservoir and then
make multiple dispenses. If the 8-step procedure
was not used, the last aliquot of the 20 dispenses
would be more diluted than the others. If the
procedure was used, the requirements of the
routine and the operator’s desire to save time could
both be met. (Recommended volumes in this
example are 15 µL air gaps and 100 µL excess
volume in Step 4.)