Pipette use steps and incorrect use
1. Factors affecting the accuracy of pipettes
(1) Temperature: When the room temperature is low, the hand temperature is high, which makes the air expand, and the error often occurs when inhaling the cold solution.
(2) Airtightness: the joint between the tip and the pipette body, and the long-term wear between the cylinders inside the pipette, causing errors
(3) Suction speed: it is easy to cause bubbles in the tip, and it will pollute the pipette tip.
(4) Volatilization of reagent: When a reagent having a high volatility is absorbed, steam enters the tip of the pipette, and the internal pressure is increased. As a result, when the liquid is pressed out, the pressure becomes large and an error occurs. Solution: It can be improved by repeatedly pumping 4-5 times.
2. Specific use method
Replace the tip method: the most accurate.
(1) Adjust the knob to the desired scale position. knack: First, it can be slightly more than a few, then turn back to the scale. Be careful not to exceed the maximum scale to avoid human error.
(2) Insert tip: When aseptic operation, pay attention to the action is fast and correct, can not touch the tip by hand, the intensity of the action should be consistent, prohibiting waste action. For normal operation, use the thumb index finger to tighten, but the hand can’t touch the tip of the tip.
(3) Finger pressure to the first stage, tip contact reagent. White tip into the liquid surface 1mm, yellow tip2-3mm, blue tip2-4mm, to avoid the error caused by the impact of hydraulic pressure.
(4) Slowly aspirate the reagent, prohibit the speed too fast, and the liquid enters the tip of the pipette.
(5) After removing the tip, first gently lean against the inner wall of the container to allow the liquid on the outer wall of the tip to flow down.
(6) Stick the tip on the inner wall of the target container, gently press it to the first section, and press out the liquid.
(7) The tip of the tip slides slightly on the inner wall of the container, retaining a small amount of liquid at the tip, removing the target container, and removing the tip from the finger, taking care not to spill the reagent.
A tip dispensing method: not suitable for volatile, toxic reagents.
(1) With the above A-D, after removing the liquid level, slowly press the first stage and press firmly to the second stage to press the reagent out.
(2) With the above C, slowly suck out the liquid.
(3) In the target container liquid, press the reagent to the second stage, pay attention to the same pressure as A, and also pay attention to the reagents do not splash around.
(4) Slowly return to the first paragraph and repeat the above operation. The purpose of reaching the target container’s original liquid does not contaminate the tip.
Method for transferring a few ul of valuable reagents:
(1) With the above A-D, after removing the liquid level, lightly press the inner wall of the container a few times to allow the outer wall liquid to flow down. The white tip goes below the liquid level of 1mm, which is the most important.
(2) The tip of the tip is immersed under the liquid level of the target container and slowly pressed to the first stage.
(3) Loosen, return to the first stage, re-inhale the liquid, repeat 4-5 times, and wash the liquid inside the tip.
(4) Move the tip of the tip out of the liquid surface, gently lean against the inner wall, and press out the liquid to the second stage.