Very small pipetting volumes increase relative error. If a reagent requires sub-microliter addition, prepare an intermediate dilution or increase master mix volume when the protocol allows it.
Dead volume
Dead volume is material that remains in tips, tubes, reservoirs, or corners. Overage protects against dead volume and small handling losses, especially when many wells are filled from one mix.
Pre-wetting
Pre-wetting the tip can improve consistency for some liquids. Viscous reagents, glycerol-containing enzymes, and detergents may need slower aspiration and dispensing.
Repeatability habits
Use the same pipetting angle, depth, speed, and touch-off behavior across replicates. Consistency is often more important than moving quickly.
Planning checklist
- Avoid sub-microliter additions when possible.
- Add overage for master mixes.
- Mix stocks before pipetting.
- Use the right pipette range for the volume.
- Record intermediate dilutions clearly.
Why it matters
Pipetting error can create false biological differences, weak reactions, and inconsistent controls. Reducing it improves the value of every calculation downstream.