Digital pipettes have become standard laboratory tools due to their high precision and traceability advantages. However, improper operation can easily lead to data deviation or equipment damage. This article explains from three aspects: operation process, skill optimization, and avoiding misunderstandings.
1、 Standardized operating procedures
Range setting
Rotate the adjustment knob to the target volume to avoid rapid rotation causing internal gear wear. For example, when moving 200 μ L of liquid, the range needs to be adjusted to align with the 200 μ L mark on the scale, and the display screen should be observed to confirm that the value is stable.
Suction head installation
Gently press the suction head vertically until it makes a "click" sound to ensure sealing. Do not insert diagonally or repeatedly tap, otherwise it may damage the suction cone and cause leakage. Experiments have shown that incorrect installation can result in a volume loss of 5% -10%.
Pre lubrication steps
Before suctioning, rinse the suction head 2-3 times with the target liquid to reduce the impact of surface tension. For example, when removing high viscosity solutions (such as glycerol), failure to rinse may result in actual volume deviation exceeding 15%.
Liquid absorption and discharge
Liquid suction: Immerse the suction head 2-3mm below the liquid level, slowly release the button to the first gear, and wait for 1-2 seconds for the liquid to fully enter the suction head.
Drain: Close the container wall tightly and slowly press the button to the second gear to drain the residual liquid. For micro pipettes (<10 μ L), keep the pipette tip in contact with the container wall for at least 3 seconds.
2、 Key operational skills
Angle control: Keep the pipette vertical (tilt angle<15 °), avoid the suction head from contacting the bottom or side wall of the container, and prevent liquid splashing or bubble formation.
Temperature balance: If there is a large temperature difference between the liquid and the suction head (such as a sample taken from a 4 ℃ refrigerator), it is necessary to let it stand at room temperature before transferring the liquid, otherwise thermal expansion and contraction will cause volume errors.
Speed matching: Adjust the operating speed based on the viscosity of the liquid. Low viscosity liquids (such as water) can quickly absorb liquid, while high viscosity liquids (such as serum) need to slow down to reduce wall adhesion.
3、 Common misconceptions and corrections
Misconception 1: Immediately drain the liquid after absorbing it
Problem: The liquid did not fully enter the suction head, resulting in insufficient actual volume.
Correction: After suctioning, stay for 1-2 seconds, especially when removing trace or high viscosity liquids.
Misconception 2: Mixing liquids with a digital pipette
Problem: Repeated blowing and hitting may introduce bubbles or change the liquid concentration, and may damage the piston.
Correction: When mixing, a dedicated oscillator should be used or mixed upside down.
Misconception 3: Long term use of the same measuring range without calibration
Problem: Frequent use of the same measuring range (such as 100 μ L) can cause gear wear and decreased accuracy in that area.
Correction: Regularly rotate the use of different ranges and calibrate according to ISO8655 standard every 6 months.
Misconception 4: Use immediately after high-temperature and high-pressure sterilization
Problem: After sterilization, there may be residual water vapor inside the suction head, which affects the accuracy of pipetting.
Correction: After sterilization, air dry or blow dry the suction head with compressed air before installation and use.
4、 Maintenance and upkeep
Daily cleaning: Wipe the casing with 75% ethanol to avoid using organic solvents (such as acetone) to corrode the display screen.
Regular lubrication: Apply special silicone grease to the piston every 3 months to reduce friction.
Storage environment: Vertically placed in a non corrosive gas environment, avoiding direct sunlight that may cause aging of the display screen.
Summary: Proper use of digital pipettes requires a combination of standardized procedures, skill optimization, and regular maintenance. By avoiding common misconceptions, the repeatability of experiments can be significantly improved, the lifespan of equipment can be extended, and the reliability of scientific research data can be guaranteed.