A measuring device for accurately removing a certain volume of solution. A pipette is a measuring instrument, which is only used to measure the volume of the solution it releases. It is a slender glass tube with an enlarged part in the middle. Its lower end is in the shape of a sharp mouth, and its upper neck is engraved with a marking line, which is a sign of accurate volume.
Commonly used pipettes have specifications such as 5 10, 25, 50 and 75. Usually, a graduated straight glass tube is also called a pipette (see figure 1). Commonly used pipettes are 1, 2, 5, 10mL. Pipets and the volume that pipettes move can usually be accurate to 0.0 1mL.
According to the volume and requirements of the transfer solution, choose a pipette with appropriate specifications for use. In titration analysis, pipette is generally used to transfer the solution accurately, and when the reaction needs to control the amount of test solution, pipette is generally used.
Inspection instrument
pipette
Check the pipette nozzle and tip for damage. If it is damaged, it cannot be used.
Cleaning instrument
Rinse with tap water first, and then soak with chromic acid cleaning solution. The operation method is as follows: hold the pipette or the upper end of the pipette in a proper position with the right hand, with the index finger close to the upper mouth of the pipette, the middle finger and the ring finger open to hold the outside of the pipette, the thumb holds the inside of the pipette between the middle finger and the ring finger, and the little finger naturally relaxes; Hold the ear wash ball in your left hand, the ear suction ball in your palm, and the tip is facing down. Hold the ear-absorbing ball tightly and exhaust the air in the ball. Insert the tip of the ear-absorbing ball into or close to the upper mouth of the pipette, and be careful not to leak air. Slowly loosen the fingers of the left hand, slowly suck the washing liquid into the tube until the part above the scale line, take out the ear-absorbing ball, quickly block the upper mouth of the pipette (pipette) with the index finger of the right hand, wait a moment, and then put the washing liquid back into the original bottle. Rinse the inner and outer walls of the pipette (pipette) with tap water until no water drops hang, then rinse it with distilled water for three times, and control the water to dry for later use.
Inhalation solution
Shake the solution to be sucked evenly, pour a small part of the solution to be sucked into a clean and dry small beaker, suck up the water inside and outside the tip of the cleaned pipette with filter paper, and insert it into the small beaker to suck out the solution. When the capacity of the pipette reaches 65,438+0/3, immediately press the nozzle with the index finger of the right hand, take it out, hold the pipette horizontally and rotate it to make the solution flow all over the inner wall of the whole tube, and discharge the solution from the tip of the lower end into the waste liquid cup. In this way, the solution can be absorbed after wetting for 3-4 times.
Wet and wash the pipette with the liquid to be sucked, then insert it at the position 1 ~ 2 cm below the liquid surface to be sucked, and suck the liquid with the ear-sucking ball according to the above operation method (note that the pipette should not be inserted too deep into the solution, and it should be inserted downward when sucking the liquid, and always keep this depth). When the liquid level in the tube rises to about 1 ~ 2 cm above the scale line, quickly block the nozzle with the index finger of the right hand (at this time, if the solution falls below the standard line, it should be sucked again), lift the pipette out of the liquid level to be sucked, lift it after the tip of the tube touches the inner wall of the container to be sucked for a while, and suck up a small amount of solution adhered to the pipette or the lower end of the pipette with filter paper. (When moving the pipette or pipette, the pipette or pipette should be vertical and cannot be tilted. )
Regulating liquid level
pipette
Pick up another clean beaker from the left hand and put the pipette tip close to the inner wall of the beaker. Keep the beaker tilted to keep the pipette vertical, and keep the scale line and the line of sight horizontal (the left hand can't touch the pipette). Gently loosen the index finger (gently turn the pipette or pipette) to make the solution in the tube slowly flow out from the lower mouth. When the liquid level is close to the scale line, press the right index finger tightly, pause for a moment, then put the meniscus bottom line of the solution in the above way until it is tangent to the upper edge of the scale line, and immediately press the nozzle with the index finger. Move the tip close to the inner wall of the beaker, move it to the mouth of the beaker a little, and remove the droplets from the tip. Carefully move the pipette into the container containing the solution.
Release solution
Stand the pipette or pipette upright, tilt the receiver, let go of the index finger and let the solution flow down the inner wall of the receiver. After the solution in the tube flows out, keep the drainage state 15s, slide the tip of the pipette or pipette back and forth against the tube wall for several times (or rotate the pipette tip around the inner wall of the receiver), and take out the pipette (a small amount of solution remains on the inner wall of the tube end, which cannot be caused to flow out by strong external force). Except those marked with the word "blow" on the tube body, it can be blown out with ear washing balls, and it is not allowed to be kept).
Cleaning instrument
Use of pipette
Clean the pipette and put it on the pipette rack.
I hope it can help you solve the problem.