Pipetting Procedure

Serological – to deliver (TD)/blowout (frosted tip), calibrated to the tip of pipet, held in a vertical position allowing the tip to remain in contact with the side of vessel.

Mohr – to deliver (TD)/don’t blowout, drained from beginning calibration line to end calibration line, held in a vertical position, tip does not touch the receiving vessel side.

Both are measuring pipets and can deliver different amounts of liquid.

Volumetric – to deliver (TD) pipet, measures only one volume, accurate, in order to deliver full amount, the tip must touch the side of the receiving vessel, held on an angle, with pipet kept in a vertical position.

Supplies

1. Volumetric pipettes (various sizes)
2. Graduated pipettes (various sizes)
3. Safety Bulbs
4. Kimwipes
5. Distilled water

Instructions

Correctly select and use various types of manual pipettes. Read the list of required equipment and supplies and the procedural steps.

Follow the procedural steps in the exact order.

1. Put on gloves and eye protection
2. Assemble equipment and supplies
3. Check the pipette for any cracks or broken pieces
4. Hold the pipette lightly between the thumb and last three fingers, leaving the index finger free.
5. Place the tip of the pipette well below the surface of the liquid to be pipetted.
6. Using the bulb, carefully draw the liquid up into the pipette until the level of liquid is well above the calibration mark.
7. Quickly cover the suction opening at the top of the pipette with the index finger.
8. Wipe the outside of the pipette dry with a piece of gauze or tissue to remove the excess fluid.
9. Hold the pipette in a vertical position, with the delivery tip against the inside of the original vessel. Carefully allow the liquid in the pipette to drain by gravity until the bottom of the meniscus is exactly at the calibration mark. Do not entirely remove the index finger from the suction-hole end of the pipette; roll the finger slightly over the opening, allow slow drainage to take place.
10. While still holding the pipette in a vertical position, touch the tip of the pipette to the inside wall of the receiving vessel. Remove the index finger from the top of the pipette to permit free drainage.
11. Volumetric – Do not blow out
12. Serological – Blow out
13. Mohr – Do not blow out
14. Remove the pipette from the receiving vessel and put in pipette washer.
15. Discard used kimwipes and other contaminated supplies into the bench top biohazard container.
16. Put glassware in the basin with soapy water.
17. Clean work area with disinfectant solution