Micropipette is a core tool in molecular biology, clinical testing and chemical analysis laboratories. The accuracy of its operation directly affects the reliability of experimental data. However, many researchers make mistakes during use, which may lead to reduced pipetting accuracy, equipment damage, and even experimental failure. This article will systematically sort out the operations that must not be done when using micropipette, covering key links such as tip selection, pipetting skills, maintenance and special liquid handling, to help experimenters avoid common mistakes and ensure the accuracy and repeatability of experimental data.
Contents
1. Incorrect tip installation and use
2. Incorrect pipetting operation techniques
3. Improper liquid handling methods
4. Incorrect equipment maintenance and storage methods
5. Absolute taboos when transferring special liquids
6. Summary and best practice recommendations
1. Incorrect tip installation and use
1.1 Absolutely not: knocking the tip hard
Many experimenters are accustomed to knocking the pipette to ensure that the tip is firmly installed. This practice will seriously damage the sealing of the pipette handle, resulting in leakage or decreased airtightness.
Correct approach: Insert the pipette vertically into the tip and gently rotate it half a circle to fix it.
1.2 Never: Use mismatched tips
Different brands of pipettes and tips may have compatibility issues. Using mismatched tips will result in:
Insufficient airtightness, affecting pipetting accuracy.
Liquid residue, increasing the risk of cross-contamination.
Correct approach: Choose original or certified tips (such as microtips from IVD Consumable Supplier).
1.3 Never: Lay the pipette flat with liquid
Putting the pipette tip flat with liquid in it will result in:
Liquid backflow into the piston system, corroding internal components.
Rusting of the spring, affecting the service life of the pipette.
Correct approach: Use a pipette stand to place it vertically, or empty the tip in time.
2. Incorrect pipetting techniques
2.1 Never: Quickly release the piston to absorb liquid
Releasing the piston suddenly will result in:
Liquid is sucked in too quickly and may rush into the pipette, corroding the plunger.
Bubbles are formed, affecting the accuracy of pipetting.
Correct method: Slowly and steadily release the thumb to ensure that the liquid is sucked in at a uniform speed.
2.2 Never: Tilt the pipette to absorb liquid
Tilting the pipette more than 20° during aspiration will result in:
Inaccurate volume of aspirated liquid (error can reach 0.7%).
Liquid adheres to the outer wall of the pipette tip, increasing the risk of contamination.
Correct method: Keep the pipette vertical and immerse the pipette tip 3-5mm below the liquid surface.
2.3 Never: Use the second gear to aspirate liquid directly
Some experimenters press directly to the second gear to aspirate liquid to speed up the operation, but this will result in:
Excessive liquid aspiration, exceeding the set volume.
Liquid enters the pipette and damages the piston system.
Correct approach: first press the first gear to aspirate liquid, and then use the second gear to blow out the residual liquid when discharging liquid.
3. Improper liquid handling methods
3.1 Never: use a large-range pipette to aspirate a small volume of liquid
For example, using a 1000μL pipette to aspirate 10μL of liquid will result in:
The error increases by 3 times (from ±0.8% to ±2.5-3%).
The liquid residue increases, affecting the repeatability of the experiment.
Correct approach: select a pipette with matching range (optimal range: 35%-100% of the maximum range).
3.2 Never: use a pipette to mix liquid
Some experimenters use a pipette to repeatedly blow and aspirate to mix liquid, but this will:
Produce aerosols and increase the risk of contamination.
Accelerate the wear of the tip and reduce the sealing.
Correct approach: Use a vortex oscillator or dedicated mixing equipment.
4. Incorrect equipment maintenance and storage methods
4.1 Never: Use organic solvents (such as acetone) to clean the pipette
Strong solvents such as acetone will:
Dissolve the plastic parts inside the pipette, causing the seal to fail.
Residual solvents will contaminate subsequent experiments.
Correct method: Clean with 60% isopropyl alcohol or distilled water, dry and apply silicone grease for lubrication.
4.2 Never: Fail to adjust to the maximum range during long-term storage
The pipette is in a small range state for a long time, which will cause:
Spring fatigue, affecting the rebound performance.
Piston stuck, reducing pipetting accuracy.
Correct method: After each use, adjust the range to the maximum value to let the spring return to its original state.
5. Absolute taboos when pipetting special liquids
5.1 Never: Directly absorb highly volatile liquids (such as ether)
Vapor from volatile liquids will:
Enter the interior of the pipette and corrode the piston system.
Change the internal air pressure, resulting in inaccurate pipetting.
Correct approach: Use a positive-displacement pipette or low-retention pipette tips.
5.2 Never: Directly pipette hot liquids (>70°C)
Hot liquids can:
Generate steam and damage the internal seal of the pipette.
Cause the pipette tip to deform and affect airtightness.
Correct approach: Wait until the liquid cools to room temperature before pipetting, or use a heat-resistant pipette tip.
6. Summary and best practice recommendations
6.1 Key taboos review
Do not knock the pipette tip or use an incompatible pipette tip.
Do not pipette quickly or tilt the liquid.
Do not use a large-range pipette to pipette small volumes of liquid.
Do not mix the liquid by blowing with a pipette.
Do not use strong solvents such as acetone to clean the pipette.
Do not directly pipette highly volatile or hot liquids.
6.2 Best practice recommendations
✔ Choose high-quality pipette tips (such as microtips from IVD Consumable Supplier).
✔ Calibrate your pipette regularly (1-2 times a year).
✔ Proper cleaning and storage extend the life of your equipment.
Following the above specifications can significantly improve pipetting accuracy, reduce experimental errors, and ensure the reliability of your scientific research data!
FAQ
1.Why must a pipetman be held vertically when the tip is filled with liquid?
To prevent liquid spillage from the tip, it is essential to hold the pipetman vertically while filling it with liquid. The force of gravity can then be utilized to control the rate at which the liquid enters the tip, ensuring that it does not overflow. Holding the pipetman vertically also enables the easy identification and removal of air bubbles from the tip before dispensing the liquid. Therefore, it is crucial to maintain a vertical orientation when filling the pipetman tip with liquid to ensure accurate and precise sample transfer.
2.Why do we use a pipette in titration when we can use a measuring flask?
A pipette is used in titration instead of a measuring flask because it can measure a precise volume of liquid with high accuracy. Titration involves the addition of a precise volume of a titrant solution to a solution of unknown concentration until a chemical reaction reaches completion, and a color change or other signal indicates the endpoint. The titrant solution is added dropwise until the endpoint is reached, and the volume of the titrant solution used is measured.A measuring flask, on the other hand, is designed to measure a fixed volume of liquid, which is not as precise as the volume measured using a pipette. Using a measuring flask to measure a precise volume of titrant solution can lead to inaccurate results, which could affect the accuracy of the titration results.Pipettes are also available in a range of volumes, making them suitable for measuring the exact volume of titrant solution needed for a titration. Moreover, pipettes are designed to deliver precise and accurate volumes of liquid with minimal variability, making them an ideal choice for titration, where precise measurements are essential.In summary, a pipette is used in titration instead of a measuring flask because it can accurately measure precise volumes of liquid, which is critical for obtaining accurate and reliable titration results.