A pipette is a tool used in experimental operations. For experts, the most important thing is to minimize experimental errors and achieve good reproducibility. Therefore, it is important to use the pipette correctly to avoid losing out on the bigger picture.
1、 Six parts of liquid transfer

1. Install the suction head
Press down firmly on the handle of the pipette and rotate it slightly as needed.
Incorrect operation: Strike the suction head forcefully. This method can cause damage to the suction head and even wear of the pipette handle, thereby affecting its sealing performance.
2. Range setting
Before operation, please select the correct pipette. The pipette can operate within the range of 10-100%, but operating at 10% requires high pipetting skills. Therefore, it is recommended to operate within the range of 35-100%.
Range adjustment: When adjusting from a small range to a large range, rotate continuously in the direction of the desired range, and then return to the desired range when the rotation exceeds 1/3 of the desired range. When adjusting from a large range to a small range, directly rotate continuously to the desired range.
3. Moisturizing and washing
Repeat the suction and drainage of the same sample two to three times, and rinse to provide the same contact surface for each subsequent suction, ensuring consistency in the operation.
Attention: Do not rinse with high or low temperature liquids!
4. Dip angle of suction head
When absorbing liquid, try to maintain a vertical position and the tilt angle should not exceed 20 °.

5. Depth of immersion of suction head

6. Suction head immersion time
After suctioning, keep it in the liquid surface for one second before gently moving the pipette tip away, which is particularly important for large capacity pipettes or for suctioning viscous samples.
7. Liquid absorption speed
Uniform and continuous pipetting, control the pipetting speed well. If it is too fast, it may cause liquid spray, liquid or mist to rush into the interior of the pipette, contaminating components such as the piston.
8. Drainage and Blowing
First, press the piston to the * gear to drain the fluid, pause briefly, and then press it to the second gear to blow the fluid.
There are four ways to drain:

9. Hand temperature
The pipette should not be held in the hand for a long time. When not in use, hang it on a stand or hang it in the hand to dry.

2、 Tips for using a pipette
1. Factors affecting the accuracy of the pipette
(1) Temperature: When the room temperature is low, the hand temperature is high, causing the air to expand and errors often occur when inhaling cold solutions
(2) Airtightness: The joint between the tip and the gun body, as well as the long-term wear between the cylinder inside the gun, can cause errors
(3) Suction speed: It can easily cause bubbles to form inside the tip and contaminate the nozzle
(4) Evaporation of reagents: When absorbing highly volatile reagents, steam enters the nozzle, increasing the internal pressure. As a result, when the liquid is squeezed out, the pressure increases, leading to errors. Solution: Repeat suction 4-5 times to improve.
2. Precautions for use
(1) When sucking liquid, be sure to slowly and steadily release your thumb, and never suddenly release it, to prevent the solution from being sucked in too quickly and rushing into the liquid extractor, corroding the plunger and causing air leakage.
(2) To achieve high accuracy, the suction head needs to aspirate the sample solution once in advance, and then formally transfer it, because when suctioning serum protein solution or organic solvent, a layer of "liquid film" will remain on the inner wall of the suction head, resulting in a small discharge volume and errors.
(3) Liquids with high concentration and viscosity can produce errors. To eliminate these errors, the compensation amount can be determined through experiments. The compensation amount can be set by adjusting the knob to change the reading window.
(4) The method of using an analytical balance to weigh and calculate the weight of pure water taken can be used to calibrate the liquid extractor. 1mL of distilled water weighs 0.9982g at 20 ℃.
(5) The method of repeatedly hitting the suction head to tighten the pipette is highly undesirable, as long-term operation can cause internal components to loosen and damage the pipette.
(6) Do not use a pipette without a suction head.
(7) Please pay attention when setting the range? Rotate to the desired range? Is the number clearly displayed in the window? The set range is within the range of the pipette. Do not turn the button out of the range, otherwise it will get stuck in the mechanical device and damage the pipette.
(8) The pipette is strictly prohibited from sucking liquids with strong volatility and corrosiveness (such as concentrated acid, concentrated alkali, organic matter, etc.).
(9) It is strictly prohibited to use a pipette to blow and mix liquids.
(10) Do not use a large range pipette to transfer small volumes of liquid, as this may affect accuracy. Meanwhile, if a large amount of liquid outside the measuring range needs to be removed, please use a pipette for operation.
3、 Incorrect operation and handling methods of pipette
As the most commonly used manually adjustable precision pipette in liquid operations, some incorrect operations during use can cause errors in the operation itself, and some can cause damage to the machine. Here is a brief summary:
Error: When assembling the suction head, repeatedly impact it with a pipette to tighten it
Correct: Insert the suction head, gently rotate left and right, and tighten the suction head
Analysis: Impact can cause loosening of the internal gear combination of the pipette, and long-term operation can affect the performance of the pipette.
Error: The suction head does not match the pipette, affecting airtightness. Correct: Choose a suction head that matches the pipette and has quality assurance
Analysis: The mismatch of the suction head is mainly manifested as its impact on airtightness. It will directly affect the performance of the pipette, and usually the pipetting operation will be less than the set amount.
Error: When suctioning, tilt the pipette to aspirate
Correct: Vertical suction
Analysis: A tilted state can cause changes in the pressure surface. It will affect the accuracy of liquid transfer.
Error: When the suction head contains unplugged liquid, place the pipette flat on the desktop
Correct: Hang the pipette vertically on the pipette holder
Analysis: The suction head contains untreated liquid, and after the pipette is placed flat, the liquid may flow into the interior of the pipette body, which can affect the internal components of the pipette and cause serious damage, poor pollution, and other situations.
Error: Using a large range pipette to transfer small volumes of liquid
Correct: The volume of the pipette must be ensured to be within the range provided by the pipette in order to meet the requirements of inaccuracy and inaccuracy
Analysis: The presence of air cushion is the main reason for the inaccuracy of the pipette. The selection of a pipette should be based on the principle of maximizing the range and minimizing the amount of liquid transferred close to the target.
Error: Absorbing liquids with strong volatility
Correct: It is not recommended to use a regular pipette for strong volatile liquid transfer
Analysis: If it is necessary to remove highly volatile liquids, the pipette should be opened immediately after the transfer is completed to allow the vapor to evaporate. At the same time, it is recommended to use an external piston pipette.
Error: The suction and discharge speeds are too fast
Correct: Slowly inhale and slowly release
Analysis: Quick suction can easily cause liquid to flush up for pipettes with a range of 1mL or more. Excessive liquid release will increase the residual amount of liquid.