Sources of Error in Pipetting

1. Failure of properly align the meniscus with the volume mark.
   
   
2. Parallax error: Your eye must be level with the volume mark and the pipet vertical. If you are looking up at the pipet, the meniscus will be too high when it appears to align with the mark. It you are looking down at the pipet, the meniscus will be too low when it appears to align with the mark.
   
   
3. Forcing the solution out of the pipet causes too much to be delivered.
   
   
4. Using a dirty pipet causes too little or contaminated solution to be delivered. Leaving little droplets behind on the walls (except for the small amount in the tip) causes too little solution to be delivered.
   
   
5. Forcing the pipet into the bulb usually causes liquid to be sucked into the bulb. This contaminates the bulb which must then be thoroughly rinsed and dried.
   
   
6. Allowing the tip of the pipet to rise above the liquid in the container usually causes the liquid to be sucked into the pipet bulb.
   
   
7. A broken or chipped pipet can reduce the amount of liquid held after transfer. This causes too much liquid to be delivered.
   
   
   
   

Pipet Menu