The work of the pipette is that the piston realizes the suction and discharge of liquid through the telescopic movement of the spring. Under the push of the piston, part of the air is removed, and the liquid is sucked under the action of atmospheric pressure, and then the air is pushed by the piston to discharge the liquid. Flexible, in the use of the pipette, it is necessary to cooperate with this feature of the spring, so that the speed and force of the pipetting can be well controlled. The ordinary micropipette uses a built-in gas piston, and the piston is designed to be used in pipetting. The inside of the pipette relies on pushing the air for suction and discharge, and the piston does not directly contact the liquid. Another type of pipette uses an external piston. The piston is designed inside the suction head and directly in contact with the liquid, which is suitable for relatively large viscosity. , or the operation of liquids that are prone to bubbles. Pipettes are widely used in biochemical experiments. They are mainly used for repeated rapid quantitative pipetting. They can be operated with only one hand, which is very convenient. The accuracy of pipetting is ±(0.5%~1.5%), and the precision of pipetting is smaller, ≤0.5%.
Notes on using the pipette:
(1) When sucking the liquid, the thumb must be released slowly and steadily, and it is not allowed to release suddenly, in order to prevent the solution from being sucked too fast and rushing into the liquid dispenser to corrode the plunger and cause air leakage.
(2) In order to obtain higher precision, the pipette tip needs to absorb the sample solution once in advance, and then formally pipette, because when the serum protein solution or organic solvent is absorbed, a layer of "liquid film" will remain on the inner wall of the pipette tip, resulting in drainage. The amount is too small to cause errors.
(3) Liquids with high concentration and viscosity will cause errors. In order to eliminate the compensation amount of the error, it can be determined by experiment. The compensation amount can be set by changing the reading of the reading window with the adjustment knob.
(4) The liquid dispenser can be calibrated by weighing and calculating the weight of the pure water taken with an analytical balance. 1mL of distilled water weighs 0.9982g at 20°C.
(5) It is very inadvisable to tighten the pipette by repeatedly hitting the tip. Long-term operation will loosen the internal parts and damage the pipette.
(6) When the pipette is not equipped with a tip, do not pipette.
(7) When setting the range, please note that the set range is within the range of the pipette and do not turn the button out of the range, otherwise the mechanical device will be stuck and the pipette will be damaged. to the desired range
(8) The pipette is strictly prohibited to absorb highly volatile and corrosive liquids (such as concentrated acid, concentrated alkali, organic matter, etc.).
(9) It is strictly forbidden to use a pipette to mix the liquid.
(10) Do not use a large-scale pipette to pipette a small volume of liquid, so as not to affect the accuracy. At the same time, if you need to pipette a larger amount of liquid outside the range, please use a pipette to operate.