Workstation tips are actually pipette tips. The polypropylene material is selected, which can be sterilized by high temperature and high pressure, the inner wall is siliconized, and does not touch liquid to ensure the accuracy of specimen transfer. Let's take a look at the classification of workstation tips:
As a consumable used with pipettes, tips can generally be divided into: standard tips; filter tips; low adsorption tips; no heat source tips, etc. according to different applications.
1. Standard type: It is a widely used tip, which can be used for almost all pipetting operations, which is the most economical type of tip.
2. Filter type: It is a consumable designed to avoid cross-contamination, and is often used in experiments such as molecular biology, cytology, and virology.
3. Low adsorption type: For experiments with high sensitivity requirements, or precious samples or reagents that are easy to remain, the low adsorption type can be selected to improve the recovery rate. The surface of the low adsorption type has been hydrophobic treated, which can reduce the residual situation of low surface tension liquid in the tip.
The cycle process of the workstation tip includes six steps: tip installation - volume setting - pre-wash tip - suction - liquid release - tip removal. Each step has an operating specification that needs to be followed. Let's take a look at it in detail.
1. Installation: The correct installation method is called the rotary installation method. The specific method is to insert the top of the white sleeve into the tip (whether it is a bulk tip or a boxed tip), and while pressing down gently, Rotate the pipette in the handle 180 degrees counterclockwise. Remember not to use too much force, let alone chop the tip to install, because doing so will cause unnecessary damage to the pipette in your hand.
2. Capacity setting: The correct capacity setting is divided into two steps, one is rough adjustment, that is, the capacity value is quickly adjusted to be close to your expected value through the discharge button; the second is fine adjustment, when the capacity value is close to your own expected value After the value is set, the pipette should be placed horizontally in front of you, and the volume value should be slowly adjusted to the expected value through the adjustment wheel, so as to avoid the influence of visual errors. When setting the capacity, there is another point that needs special attention. When we adjust from a large value to a small value, it is just right; but when we adjust from a small value to a large value, we need to adjust more than a third of a turn before returning, because there is a certain gap in the counter, which needs to be filled.
3. Pre-washing the tip: After we install a new tip or increase the capacity value, the liquid that needs to be transferred should be sucked and discharged two or three times, so that a homogeneous liquid film can be formed on the inner wall of the tip. , to ensure the precision and accuracy of pipetting work, so that the entire pipetting process has reproducibility. Secondly, when absorbing organic solvents or highly volatile liquids, volatile gases will form negative pressure in the white sleeve chamber, resulting in liquid leakage. At this time, we need to pre-wash four to six times to let the air in the white sleeve chamber. When the gas is saturated, the negative pressure will disappear automatically.
4. Liquid aspiration: first press the pipette discharge button to the No. 1 stop point, and then immerse the tip vertically into the liquid surface. The depth of immersion is: P2, P10 less than or equal to 1 mm, P20, P100, P200 less than or equal to 2 mm, P1000 is less than or equal to 3 mm, P5ML, P10ML is less than or equal to 4 mm (if the immersion is too deep, the hydraulic pressure will have a certain impact on the accuracy of the suction. Of course, the specific immersion depth should also be based on the liquid The size of the container can be controlled flexibly), release the button smoothly, and remember not to be too fast.
5. Discharging: When discharging, the suction head is close to the wall of the container. First press the discharge button to the No. 1 stop. After a short pause, press it to the second stop. This can ensure that there is no residual liquid in the suction head. . If residual liquid remains after this operation, you should consider replacing the tip.
6. Remove the tip: The removed tip must not be mixed with the new tip to avoid cross-contamination.
