Choose a pipette for the volume and liquid, then transfer water with a repeatable hand position and documented checks.
Field diagramControlled liquid transfer
Estimated reading
8 min
Estimated practice
15 min
Equipment
Adjustable air-displacement micropipette, compatible tips, clean water, receiving tubes, rack, timer, and a balance only if an approved gravimetric check is available.
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Objective
By the end, you can:
Match a pipette range and tip to a planned volume and liquid.
Perform forward pipetting with consistent stops, immersion, speed, and tip contact.
Recognize when a transfer is suspect and record the deviation rather than silently correcting it.
Why selection is part of measurement
A pipette does not make every volume equally trustworthy. First write the target volume, its unit, and the liquid. Select a device whose published operating range contains that volume; near the middle of a range is often easier to control, but the manufacturer’s instructions and your method decide what is acceptable. Use a compatible, undamaged tip. A transfer from a clean water stock into a clean tube is a bounded practice exercise. It does not qualify you to handle samples, volatile liquids, viscous liquids, corrosives, or biological material.
Forward pipetting uses the first plunger stop to aspirate the set volume and the second stop to empty the tip. The technique depends on a slowly returning plunger, a nearly vertical tip, controlled immersion, and a consistent dispense against the vessel wall. Pre-wetting the tip can reduce evaporation effects in air-displacement systems; the Eppendorf operating manual recommends aspirating and dispensing the liquid one to three times before the measured uptake. The point is consistency, not a ritual number detached from the instrument manual.
Use a new tip when identity, cleanliness, or carryover matters.
Keep the pipette upright during aspiration and avoid touching the liquid surface with the shaft.
Do not infer accuracy from a smooth-looking plunger; verify with a defined method when the result matters.
A controlled transfer
Practice with water and a single planned volume. Put the source and destination at a comfortable height, label the destination before starting, and write down the pipette ID, set volume, tip type, operator, date, and any instrument-specific temperature or pre-wetting instruction. A useful checkpoint asks what you observed: bubbles, a droplet outside the tip, an unstable meniscus, or a missed stop. Each observation is data about the transfer, not an embarrassment to hide.
Worked example
One recorded transfer
A learner uses pipette P-02, set to 1.00 mL, with a compatible tip and clean water at room conditions. The first transfer shows no bubble; the second has a droplet on the outside of the tip before dispense.
01Tube W1: P-02, 1.00 mL, no visible deviation.
02Tube W2: P-02, 1.00 mL, external droplet observed; transfer marked suspect and repeated with a new tip.
03Conclusion: the repeated tube is usable for practice comparison; the suspect attempt remains in the raw record.
Materials
Set out what you need.
Clean water labeled as practice material
Compatible disposable tips
Two labeled clean tubes
Notebook or raw-data sheet
Safety & stop conditions
Pause if the work no longer fits the plan.
Use only clean water for this beginner exercise; do not substitute unknown samples or chemicals.
Follow the instrument manual, keep tips pointed away from people, and stop if liquid enters the pipette body.
Discard tips in the local designated waste container and clean a spill using the site’s approved water-spill procedure.
Method
Work through the steps.
01
Define the transfer
Write the target, unit, source identity, destination identity, and acceptance rule before touching the pipette. This turns a hand movement into a traceable measurement.
02
Inspect and set
Confirm the range, fit a compatible tip, and set the volume without forcing the adjustment beyond its limits. Check that the tip is seated without cracking it.
03
Condition the tip
With water, aspirate and dispense one to three times if the manufacturer’s instructions call for pre-wetting. Keep the hand motion slow enough to avoid bubbles.
04
Aspirate
Press to the first stop, immerse the tip to the manual’s recommended depth, and let the plunger return slowly while the pipette remains vertical. Pause briefly, then withdraw without scraping the wall.
05
Dispense and document
Touch the tip to the receiving-wall, press to the first stop, wait for drainage, then press to the second stop and withdraw while still holding the plunger. Record observations and change the tip when the method requires it.
Checkpoints
Observe, record, investigate.
The pipette range contains the target and the set volume is visible before aspiration.
The tip has no external droplet or visible bubble and the plunger was released slowly.
The destination identity, pipette ID, set volume, and any deviation are in the notebook.
A repeated practice transfer uses the same immersion depth, hand position, and dispense contact.
Common mistakes
Correct the process, preserve the record.
The tip is immersed deeply and liquid rises into the shaft.
Stop, follow the instrument cleaning guidance, and repeat with the manual’s immersion depth. Do not continue using a contaminated pipette.
A bubble appears during aspiration.
Treat that transfer as suspect, expel safely into the source if allowed, inspect the tip fit, slow the plunger, and record the event.
The operator presses straight to the second stop during aspiration.
Reset and use the first stop for uptake; the second stop is the blow-out portion of forward dispensing.
A different pipette is substituted without a record.
Record the new ID and confirm that its range, tip, and method are appropriate before combining results.
Practice
Water-transfer repeatability log
If you have a permitted pipette whose published range includes 1.00 mL, set it to 1.00 mL and transfer water into three labeled tubes. Otherwise use the W1/W2 records in the worked example below and annotate the expected checkpoints without operating equipment. This is a technique exercise, not evidence that the pipette is calibrated.
What did you hold constant?
Which transfer, if any, had a visible deviation?
What one change would you test in a second round?
If no balance is available, which observations can you still report honestly?
01Why is a pipette’s range relevant to a target volume?
Answer: The published range defines where the device is intended to operate; a target outside it has no justified volume claim.
02What is the first stop used for in forward pipetting?
Answer: It is used for the measured aspiration and the initial dispensing stroke; the second stop completes emptying the tip.
03A bubble is visible after aspiration. Should the result be averaged away?
Answer: No. Mark that transfer suspect, follow the method’s repeat rule, and retain the original observation in the raw record.
04Why might pre-wetting help an air-displacement pipette?
Answer: It conditions the air cushion and can reduce evaporation-related volume effects, especially for small volumes; the instrument manual controls the exact practice.
