The pipette gun is a common tool used by every inspector. Many people ignore the correct use of the pipette gun and some detailed operations. The following is a detailed description of several aspects.

1. How to use the pipette gun 1> Install the pipette head: Aim the pipette gun vertically at the opening of the pipette head, secure the pipette gun and the muzzle together and rotate it once to check the air tightness. 12> Set the measuring range: In order to reduce the error, usually when selecting a liquid with a volume of 0.1 to 2 ml, adjust the pipette scale to 900, and then pipet twice. When pipetting a liquid with a volume greater than 2 ml, , choose to use a 0.5 to 5 ml pipette, and turn the knob on the top of the pipette to adjust to the appropriate volume. 3> Aspirate liquid: Use your thumb to press the knob of the pipette gun to the first position, then submerge the pipette head into the liquid. After absorbing the liquid, slowly release your thumb, and the liquid will be sucked out. After sucking out, tilt the pipette 45 degrees, and then transfer it to the side tube where the liquid is placed. 4> Discharge the liquid: Place the suction tip against the wall of the side tube. Be careful not to extend the suction tip into the liquid. Use your thumb to slowly press the knob to the second position and all the liquid will be discharged. If there is any residue, press it repeatedly. 5>Remove the pipette tip: Press the ejection button to remove the pipette tip.

2. Pipetting method Before pipetting, make sure that the pipette, pipette tip and liquid are at the same temperature. When aspirating liquid, keep the pipette upright and insert the pipette tip 2-3 mm below the liquid surface. Before suctioning, you can suck up the liquid several times to moisten the suction nozzle (especially when you want to suck up liquids that are viscous or have a density different from water). Two pipetting methods can be adopted at this time. 1>Advanced pipetting method. Use your thumb to press the button to the first stopping point, then slowly release the button to return to the original point. Then press the button to the first stop point to discharge the liquid, pause for a moment and continue to press the button to the second stop point to blow out the remaining liquid. Finally release the button. 2>Reverse pipetting method. This method is generally used to transfer highly viscous liquids, biologically active liquids, easily foaming liquids, or extremely small amounts of liquid. The principle is to first inhale more liquid than the set range, and there is no need to blow out the remaining liquid when transferring the liquid. First press the button to the second stopping point, then slowly release the button to the original point. Then press the button to the first stop point to discharge the liquid of the set range, continue to hold the button at the first stop point (do not press it down again), remove the pipe head with residual liquid, and discard it.

3. Precautions for using the pipette (1) When absorbing liquid, be sure to release your thumb slowly and steadily, and never release it suddenly to prevent the solution from being sucked in too fast and rushing into the pipette to corrode the plunger and cause leakage. gas. (2) In order to obtain higher accuracy, the tip needs to absorb the sample solution once before formally pipetting, because when absorbing serum protein solution or organic solvent, a "liquid film" will remain on the inner wall of the tip, causing liquid drainage. The amount is too small and causes errors. (3) Liquids with high concentration and viscosity will produce errors. The compensation amount to eliminate the error can be determined by experiments. The compensation amount can be set by changing the reading in the reading window with the adjustment knob. (4) The pipette gun can be calibrated by weighing the weight of the pure water taken with an analytical balance and calculating. 1mL of distilled water weighs 0.9982g at 20°C. (5) It is very undesirable to tighten the pipette by repeatedly hitting the tip. Long-term operation will loosen the internal parts and damage the pipette. (6) Do not pipette when the pipette is not equipped with a suction tip. (7) When setting the measuring range, please pay attention to rotating it to the required measuring range. The numbers are clearly in the display window. The set measuring range is within the range of the pipetting gun. Do not turn the button out of the measuring range, otherwise the mechanical device will be jammed and damaged. pipette gun. (8) The pipette is strictly prohibited from absorbing highly volatile and corrosive liquids (such as concentrated acid, concentrated alkali, organic matter, etc.). (9) It is strictly prohibited to use a pipette to mix the liquid. (10) Do not use a large-capacity pipette to transfer small volumes of liquid to avoid affecting accuracy. At the same time, if you need to transfer a larger amount of liquid outside the measuring range, please use a pipette. After use, please adjust the pipette scale to the maximum capacity scale and place it vertically on the pipette holder. Avoid turning the pipette filled with liquid upside down or laying it flat to prevent the liquid from flowing back and corroding the internal parts. Pipettes require regular calibration, which can be done in a laboratory or a third-party metrology department.